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[Federal Register: July 29, 2005 (Volume 70, Number 145)]
[Proposed Rules]               
[Page 43949-43989]


Part II

Department of Labor


Mine Safety and Health Administration


30 CFR Parts 56, 57, and 71

Asbestos Exposure Limit; Proposed Rule

[[Page 43950]]



Mine Safety and Health Administration

30 CFR Parts 56, 57, and 71

RIN: 1219-AB24

Asbestos Exposure Limit

AGENCY: Mine Safety and Health Administration (MSHA), Labor.

ACTION: Proposed rule; notice of public hearings.


SUMMARY: We (MSHA) are proposing to revise our existing health 
standards for asbestos exposure at metal and nonmetal mines, surface 
coal mines, and surface areas of underground coal mines. The proposed 
rule would reduce the full-shift permissible exposure limit and the 
excursion limit for airborne asbestos fibers, and make several 
nonsubstantive changes to add clarity to the standard. Exposure to 
asbestos has been associated with lung and other cancers, 
mesotheliomas, and asbestosis. This proposed rule would help assure 
that fewer miners who work in an environment where asbestos is present 
would suffer material impairment of health or functional capacity over 
their working lifetime.

DATES: We must receive your comments on or before September 20, 2005. 
We will hold public hearings on October 18 and 20. Details about the 
public hearings are in the SUPPLEMENTARY INFORMATION section of this 

ADDRESSES: (1) To submit comments, please include ``RIN: 1219-AB24'' in 
the subject line of the message and send them to us at either of the 
following addresses.
     Federal e-Rulemaking portal: Go to 
and follow the online instructions for submitting comments.
     E-mail: If you are unable to 
submit comments electronically, please identify them by ``RIN: 1219-
AB24'' and send them to us by any of the following methods.
     Fax: 202-693-9441.
     Mail, hand delivery, or courier: MSHA, Office of 
Standards, Regulations, and Variances, 1100 Wilson Blvd., Rm. 2350, 
Arlington, VA 22209-3939.
    (2) We will post all comments on the Internet without change, 
including any personal information they may contain. You may access the 
rulemaking docket via the Internet at 
or in person at MSHA's public reading room at 1100 Wilson Blvd., Rm. 
2349, Arlington, VA.
    (3) To receive an e-mail notification when we publish rulemaking 
documents in the Federal Register, subscribe to our list serve at

FOR FURTHER INFORMATION CONTACT: Rebecca J. Smith at 202-693-9440 
(Voice), 202-693-9441 (Fax), or (E-mail).


I. Introduction

A. Outline of Preamble

    We are including the following outline to help you find information 
in this preamble more quickly.

I. Introduction
    A. Outline of Preamble
    B. Dates and Locations for Public Hearings
    C. Executive Summary
    D. Abbreviations and Acronyms
II. Background
    A. Scope of Proposed Rule
    B. Where Asbestos Is Found at Mining Operations
    C. Asbestos Minerals
III. History of Asbestos Regulation
    A. MSHA's Asbestos Standards for Mining
    B. OSHA's Asbestos Standards for General Industry and 
    C. Other Federal Agencies Regulating Asbestos
    D. Other Asbestos-Related Activities
    E. U.S. Department of Labor, Office of the Inspector General 
IV. Health Effects of Asbestos Exposure
    A. Summary of Asbestos Health Hazards
    B. Factors Affecting the Occurrence and Severity of Disease
    C. Specific Human Health Effects
    D. Support from Toxicological Studies of Human Health Effects of 
Asbestos Exposure
V. Characterization and Assessment of Exposures in Mining
    A. Determining Asbestos Exposures in Mining
    B. Exposures from Naturally Occurring Asbestos
    C. Exposures from Introduced (Commercial) Asbestos
    D. Sampling Data and Exposure Calculations
VI. The Application of OSHA's Risk Assessment to Mining
    A. Summary of Studies Used by OSHA in Its Risk Assessment
    B. Models Selected by OSHA (1986) for Specified Endpoints and 
for the Determination of Its PEL and STEL
    C. OSHA's Selection of Its PEL (0.1 f/cc)
    D. Applicability of OSHA's Risk Assessment to the Mining 
    E. Significance of Risk
VII. Section-by-Section Discussion of Proposed Rule
    A. Sections 56/57.5001(b)(1) and 71.702(a): Definitions
    B. Sections 56/57.5001(b)(2) and 71.702(b): Permissible Exposure 
Limits (PELs)
    C. Sections 56/57.5001(b)(3) and 71.702(c): Measurement of 
Airborne Fiber Concentration
    D. Discussion of Asbestos Take-Home Contamination
    E. Section 71.701(c) and (d): Sampling; General Requirements
VIII. Regulatory Analyses
    A. Executive Order (E.O.) 12866
    B. Feasibility
    C. Alternatives Considered
    D. Regulatory Flexibility Analysis (RFA) and Small Business 
Regulatory Enforcement Fairness Act (SBREFA)
    E. Other Regulatory Considerations
IX. Copy of the OSHA Reference Method (ORM)
X. References Cited in the Preamble

B. Dates and Locations for Public Hearings

    We will hold two public hearings. If you wish to make a statement 
for the record, please submit your request to us at least 5 days prior 
to the hearing dates by one of the methods listed in the ADDRESSES 
section above. The hearings will begin at 9 a.m. with an opening 
statement from MSHA, followed by statements or presentations from the 
public, and end after the last speaker (in any event not later than 5 
p.m.) on the following dates at the locations indicated:

October 18, 2005, Denver Federal Center, Sixth and Kipling, Second 
Street, Building 25, Denver, Colorado 80225, Phone: 303-231-5412.
October 20, 2005, Mine Safety and Health Administration, 1100 Wilson 
Boulevard, Room 2539, Arlington, Virginia 22209, Phone: 202-693-9457.
    We will hear scheduled speakers first, in the order that they sign 
in; however, you do not have to make a written request to speak. To the 
extent time is available, we will hear from persons making same-day 
requests. The presiding official may exercise discretion to ensure the 
orderly progress of the hearing by limiting the time allocated to each 
speaker for their presentation.
    The hearings will be conducted in an informal manner. Although 
formal rules of evidence or cross examination will not apply, the 
hearing panel may ask questions of speakers and a verbatim transcript 
of the proceedings will be prepared and made a part of the rulemaking 
record. We also will post the transcript on MSHA's Home Page at
, on the Asbestos Single Source Page.

    Speakers and other attendees may present information to the MSHA 
panel for inclusion in the rulemaking record. We will accept written 
comments and data for the record from any interested party, including 
those not presenting oral statements. The post-hearing comment period 
will close on November 21, 2005, 30 days after the last public hearing.

[[Page 43951]]

C. Executive Summary

    In March of 2001, the U.S. Department of Labor, Office of the 
Inspector General (OIG) published a report evaluating MSHA's 
enforcement actions at the vermiculite mine in Libby, Montana. The 
widespread asbestos contamination at this mine and surrounding 
community, together with the prevalence of asbestos-related illnesses 
and fatalities among persons living in this community, attracted press 
and public attention, which prompted the OIG investigation and report. 
The OIG found that MSHA had conducted regular inspections and personal 
exposure sampling at the mine, as required by the Federal Mine Safety 
and Health Act of 1977 (Mine Act). The OIG report stated, ``We do not 
believe that more inspections or sampling would have prevented the 
current situation in Libby.'' The OIG made five recommendations to 
MSHA; two of which we implemented immediately. The remaining 
recommendations are listed below:
     Lower the existing permissible exposure limit (PEL) for 
asbestos to a more protective level.
     Use transmission electron microscopy (TEM) instead of 
phase contrast microscopy (PCM) in the initial analysis of fiber 
samples that may contain asbestos.
     Implement special safety requirements to address take-home 
    In response to the OIG's recommendations, MSHA published an advance 
notice of proposed rulemaking (ANPRM) on March 29, 2002 (67 FR 15134). 
MSHA also held seven public meetings around the country to seek input 
and obtain public comment on how best to protect miners from exposure 
to asbestos.
    Following review of all public comments and testimony taken at the 
public meetings, and relying on OSHA's 1986 asbestos risk assessment, 
we determined that it is appropriate to propose reducing the PELs for 
asbestos and clarify criteria for asbestos sample analysis. To enhance 
the health and safety of miners, we are proposing to lower the existing 
8-hour, time-weighted average (TWA) PEL of 2.0 f/cc to 0.1 f/cc, and to 
lower the short-term limit from 10.0 f/cc over a minimum sampling time 
of 15 minutes to an excursion limit PEL of 1.0 f/cc over a minimum 
sampling time of 30 minutes. To clarify the criteria for the analytical 
method in our existing standards, we are proposing to incorporate a 
reference to Appendix A of OSHA's asbestos standard (29 CFR 1910.1001). 
Appendix A specifies basic elements of a PCM method for analyzing 
airborne asbestos samples. It includes the same analytical elements 
specified in our existing standards and allows MSHA's use of other 
methods that meet the statistical equivalency criteria in OSHA's 
asbestos standard.
    The scope of this proposed rule, therefore, is limited to lowering 
the permissible exposure limits, an issue raised by the OIG; 
incorporating Appendix A of OSHA's asbestos standard for the analysis 
of our asbestos samples; and making several nonsubstantive conforming 
amendments to our existing rule language. After considering several 
regulatory approaches to prevent take-home contamination, we determined 
that non-regulatory measures could adequately address this potential 

D. Abbreviations and Acronyms

    As a quick reference, we list below some of the abbreviations used 
in the preamble.

29 CFR Title 29, Code of Federal Regulations
30 CFR Title 30, Code of Federal Regulations
AFL-CIO American Federation of Labor and Congress of Industrial 
ATSDR Agency for Toxic Substances and Disease Registry, Centers for 
Disease Control and Prevention, U.S. Department of Health and Human 
Bureau former Bureau of Mines, U.S. Department of the Interior
cc cubic centimeter (cm3) = milliliter (mL)
EPA U.S. Environmental Protection Agency
f fiber(s)
FR Federal Register
Lpm liter(s) per minute
MESA former Mining Enforcement and Safety Administration, U.S. 
Department of the Interior (predecessor to MSHA)
MSHA Mine Safety and Health Administration, U.S. Department of Labor
mm millimeter = 1 thousandth of a meter (0.001 m)
mL milliliter = 1 thousandth of a liter (0.001 L) = cubic centimeter
NIOSH National Institute for Occupational Safety and Health, Centers 
for Disease Control and Prevention, U.S. Department of Health and 
Human Services
OIG Office of the Inspector General, U.S. Department of Labor
OSHA Occupational Safety and Health Administration, U.S. Department 
of Labor
PCM phase contrast microscopy
PEL permissible exposure limit
PLM polarized light microscopy
STEL short-term exposure limit
SWA shift-weighted average concentration
TEM transmission electron microscopy
TWA time-weighted average concentration
[mu]m micron = micrometer = 1 millionth of a meter (0.000001 m)
USGS U.S. Geological Survey, U.S. Department of the Interior

II. Background

A. Scope of Proposed Rule

    This proposed rule would apply to metal and nonmetal mines, surface 
coal mines, and the surface areas of underground coal mines. Because 
asbestos from any source poses a health hazard to miners if they inhale 
it, the proposed rule would cover all miners exposed to asbestos 
whether naturally occurring or contained in building materials, in 
other manufactured products at the mine, or in mine waste or tailings.
    The National Institute for Occupational Safety and Health (NIOSH) 
and other research organizations and scientists (see Table VI-5) have 
observed the occurrence of cancers and asbestosis among metal and 
nonmetal miners involved in the mining and milling of commodities that 
contain asbestos. For this reason, our primary focus at metal and 
nonmetal mines is on asbestos in pockets or veins of mined commodities. 
Historically, there has been no evidence of coal miners encountering 
naturally occurring asbestos.\1\ The more likely exposure to asbestos 
in coal mining would occur from introduced asbestos-containing 
products, such as asbestos-containing building materials (ACBM) in 
surface structures.

    \1\ Personal communication with Professor Kot Unrug, Department 
of Mining Engineering, University of Kentucky, on November 14, 2003; 
and with Syd S. Peng, Chairman, Department of Mining Engineering, 
College of Engineering and Mineral Resources, West Virginia 
University, the week of October 24, 2003.

    In 2000, the OIG investigated MSHA's activities at the vermiculite 
mine in Libby, Montana. The OIG's conclusions and recommendations, 
discussed later, are consistent with MSHA's observations and concerns 
     Miners are exposed to asbestos at mining operations where 
the ore body or surrounding rock contains asbestos;
     Miners are potentially exposed to airborne asbestos at 
mine facilities with installed asbestos-containing material when it is 
disturbed during maintenance, construction, renovation, or demolition 
activities; and
     Family and community are potentially exposed if miners 
take asbestos home on their person, clothes, or equipment, or in their 
    We developed this proposed rule based on our experience with 
asbestos, our assessment of the health risks, the OIG's 
recommendations, and public comments on MSHA's ANPRM addressing the 
OIG's recommendations. We received numerous comments in response to the 
ANPRM and at the

[[Page 43952]]

public meetings, some of which suggested or supported additional 
requirements beyond those addressed by the OIG. We believe that the 
comments to the ANPRM do not justify an expansion of the scope, at this 
time, beyond the recommendations specifically raised in the OIG report.
    On the contrary, we believe that our data support a narrowed scope 
in that we specifically are not proposing two of the OIG's 
recommendations, i.e., routine use of TEM for the initial analysis of 
exposure samples and promulgation of standards to prevent take-home 
contamination. We are proposing, however, to lower our permissible 
exposure limits.
    We have decided not to propose to change our existing definition of 
asbestos in this rulemaking. There are several reasons for this.
    First, this rulemaking is limited in scope. We believe that a 20-
fold lowering of the exposure limits, as we have proposed, together 
with our enhanced measures to educate the mining community about the 
asbestos hazard in mining, would increase protection for miners and 
help avoid the future development of situations such as that in Libby, 
    Second, interest in the definition of asbestos extends to numerous 
agencies in Federal, state, and local governments. Our existing 
definition is consistent with several Federal agencies' regulatory 
provisions, including OSHA's. Changing the definition would require 
considerable interagency consultation and coordination; additional 
scientific evaluation; and an unnecessary delay in providing miners 
access to the benefits of this proposed rule.
    Third, we believe another Libby-like mining operation would not 
exist today because such a business arguably would not be economically 
viable. If a mine's ore contained significant amounts of asbestos-like 
minerals, there is a strong likelihood of potential liability risks, 
both from customers and workers, and the possibility that the mine's 
product would be commercially unmarketable. Such market forces are 
likely to compel mining companies of all sizes to sample the ore for 
the presence of hazardous fibrous minerals before purchasing or 
developing a mine site. In our view, these commercial reasons make it 
unlikely that a new Libby-like mining condition would arise in the 

B. Where Asbestos Is Found at Mining Operations

    Asbestos is no longer mined as a commodity in the United States. 
Even so, veins, pockets, or intrusions of asbestos have been found in 
other ores in specific geographic regions, primarily in metamorphic or 
igneous rock.\2\ Although less common, it is not impossible to find 
asbestos in sedimentary rock, soil, and air from the weathering or 
abrasion of other asbestos-bearing rock.\3\ The areas where asbestos 
may be located can be determined from an understanding of the 
mineralogy of asbestos and the geology required for its formation. In 
some cases, visual inspection can detect the presence of asbestos. MSHA 
experience indicates that miners may encounter asbestos during the 
mining of a number of mineral commodities,\4\ such as talc, limestone 
and dolomite, vermiculite, wollastonite, banded ironstone and taconite, 
lizardite, and antigorite. Not all mines of a specific commodity 
contain asbestos in the ore, however, and the mines that do have 
asbestos in the ore may encounter it rarely.

    \2\ MSHA (Bank), 1980.
    \3\ USGS, 1995.
    \4\ Roggli et al., 2002; Selden et al., 2001; Amandus et al., 
Part I, 1987; Amandus et al., Part III, 1987; Amandus and Wheeler, 
Part II, 1987.

    Asbestos also is contained in building materials and other 
manufactured products found at mines. Contrary to the common public 
perception, asbestos is not banned in the United States.\5\ The U.S. 
Geological Survey (USGS) estimates that about 13,000 metric tons (29 
million pounds) of asbestos were used in product manufacturing in the 
United States during 2001.\6\ In addition to domestic manufacturing, 
the United States continues to import products that contain asbestos. 
Asbestos may be used for a number of purposes at a mine including 
insulation; reinforcement of cements; reinforcement of floor, wall, and 
building tile; and automotive clutch and brake linings.\7\ If asbestos 
is present at the mine, miners in the vicinity are potentially at 
increased risk from asbestos exposure, regardless of whether or not 
they are actually working with asbestos.

    \5\ GETF Report, pp. 12-13, 2003.
    \6\ USGS (Virta), p. 28, 2003.
    \7\ Lemen, 2003; Paustenbach et al., 2003.

C. Asbestos Minerals

    To understand the scientific literature, information about 
asbestos, and the issues raised in the public comments, it is important 
to understand the terminology used to describe minerals, asbestos, and 
fibers. This section briefly reviews a number of key terms and concepts 
associated with asbestos that we use in discussing this proposed rule.
1. Mineralogical Classification and Mineral Names
    The terminology used to refer to how minerals form and how they are 
named is complex. A mineral's physical properties, composition, 
crystalline structure, and morphology determine its classification. 
Asbestos minerals belong to either the serpentine (sheet silicate) or 
the amphibole (double-chain silicate) family of minerals. Most of the 
difficulties in classifying minerals as asbestos have involved the 
amphiboles. The formation of a particular mineral (chemical 
composition) or habit (morphology, crystalline structure) occurs 
gradually and may be incomplete, producing intermediate minerals that 
are difficult to classify. In the past, there have been several 
different systems used to classify and name minerals that, in some 
instances, led to inconsistent terminology and classification. 
Currently, there is no single, universally accepted system for naming 
    Asbestos is a commercial term used to describe certain naturally 
occurring, hydrated silicate minerals. Several Federal agencies have 
regulations that focus on these minerals. The properties of asbestos 
that give it commercial value include low electrical and thermal 
conductivity, chemical and crystalline stability and durability, high 
tensile strength, flexibility, and friability. Much of the existing 
health risk data for asbestos uses commercial mineral terminology. 
Meeker et al. (2003) recognized the confusion associated with asbestos 
nomenclature, stating--

    Within much of the existing asbestos literature, mineral names 
are not applied in a uniform manner and are not all consistent with 
presently accepted mineralogical nomenclature and definitions.

    a. Variations in Mineral Morphology.
    There are many types of crystal habits, such as fibrous, acicular 
(slender and needle-like), massive (irregular form), and columnar 
(stout and column-like). The morphology of a mineral may not fit a 
precise definition. For example, Meeker et al. (2003) state that the 
Libby amphiboles contain ``a complete range of morphologies from 
prismatic crystals to asbestiform fibers.'' Some minerals crystallize 
in more than one habit. Some minerals, which can form in different 
habits, have a different name for each habit; others do not.\8\ For 
example, crocidolite is the name for the asbestiform habit and 
riebeckite is the name for the same mineral in its nonasbestiform 
habit. Tremolite and actinolite do not have different names

[[Page 43953]]

depending on habit; therefore, to distinguish between the different 
habits, the descriptive term ``asbestiform'' or ``asbestos'' is added 
to the mineral's name. If the identifying, descriptive term is not used 
with the mineral name, misunderstandings or mistakes may occur.

    \8\ Reger and Morgan, 1990; ATSDR, p. 138, 2001.

    b. Variations in Mineral Composition.
    Atoms similar in size and valence state can replace each other 
within a mineral's crystal lattice, resulting in the formation of a 
different mineral in the same mineral series. This process is gradual 
and can occur to a different extent in the same mineral depending on 
the geological conditions during its formation. For example, tremolite 
contains magnesium, but no (or little) iron, and holds an end member 
position in its mineral series. Iron atoms can replace the magnesium 
atoms in tremolite and the resulting mineral may then be called 
actinolite. The quantity of iron needed before the mineral is called 
actinolite varies depending on the mineral classification scheme used. 
Another example is winchite, which is an intermediate member of the 
tremolite-glaucophane series, as well as an end member in its own 
sodic-calcic series.\9\ Given the chemical similarity within the 
series, winchite 
22(OH)2] often has been reported as tremolite 

    \9\ Leake et al., p. 222, 1997.

    A specific rock formation may contain a continuum of minerals from 
one end member of a series to the other end member, creating a solid 
solution of intermediate minerals. These intermediate minerals are 
sometimes given names, while at other times they are not. Often, when 
the exact chemical composition is not determined or determined to be a 
number of different intermediate minerals, the mineral is named by one 
or more of its end members, such as tremolite-actinolite or 
cummingtonite-grunerite. The fibrous amphiboles in the Libby ore body, 
for example, contain both end members and several intermediate 
minerals. Meeker et al. (2003) state that--

    The variability of compositions on the micrometer scale can 
produce single fibrous particles that can have different amphibole 
names at different points of the particle.

    A mineral may also undergo transition to a different mineral 
series. Kelse and Thompson (1989), Ross (1978), and USGS (Virta, 2002) 
have commented on the chemical transition of anthophyllite to talc. 
Stewart and Lee (1992) stated that fibrous talc might contain 
intermediate particles not easily differentiated from asbestos. In the 
context of systems for naming and classifying fibrous amphiboles, 
Meeker et al. (2003) state that the regulatory literature often gives 
nominal compositions for a mineral without specifying chemical 
2. Differentiating Asbestiform and Nonasbestiform Habit
    In the asbestiform habit, mineral crystals grow forming long, 
thread-like fibers. When pressure is applied to an asbestos fiber, it 
bends much like a wire, rather than breaks. Fibers can separate into 
``fibrils'' of a smaller diameter (often less than 0.5 [mu]m). This 
effect is referred to as ``polyfilamentous,'' and should be viewed as 
one of the most important characteristics of asbestos. Appendix A of 
the Environmental Protection Agency's (EPA's) Method for the 
Determination of Asbestos in Bulk Building Materials \10\ defines 
asbestiform as follows:

    \10\ EPA, 1993.

    * * * a mineral that is like asbestos, i.e., crystallized with 
the habit [morphology] of asbestos. Some asbestiform minerals may 
lack the properties which make asbestos commercially valuable, such 
as long fiber length and high tensile strength. With the light 
microscope, the asbestiform habit is generally recognized by the 
following characteristics:
    Mean aspect [length to width] ratios ranging from 20:1 to 100:1 
or higher for fibers longer than 5 micrometers. Aspect ratios should 
be determined for fibers, not bundles.
    Very thin fibrils, usually less than 0.5 micrometers in width, 
and two or more of the following:

--Parallel fibers occurring in bundles,
--Fiber bundles displaying splayed ends,
--Matted masses of individual fibers, and/or
--Fibers showing curvature.

    In the nonasbestiform habit, mineral crystals do not grow in long 
thin fibers. They grow in a more massive habit. For example, a long 
thin crystal may not be polyfilamentous nor possess high tensile 
strength and flexibility, but may break rather than bend. When pressure 
is applied, the nonasbestiform crystals fracture easily into prismatic 
particles, which are called cleavage fragments because they result from 
the particle's breaking or cleavage, rather than the crystal's 
formation or growth. Some particles are acicular (needle shaped), and 
stair-step cleavage along the edges of some particles is common.
    Cleavage fragments may be formed when nonfibrous amphibole minerals 
are crushed, as may occur in mining and milling operations. Cleavage 
fragments are not asbestiform and do not fall within our definition of 
asbestos. For some minerals, distinguishing between asbestiform fibers 
and cleavage fragments in certain size ranges is difficult or 
impossible when only a small number of structures are available for 
review, as opposed to a representative population. Meeker et al. (2003) 
states that it is often difficult or impossible to determine 
differences between acicular cleavage fragments and asbestiform mineral 
fibers on an individual fiber basis. A determination as to whether a 
mineral is asbestiform or not must be made, where possible, by applying 
existing analytical methods. Although we have received comments 
regarding the hazards associated with cleavage fragments, we do not 
intend to modify our existing definition of asbestos with this 

III. History of Asbestos Regulation

    When Federal agencies responsible for occupational safety and 
health began to regulate occupational exposure to asbestos, studies had 
already established that the inhalation of asbestos fibers was a major 
cause of disability and death among exposed workers. The intent of 
these first asbestos rules was to protect workers from developing 

    \11\ GETF Report, p. 33, 2003.

A. MSHA's Asbestos Standards for Mining

    1967-1969. In 1967, under the former Bureau of Mines, predecessor 
to the Mining Enforcement and Safety Administration (MESA) and then 
MSHA, the standard for asbestos exposure in mining was an 8-hour, time-
weighted average (TWA) PEL of 5 mppcf (million particles per cubic foot 
of air). In 1969, the Bureau promulgated a 2 mppcf and 12 f/mL (fibers 
per milliliter) standard.
    1974-1976. In 1974, MESA promulgated a 5 f/mL standard for asbestos 
exposure in metal and nonmetal mines (39 FR 24316). In 1976, MESA 
promulgated a 2 f/cc standard (41 FR 10223) for asbestos exposure in 
surface areas of coal mines. We retained these standards under the 
authority of the Federal Mine Safety and Health Act of 1977.
    1978. In November 1978, we promulgated a 2 f/mL standard for 
asbestos exposure in metal and nonmetal mines (43 FR 54064). Since 
then, we have made only nonsubstantive changes to our asbestos 
standards, e.g., renumbering the section of the standard in 30 CFR.
    MSHA's existing standards for asbestos at metal and nonmetal mines 
at 30 CFR 56/57.5001 state,

[[Page 43954]]

    (b) The 8-hour time-weighted average airborne concentration of 
asbestos dust to which employees are exposed shall not exceed 2 
fibers per milliliter greater than 5 microns in length, as 
determined by the membrane filter method at 400-450 magnification (4 
millimeter objective) phase contrast illumination. No employees 
shall be exposed at any time to airborne concentrations of asbestos 
fibers in excess of 10 fibers longer than 5 micrometers, per 
milliliter of air, as determined by the membrane filter method over 
a minimum sampling time of 15 minutes. ``Asbestos'' is a generic 
term for a number of hydrated silicates that, when crushed or 
processed, separate into flexible fibers made up of fibrils. 
Although there are many asbestos minerals, the term ``asbestos'' as 
used herein is limited to the following minerals: chrysotile, 
Amosite, crocidolite, anthophylite asbestos, tremolite asbestos, and 
actinolite asbestos.

    The existing standard for asbestos at surface coal mines and 
surface work areas of underground coal mines at 30 CFR 71.702 states,

    (a) The 8-hour average airborne concentration of asbestos dust 
to which miners are exposed shall not exceed two fibers per cubic 
centimeter of air. Exposure to a concentration greater than two 
fibers per cubic centimeter of air, but not to exceed 10 fibers per 
cubic centimeter of air, may be permitted for a total of 1 hour each 
8-hour day. As used in this subpart, the term asbestos means 
chrysotile, amosite, crocidolite, anthophylite asbestos, tremolite 
asbestos, and actinolite asbestos but does not include nonfibrous or 
nonasbestiform minerals.
    (b) The determination of fiber concentration shall be made by 
counting all fibers longer than 5 micrometers in length and with a 
length-to-width ratio of at least 3 to 1 in at least 20 randomly 
selected fields using phase contrast microscopy at 400-450 

    1989. In 1989, as part of our Air Quality rulemaking, we proposed 
to lower the full-shift exposure limit for asbestos from 2 f/cc to 0.2 
f/cc to address the excessive risk quantified in the Occupational 
Safety and Health Administration's (OSHA's) 1986 asbestos rule (54 FR 
35760). The Air Quality rulemaking, however, was withdrawn on September 
26, 2002 (67 FR 60611). MSHA has not reinstated the Air Quality 
rulemaking at this time.

B. OSHA's Asbestos Standards for General Industry and Construction

    1971-1972. The initial promulgation of OSHA standards on May 29, 
1971 (36 FR 10466) included a 12 f/cc PEL for asbestos. Then, on 
December 7, 1971, in response to a petition by the Industrial Union 
Department of the AFL-CIO, OSHA issued an emergency temporary standard 
(ETS) on asbestos that established an 8-hour, TWA PEL of 5 f/cc and a 
peak exposure level (ceiling limit) of 10 f/cc. In June 1972, OSHA 
promulgated these limits in a final rule.
    1975. In October 1975, OSHA proposed to revise its asbestos 
standard by reducing the 8-hour, TWA PEL to 0.5 f/cc with a ceiling 
limit of 5 f/cc for 15 minutes (40 FR 47652). OSHA stated that 
sufficient medical and scientific evidence had accumulated to warrant 
the designation of asbestos as a human carcinogen and that advances in 
monitoring and protective technology made re-examination of the 
standard appropriate. The final rule, however, reduced OSHA's 8-hour, 
TWA asbestos PEL to 2 f/cc due to feasibility concerns. This limit 
remained in effect until OSHA revised it in 1986.
    1983-1986. On November 4, 1983, OSHA published another emergency 
temporary standard (ETS) for asbestos (48 FR 51086), which would have 
lowered the 8-hour, TWA PEL from 2 f/cc to 0.5 f/cc. The Asbestos 
Information Association challenged the ETS in the U.S. Court of Appeals 
for the 5th Circuit. On March 7, 1984, ruling on Asbestos Information 
Association/North America v. OSHA (727 F.2d 415, 1984), the Court 
invalidated the ETS. Subsequent to this decision, OSHA published a 
proposed rule (49 FR 14116) that, together with the ETS, proposed two 
alternatives for lowering the 8-hour, TWA PEL: 0.2 f/cc and 0.5 f/cc.
    On June 17, 1986, OSHA issued comprehensive asbestos standards (51 
FR 22612) governing occupational exposure to asbestos in general 
industry workplaces (29 CFR 1910.1001), construction workplaces (29 CFR 
1926.1101), and shipyards (29 CFR 1915.1001). The separate standards 
shared the same asbestos PEL and most ancillary requirements. These 
standards reduced OSHA's 8-hour, TWA PEL to 0.2 f/cc from the previous 
2 f/cc limit. OSHA added specific provisions in the construction 
standard to cover unique hazards relating to asbestos abatement and 
demolition jobs.
    Although tremolite, actinolite, and anthophyllite exist in 
different forms, OSHA determined that all forms of these minerals would 
continue to be regulated. Following promulgation of the rule, several 
parties requested an administrative stay of the standard claiming that 
OSHA improperly included nonasbestiform minerals. A temporary stay was 
granted and OSHA initiated rulemaking to remove the nonasbestiform 
types of these minerals from the scope of the asbestos standards.
    1988. Several major participants in OSHA's rulemaking challenged 
various provisions of the 1986 revised standards. In Building 
Construction Trades Division (BCTD), AFL-CIO v. Brock (838 F.2d 1258, 
1988), the U.S. Court of Appeals for the District of Columbia upheld 
most of the challenged provisions, but remanded certain issues to OSHA 
for reconsideration. In partial response, on September 14, 1988, OSHA 
promulgated an excursion limit of 1 f/cc for asbestos as measured over 
a 30-minute sampling period (53 FR 35610).
    1992. OSHA's 1986 standards had applied to occupational exposure to 
nonasbestiform actinolite, tremolite, and anthophylite. On June 8, 
1992, OSHA deleted the nonasbestiform types of these minerals from the 
scope of its asbestos standards. In evaluating the record, OSHA found 
(57 FR 24310-24311) insufficient evidence that nonasbestiform 
actinolite, tremolite, and anthophyllite present ``a risk similar in 
kind and extent'' to their asbestiform counterparts. Additionally, the 
evidence did not show that OSHA's removal of the nonasbestiform types 
of these three minerals from its asbestos standard ``will pose a 
significant risk to exposed employees.''
    1994. On August 10, 1994, OSHA published a final rule (59 FR 40964) 
that lowered its 8-hour, TWA PEL for asbestos to 0.1 f/cc and retained 
the 1 f/cc excursion limit as measured over 30 minutes.

C. Other Federal Agencies Regulating Asbestos

    Because the health hazards of exposure to asbestos are well 
recognized, it is highly regulated. OSHA and MSHA have the primary 
authority to regulate occupational exposures to asbestos. EPA regulates 
asbestos exposure of state and local government workers in those states 
that do not have an OSHA State Plan covering them. A number of other 
Federal agencies, primarily EPA and the Consumer Product Safety 
Commission (CPSC), regulate non-occupational asbestos exposures. For 
example, CPSC regulates asbestos in consumer products, such as patching 
compounds, under the Federal Hazardous Substances Act.
    EPA regulates asbestos in air and materials. EPA's activities have 
focused on environmental issues and the public health by reducing 
emissions of hazardous gases and dusts from large industrial sources, 
such as taconite ore processing,\12\ and the cleanup of contaminated 
waste sites. EPA also regulates asbestos in schools. The mining and 
processing of vermiculite in Libby, Montana, resulted in the spread

[[Page 43955]]

of asbestos to numerous homes, schools, and businesses throughout the 
town. In November 1999, EPA responded to a request to study the 
environmental contamination in the town of Libby and widespread 
illnesses and death among its residents. In October 2002, EPA 
designated the area as a Superfund site.

    \12\ EPA (68 FR 61868), 2003.

D. Other Asbestos-Related Activities

    There have been increasing numbers of studies on asbestos and its 
hazards over the past 40 years. These efforts encompass government, 
industry, and academia on a local, national, and international scale. 
Government agencies and scientific groups in the United States, such as 
the National Institute for Occupational Safety and Health (NIOSH), the 
Agency for Toxic Substances and Disease Registry (ATSDR), the American 
Conference of Governmental Industrial Hygienists (ACGIH), and the 
National Toxicology Program (NTP), have addressed issues involving 
carcinogens, such as asbestos. Organizations from other countries, such 
as the United Kingdom (Health and Safety Executive) and Germany 
(Deutche Forschungsgemeinschaft), also have addressed occupational 
exposure to asbestos and other carcinogens. Similarly, the 
International Agency for Research on Cancer (IARC) has published a 
monograph on asbestos that summarizes evidence of its 

    \13\ IARC, 1987.

1. Interagency Asbestos Work Group (IAWG)
    OSHA's and EPA's overlapping responsibilities and common interest 
in addressing asbestos hazards led to the formation of the IAWG. 
Participating Federal agencies include EPA, OSHA, CPSC, MSHA, NIOSH, 
ATSDR, USGS, and the National Institute of Standards and Technology 
(NIST). This work group of government agencies facilitates the sharing 
of information and coordination of activities, including regulatory 
activities, environmental assessment, technical assistance, consumer 
protection, and developments in environmental analysis of contaminants. 
The IAWG also seeks to harmonize the policies, procedures, and 
enforcement activities of the participating agencies, thus minimizing 
or eliminating potential conflicts for the regulated community. For 
example, the IAWG is currently discussing the Federal definition of 
2. National Institute for Occupational Safety and Health (NIOSH)
    The Workers' Family Protection Act of 1992 (29 U.S.C. 671A) 
directed NIOSH to study contamination of workers' homes by hazardous 
substances, including asbestos, transported from the workplace. ATSDR, 
EPA, OSHA, MSHA, the U.S. Department of Energy (DOE), and the Centers 
for Disease Control and Prevention (CDC) assisted NIOSH in conducting 
the study. For this proposed rule we focused on the asbestos-related 
results of these studies.
    NIOSH (1995) published its study results in a Report to Congress on 
Workers' Home Contamination Study Conducted under the Workers' Family 
Protection Act. This report summarizes incidents of home contamination, 
including the health consequences, sources, and levels of 
contamination. The study documents cases of asbestos reaching workers' 
homes in 36 states in the United States and in 28 other countries. 
These cases covered a wide variety of materials, industries, and 
occupations. The means by which hazardous substances reached workers' 
homes and families included taking the substance home on the worker's 
body, clothing, tools, and equipment; cottage industries (i.e., work 
performed on home property); and family visits to the workplace. In an 
effort to reach employers and workers, NIOSH (1997) published its 
recommendations in Protect Your Family: Reduce Contamination at Home. 
This pamphlet summarizes the NIOSH study and provides recommendations 
to prevent this contamination.
3. Agency for Toxic Substances and Disease Registry (ATSDR)
    The Superfund Amendments and Reauthorization Act of 1986 (SARA) 
directed ATSDR to prepare toxicological profiles for hazardous 
substances most commonly found at specific waste sites. ATSDR and EPA 
determined which hazardous substances pose the most significant 
potential threat to human health and targeted them for study. Asbestos 
is one of these targeted substances. ATSDR published one of the most 
current toxicological profiles for asbestos in September 2001, which 
was an update of an earlier asbestos profile.
    In October 2002, ATSDR sponsored a meeting of expert panelists who 
presented their evaluation of state-of-the-art research concerning the 
relationship between fiber length and the toxicity of asbestos and 
synthetic vitreous fibers. We have reviewed the evidence and arguments 
presented in the updated asbestos toxicological profile and the meeting 
proceedings and have discussed this information in this preamble, where 

E. U.S. Department of Labor, Office of the Inspector General (OIG)

    In November 1999, a Seattle newspaper published a series of 
articles on the unusually high incidence of asbestos-related illnesses 
and fatalities among individuals who had lived in Libby, Montana. There 
was extensive national media attention surrounding the widespread 
environmental contamination and asbestos-related deaths in Libby. Dust 
and construction materials from the nearby vermiculite mine were the 
alleged cause. This mine had produced about 90 percent of the world's 
supply of vermiculite from 1924 until 1992.
    Because MSHA had jurisdiction over the mine for two decades before 
it closed, the OIG investigated MSHA's enforcement actions at the mine. 
The OIG confirmed that the processing of vermiculite at the mine 
exposed miners to asbestos. The miners then, inadvertently, had carried 
the asbestos home on their clothes and in their personal vehicles.\14\ 
In doing this, the miners continued to expose themselves and family 

    \14\ Weis et al., 2001.

1. OIG Report on MSHA's Handling of Inspections at the W.R. Grace & 
Company Mine in Libby, Montana
    The OIG published its findings and recommendations in a report 
dated March 22, 2001. The OIG found that MSHA had appropriately 
conducted regular inspections and personal exposure sampling at the 
Libby mine and that there were no samples exceeding the 2.0 f/cc PEL 
for the 10 years prior to the mine closing in 1992. The OIG concluded, 
``We do not believe that more inspections or sampling would have 
prevented the current situation in Libby.'' The OIG stated its belief 
that there is a need for MSHA to lower its asbestos PEL.
    In its report, the OIG supported the development and implementation 
of control measures for asbestos and vermiculite mining and milling. 
They also made recommendations for improving our effectiveness in 
controlling this hazard. This proposed rule addresses our responses to 
several of the OIG's recommendations.
2. MSHA's Libby, Montana Experience
    W.R. Grace acquired the vermiculite mine in Libby, Montana, in 
1963. At that time, the amphibole in the

[[Page 43956]]

vermiculite was called tremolite, soda tremolite, soda-rich tremolite, 
or richterite, and researchers had already linked the mine dust to 
respiratory disease.\15\ The suggested exposure limit for asbestos in 
mining was much higher than current limits. The federal standard for 
asbestos in mining dropped from 5 mppcf (about 30 f/mL) in 1967 to 2 f/
mL in 1978. When MESA (predecessor agency to MSHA) began inspecting the 
operation, the exposure limit for asbestos was 5 f/mL.

    \15\ McDonald et al., 1986; Meeker et al., 2003; Peipins et al., 

    The mine operator, Federal mine inspectors, and representatives of 
the U.S. Public Health Service [part of the Centers for Disease Control 
and Prevention (CDC)] routinely sampled for asbestos at the Libby mine, 
starting before the mine switched to wet processing in 1974, and 
continued sampling periodically until the mine closed in 1992. MSHA 
sampling at the Libby mine found no exposures exceeding the 5.0 f/cc 
asbestos PEL from 1975 through 1978, and only a few over the 2.0 f/cc 
asbestos PEL from 1979 through 1986. Almost all the samples would have 
exceeded the 0.1 f/cc proposed limit. Miners' exposures continued to 
decrease and more recent sampling since 1986 found few exposures 
exceeding the OSHA PEL of 0.1 f/cc.
    The results from our personal exposure sampling at the Libby mine 
included many of the fibrous amphiboles present. In addition, the 
results from TEM analysis of the air samples characterized the 
mineralogy of the airborne fibers as tremolite and did not distinguish 
between the species of amphiboles. Further characterization of the 
amphibole minerals using Scanning Electron Microscopy/Energy Dispersive 
X-ray Spectroscopy technology shows proportions of about 84 percent 
winchite, 11 percent richterite, and 6 percent tremolite.\16\

    \16\ Meeker et al., 2003

    As early as 1980, MSHA had requested that NIOSH investigate health 
problems at all vermiculite operations, including the mine and mill in 
Libby, Montana. NIOSH published its study results in a series of three 
papers (Amandus et al., Part I, 1987; Amandus and Wheeler, Part II, 
1987; Amandus et al., Part III, 1987). The study of Amandus et al. 
(Part I, 1987) along with that of McDonald et al. (1986) found that, 
historically, the highest exposures to fibers at the Libby operation 
had occurred in the mill and that exposures had decreased between the 
1960's and 1970's. McDonald et al. (1986) reported--

    In 1974, the old dry and wet mills were closed and the ore was 
processed in a new mill built nearby which operated on an entirely 
wet basis in which separation was made by vibrating screens, 
Humphrey separators, and flotation.

McDonald et al. (1986) and Amandus and Wheeler (Part II, 1987) also 
showed that, even at reduced exposure levels, there was still increased 
risk of lung cancer among the Libby miners and millers.
3. MSHA's Efforts To Minimize Asbestos Take-Home Contamination
    ``Take-home'' contamination is contamination of workers' homes or 
vehicles by hazardous substances transported from the workplace. As 
discussed previously in this preamble, the widespread asbestos-related 
disease among the residents of Libby, Montana, was attributed, in part, 
to take-home contamination from the vermiculite mining and milling 
operation in that town. The OIG report on MSHA's activities recommended 
that we promulgate special safety standards similar to those in our 
1989 proposed Air Quality rule (54 FR 35760) to address take-home 
    In our 1989 Air Quality proposed rule, we had proposed that miners 
wear protective clothing and other personal protective equipment before 
entering areas containing asbestos. Our Air Quality proposed rule also 
would have required miners to remove their protective clothing and 
store them in adequate containers to be disposed of or decontaminated 
by the mine operator. These proposed requirements were similar to those 
in OSHA's asbestos standard and to NIOSH's recommendations.
    In March 2000, shortly after the series of articles on asbestos-
related illnesses and deaths in Libby, Montana, we issued a Program 
Information Bulletin (PIB No. P00-3) about asbestos. The PIB served to 
remind the mining industry of the potential health hazards from 
exposure to airborne asbestos fibers and to raise awareness about 
potential asbestos exposure for miners, their families, and their 
communities. At that time, we also issued a Health Hazard Information 
Card (No. 21) about asbestos for distribution to miners to raise their 
awareness about the health hazards related to asbestos exposure.
    The PIB included information about asbestos, its carcinogenic and 
other significant health effects, how miners could be exposed, where 
asbestos occurs naturally on mining property, and what types of 
commercial products may contain asbestos. It included recommendations 
to help mine operators reduce miners' exposures, to prevent or minimize 
take-home contamination, and for the selection and use of respiratory 
protection. The PIB also urged mine operators to minimize exposures, to 
improve controls, and to train miners, listing specific training topics 
as essential for miners potentially exposed to asbestos.
    During this same period, 2000 to 2003, we conducted an asbestos 
awareness campaign and increased asbestos sampling. Section VII.D of 
this preamble contains an additional discussion of measures to prevent 
asbestos ``take-home'' contamination.
    We have decided not to pursue a regulatory approach to minimizing 
asbestos ``take-home'' contamination. Based on the existing levels of 
asbestos exposures in the mining industry, comments on our 2002 ANPRM, 
and testimony at the subsequent public meetings, we have determined 
that a non-regulatory approach would be effective in minimizing 
asbestos take-home contamination from mining operations.
4. Training Inspectors to Recognize and Sample for Asbestos
    The OIG recommended that we increase MSHA inspectors' skills for 
providing asbestos compliance assistance to mine operators. In 
response, we developed a half-day multimedia training program that 
includes the following:
     A PowerPoint-based training presentation that examines 
MSHA's procedures for air and bulk asbestos sampling.
     An updated ``Chapter 8--Asbestos Fibers'' from the Metal 
and Nonmetal Health Inspection and Procedures Handbook that serves as a 
text for the training sessions.
     A ``hands-on'' segment that allows the inspectors to 
examine asbestos and asbestiform rock samples and the equipment used 
for bulk sampling, and that provides the inspectors instruction and 
practice in assembling and calibrating asbestos fiber air sampling 
    We gave this asbestos training to journeymen inspectors from March 
2002 through April 2003, and added it to the training program for 
entry-level inspectors.

IV. Health Effects of Asbestos Exposure

    The health hazards from exposure to asbestos were discussed 
extensively in the preamble to OSHA's 1983 final rule (51 FR 22615). 
Subsequently, researchers have confirmed and

[[Page 43957]]

increased our knowledge of these hazards. Exposures in occupational and 
environmental settings are generally due to inhalation, although some 
asbestos may be absorbed through ingestion. While the part of the body 
most likely affected (target organ) is the lung, adverse health effects 
may extend to the linings of the chest, abdominal, and pelvic cavities, 
and the gastrointestinal tract. The damage following chronic exposure 
to asbestos is cumulative and irreversible. Workplace exposures to 
asbestos may be chronic, continuing for many years. The symptoms of 
asbestos-related adverse health effects may not become evident for 20 
or more years after first exposure (latency period).

A. Summary of Asbestos Health Hazards

    This section presents an overview of human health effects from 
exposure to asbestos. We are proposing to use OSHA's 1986 risk 
assessment to estimate the risk from asbestos exposures in mining. 
OSHA's risk assessment has withstood legal scrutiny and the more recent 
studies discussed later in this preamble support it. MSHA has placed 
OSHA's risk assessment in the asbestos rulemaking record. It can also 
be found at

    Studies first identified health problems associated with 
occupational exposure to asbestos in the early 20th century among 
workers involved in the manufacturing or use of asbestos-containing 
products.\17\ Early studies identified the inhalation of asbestos as 
the cause of asbestosis, a slowly progressive disease that produces 
lung scarring and loss of lung elasticity. Studies also found that 
asbestos caused lung and several other types of cancer. For example, 
mesotheliomas, rare cancers of the lining of the chest or abdominal 
cavities, are almost exclusively attributable to asbestos exposure. 
Once diagnosed, they are rapidly fatal. Asbestos-related diseases have 
long latency periods, commonly not producing symptoms for 20 to 30 
years following initial exposure.

    \17\ GETF Report, p. 38, 2003; OSHA (40 FR 47654), 1975.

    In the late 1960's, scientists correlated phase contrast microscopy 
fiber counting methods with the earlier types of dust measurements. 
This procedure provided a means to estimate earlier workers' asbestos 
exposures and enabled researchers to develop a dose-response 
relationship with the occurrence of disease. The British Occupational 
Hygiene Society reported \18\ that a worker exposed to 100 fiber-years 
per cubic centimeter (e.g., 50 years at 2 f/cc, 25 years at 4 f/cc, 10 
years at 10 f/cc) would have a 1 percent risk of developing early signs 
of asbestosis. The correlation of exposure levels with the disease 
experience of populations of exposed workers provided a basis for 
setting an occupational exposure limit for asbestos measured by the 
concentration of the fibers in air.

    \18\ Lane et al., 1968; OSHA (40 FR 47654), 1975.

    As mentioned previously, the hazardous effects from exposure to 
asbestos are now well known. For this reason, our discussion in this 
section will focus on the results of the more recent studies and 
literature reviews, those published since the publication of OSHA's 
risk assessment, and those involving miners. One such review by 
Tweedale (2002) stated,

    Asbestos has become the leading cause of occupational related 
cancer death, and the second most fatal manufactured carcinogen 
(after tobacco). In the public's mind, asbestos has been a hazard 
since the 1960s and 1970s. However, the knowledge that the material 
was a mortal health hazard dates back at least a century, and its 
carcinogenic properties have been appreciated for more than 50 

    Greenberg (2003) also published a recent review of the biological 
effects of asbestos and provided a historical perspective similar to 
that of Tweedale.
    The three most commonly described adverse health effects associated 
with asbestos exposure are lung cancer, mesotheliomas, and pulmonary 
fibrosis (i.e., asbestosis). OSHA, in its 1986 asbestos rule, reviewed 
each of these diseases and provided details on the studies 
demonstrating the relationship between asbestos exposure and the 
clinical evidence of disease. In 2001, the ATSDR published an updated 
Toxicological Profile for Asbestos that also included an extensive 
discussion of these three diseases. A search of peer-reviewed 
scientific literature using databases, such as Gateway, PubMed, and 
ToxLine, accessed through the National Library of Medicine (NLM), 
yielded nearly 900 new references on asbestos from January 2000 to 
October 2003. Many of these recent articles \19\ continue to 
demonstrate and support findings of asbestos-induced lung cancer, 
mesotheliomas, and asbestosis, consistent with the conclusions of OSHA 
and ATSDR. Thus, in the scientific community, there is compelling 
evidence of the adverse health effects of asbestos exposure. This has 
led some researchers and stakeholders to recommend a worldwide ban of 

    \19\ Baron, 2001; Bolton et al., 2002; Manning et al., 2002; 
Nicholson, 2001; Osinubi et al., 2000; Roach et al., 2002.
    \20\ Maltoni, 1999.

B. Factors Affecting the Occurrence and Severity of Disease

    The toxicity of asbestos, and the subsequent occurrence of disease, 
is related to its concentration (C) in the mine air and to the duration 
(T) of the miner's exposure. Other variables, such as the fiber's 
characteristics or the effectiveness of the miner's lung clearance 
mechanisms, also affect disease severity.
1. Concentration (C)
    Currently, the concentration (C) of asbestos is expressed as the 
number of fibers per cubic centimeter (f/cc). Some studies have also 
reported asbestos concentrations in the number of fibers per milliliter 
(f/mL), which is an equivalent concentration to f/cc. MSHA's existing 
PELs for asbestos are expressed in f/mL for metal and nonmetal mines 
and as f/cc for coal mines. To improve consistency and avoid confusion, 
we express the concentration of airborne fibers as f/cc in this 
proposed rule, for both coal and metal and nonmetal mines.
    Older scientific literature (i.e., 1960's and 1970's) reported 
exposure concentrations as million particles per cubic foot (mppcf) and 
applied a conversion factor to convert mppcf to f/cc. OSHA (51 FR 
22617) used a factor of 1.4 when performing these conversions. More 
recently, Hodgson and Darnton (2000) recommended the use of a factor of 
3. In our evaluation of the scientific literature, we did not 
critically evaluate the impact of these and other conversion factors. 
We note this difference here for completeness. Because we are relying 
on OSHA's risk assessment, we are using OSHA's conversion factor
2. Time (T)
    Epidemiological and toxicological studies generally report time (T) 
in years (yr). The product of exposure concentration and exposure 
duration (i.e., C x T) is referred to as ``fiber-years''.\21\ When 
developing exposure-response relationships for asbestos-induced health 
effects, researchers typically use ``fiber-years'' to indicate the 
level of workplace exposure. Finkelstein \22\ noted, however, that this 
product of exposure concentration times duration of exposure (C x T) 
assumes an equal weighting of each variable (C, T).

    \21\ ATSDR, 2001; Fischer et al., 2002; Liddell, 2001; Pohlabeln 
et al., 2002.
    \22\ Finkelstein, 1995; ATSDR, p. 42, 2001.


[[Page 43958]]

3. Fiber Characteristics
    Baron (2001) reviewed techniques for the measurement of fibers and 
stated, ``* * * fiber dose, fiber dimension, and fiber durability are 
the three primary factors in determining fiber [asbestos] toxicity * * 
*''. Manning et al. (2002) also noted the important roles of bio-
persistence (i.e., durability), physical properties, and chemical 
properties in defining the ``toxicity, pathogenicity, and 
carcinogenicity'' of asbestos. Roach et al. (2002) stated that--

    Physical properties, such as length, diameter, length-to-width 
(aspect ratio), and texture, and chemical properties are believed to 
be determinants of fiber distribution [in the body] and disease 

    Many other investigators \23\ also have concluded that the 
dimensions of asbestos fibers are biologically important.

    \23\ ATSDR, 2001; Osinubi et al., 2000; Peacock et al., 2000; 
Langer et al., 1979.

    OSHA and MSHA currently specify that analysts count those fibers 
that are over 5.0 micrometers ([mu]m) in length with a length to 
diameter aspect ratio of at least 3:1. Several recent publications \24\ 
support this aspect ratio, although larger aspect ratios such as 5:1 or 
20:1 have been proposed.\25\ There is some evidence that longer, 
thinner asbestos fibers (e.g., greater than 20 [mu]m long and less than 
1 [mu]m in diameter) are more potent carcinogens than shorter fibers. 
Suzuki and Yuen (2002), however, concluded that ``Short, thin asbestos 
fibers should be included in the list of fiber types contributing to 
the induction of human malignant mesotheliomas * * * ''. More recently, 
Dodson et al. (2003) concluded that all lengths of asbestos fibers 
induce pathological responses and that researchers should exercise 
caution when excluding a population of inhaled fibers based on their 

    \24\ ATSDR, 2001; Osinubi et al., 2000.
    \25\ Wylie et al., 1985.

    We have determined that researchers have found neither a reliable 
method for predicting the contribution of fiber length to the 
development of disease, nor evidence establishing the exact 
relationship between them. There is suggestive evidence that the 
dimensions of asbestos fibers may vary with different diseases. A 
continuum may exist in which shorter, wider fibers produce one disease, 
such as asbestosis, and longer, thinner fibers produce another, such as 
mesotheliomas.\26\ The scientific community continues to publish new 
data that will enable regulatory agencies, such as MSHA, to better 
understand the relationship between fiber dimensions, durability, 
inhaled dose, and other important factors that determine the health 
risks of exposure not only to asbestos, but also to other fibers.

    \26\ ATSDR, pp. 39-41, 2001; Mossman, pp. 47-50, 2003.

4. Differences in Fiber Potency
    The theory that the differences among fibers have an effect on 
their ability to produce adverse effects on human health has received a 
great deal of attention. Hodgson and Darnton (2000), Browne (2001), and 
Liddell (2001) discuss a fiber gradient hypothesis, which is now termed 
the amphibole hypothesis. This hypothesis proposes that the amphiboles 
(e.g., crocidolite, amosite) are more hazardous than the serpentine, 
chrysotile. ATSDR (p. 39, 2001) recently stated that--

    Available evidence indicates that all asbestos fiber types are 
fibrogenic, although there may be some differences in relative 
potency among fiber types.

    In its 1986 asbestos rule, OSHA (51 FR 22628) stated that--

    * * * epidemiological and animal evidence, taken together, fail 
to establish a definitive risk differential for the various types of 
asbestos fiber. Accordingly, OSHA has * * * recognized that all 
types of asbestos fiber have the same fibrogenic and carcinogenic 
potential * * *

    In its comments on MSHA's asbestos ANPRM, NIOSH stated that--

    (3) experimental animal carcinogenicity studies with various 
minerals have provided strong evidence that the carcinogenic 
potential depends on the ``particle'' length and diameter. The 
consistency in tumorigenic responses observed for various mineral 
particles of the same size provides reasonable evidence that neither 
composition nor origin of the particle is a critical factor in 
carcinogenic potential; * * *

    This issue remains unresolved. Although possible differences in 
fiber potency are beyond the scope of this proposed rule, we will 
continue to monitor results of research in this area.
5. Lung Clearance Mechanisms
    Inhaled asbestos may deposit throughout the respiratory tract, 
depending on the aerodynamic behavior of the fibers.\27\ As noted by 
Baron (2001), `` * * * fiber aerodynamic behavior indicates that small 
diameter fibers are likely to reach into and deposit in the airways of 
the lungs.'' Clearing the lungs of deposited asbestos occurs by several 
mechanisms. In the mid-airways (i.e., bronchial region), small hair-
like cells sweep the mucus containing asbestos toward the throat, at 
which time it is swallowed or expectorated. The swallowing of mucus 
through this clearance mechanism can result in inhaled asbestos 
reaching the gastrointestinal tract.

    \27\ ICRP, 1966.

    In the air sacs deep within the lungs (the alveolar region), 
pulmonary macrophages engulf foreign matter, including asbestos fibers. 
The macrophages attempt to remove these fibers by transporting them to 
the circulatory or lymphatic system. Some studies have shown that 
groups of macrophages try to engulf longer fibers.\28\ When asbestos 
fibers are not cleared, they may initiate inflammation of the cells 
lining the alveoli. This inflammation leads to more serious physical 
effects in the lungs. OSHA (1986), ATSDR (2001), and several recent 
papers \29\ discuss these mechanisms for the pulmonary clearance of 

    \28\ Warheit, p. 308, 1993.
    \29\ Baron, 2001; Osinubi et al., 2000.

C. Specific Human Health Effects

1. Lung Cancer
    Lung cancer is a chronic, irreversible, and often fatal disease of 
the lungs. Epidemiological studies confirm, and toxicological studies 
support, the carcinogenicity of asbestos. (See section IV.D. below.) 
The form of lung cancer seen most often in asbestos-exposed individuals 
is bronchial carcinoma. Some of the risk factors for lung cancer 
include airborne asbestos concentration, duration of exposure, fiber 
dimensions, the age of the individual at the time of first exposure, 
and the number of years since the first exposure.\30\ Another major 
risk factor is the smoking of tobacco products. Numerous studies have 
concluded that there are synergistic effects between asbestos and 
tobacco smoke in the development of lung cancer.\31\ This is especially 
relevant to miners as NIOSH (May 2003) estimates that 33 percent of 
miners currently smoke.

    \30\ Yano et al., 2001; ATSDR, 2001.
    \31\ Bolton et al., 2002; Manning et al., 2002; OSHA, 1986.

    The mechanism through which asbestos causes lung cancer is under 
study. Recent papers by Manning et al. (2002), Xu et al. (2002), and 
Osinubi et al. (2000) describe a scheme of cell signaling and 
inflammation with the release of reactive oxygen species and reactive 
nitrogen species.
    The latency period for asbestos-related lung cancer is generally 
20-30 years, although some cases have been reported within 10 years, 
and some up to 50 years, after initial asbestos exposure.\32\ Lung 
cancer caused by

[[Page 43959]]

asbestos can progress even in the absence of continued exposure. Thus, 
in all of its stages, lung cancer constitutes a material impairment of 
human health or functional capacity.

    \32\ Roach et al., 2002.

    In the preamble to its 1986 asbestos standard (51 FR 22615), OSHA 
stated, ``Of all the diseases caused by asbestos, lung cancer 
constitutes the greatest health risk for American asbestos workers.'' 
OSHA (51 FR 22615-22616) also stated, ``* * * Asbestos exposure acts 
synergistically with cigarette smoking to multiply the risk of 
developing lung cancer.'' MSHA believes that the essential points of 
this statement remain true today.
    Steenland et al. (2003) estimated that there were about 150,000 
lung cancer deaths in 1997 in the United States, and that 6.3 to 13 
percent (i.e., 9,700 to 19,900) of these lung cancer deaths were 
occupationally-related. Steenland et al. (1996) also had estimated 
that, in the mid-1990's, there were about 5,400 asbestos-related lung 
cancer deaths per year. NIOSH (May 2003) identified over 10,000 lung 
cancer deaths in the United States during 1999 based on only 20 Census 
Industry Codes (CIC). This sum was computed from ``selected states,'' 
not the entire United States. NIOSH (May 2003) also identified 300 lung 
cancer deaths among coal miners from 15 selected states.
2. Mesotheliomas
    Mesotheliomas are malignant tumors that are rapidly fatal. They 
involve thin membranes that line the chest (the pleura) and that 
surround internal organs (the peritoneum) following asbestos 
exposure.\33\ Mesotheliomas begin with a localized mass and, like other 
malignant tumors, they can spread (metastasize) to other parts of the 
body.\34\ It does not appear that smoking is a major risk factor in the 
development of mesotheliomas.\35\

    \33\ ATSDR, 2001.
    \34\ Roach et al., 2002.
    \35\ Bolton et al., 2002.

    As in cases of lung cancer and asbestosis, mesotheliomas also have 
a latency period, varying from 15 to over 40 years.\36\ Orenstein et 
al. (2000) reported an even wider range for the latency, from a minimum 
of 5 years to a maximum of 72 years. In cases involving the pleura, 
patients often complain of chest pain, breathing difficulties on 
exertion, weakness, and fatigue. Other early symptoms of this disease 
may also include weight loss and cough. As the disease progresses, 
there is increased restriction of the chest wall and highly abnormal 
respiration, often characterized by a rapid and shallow breathing 
pattern. Mesotheliomas are rapidly progressive even in the absence of 
continued asbestos exposure. Mesotheliomas have a poor prognosis in 
most patients; death typically occurs within a year or so of 
diagnosis.\37\ Thus, like lung cancer, mesotheliomas materially impair 
human health and functional capacity.

    \36\ Suzuki and Yuen, 2002.
    \37\ Bolton et al., 2002; Roach et al., 2002; Osinubi et al., 
2000; West, 2003.

    As noted by ATSDR (2001), OSHA (1986), and many others,\38\ 
mesotheliomas are extremely rare tumors, particularly in non-asbestos 
exposed individuals. OSHA (1986) has stated, `` * * * In some asbestos-
exposed occupational groups, 10 percent to 18 percent of deaths have 
been attributable to malignant mesotheliomas * * * ''. NIOSH (May 2003) 
reported that there were about 2,500 deaths due to malignant 
mesotheliomas in the United States in 1999. Steenland et al. (2003) 
estimated that there were about 2,100 deaths in the United States from 
mesotheliomas in 1997, and that, in males, 85-90 percent of these 
deaths from mesotheliomas were due to occupational asbestos exposure. 
These tumors were generally the underlying (primary) cause of death, 
and not just a contributing cause of death. NIOSH found that most 
mesothelioma deaths were included with the categories of ``all other 
industries'' (56 percent) or ``all other occupations'' (57 percent). 
For those death certificates that included a Census Industry Code 
(CIC), the most frequently recorded was ``construction.'' The 2003 
NIOSH publication, Work-Related Lung Disease Surveillance Report 2002 
(WoRLD), did not provide specific data on mesotheliomas among miners.

    \38\ Bolton et al., 2002; Britton, 2002; Carbone et al., 2002; 
Manning et al., 2002; Orenstein et al., 2000; Roach et al., 2002; 
Suzuki and Yuen, 2002.

    One commenter expressed concern that the use of perchlorate in 
explosives might be a co-factor for increasing the incidence or 
shortening the latency period for mesothelioma among miners. In 
investigating this comment, we found that perchlorate can be a 
component in explosives \39\ and that perchlorate may cause or 
contribute to thyroid disease.\40\ We found no studies linking 
perchlorate to mesotheliomas. The California State Department of Toxic 
Substances Control states that perchlorate ``* * * has not been linked 
to cancer in humans * * *''.\41\

    \39\ EPA, 2002.
    \40\ ATSDR, 1998.


3. Asbestosis
    Asbestosis is a chronic and irreversible disease caused by the 
deposition and accumulation of asbestos in the lungs. It can lead to 
substantial injury and may cause death from the build up of bands of 
scar tissue and a loss of lung elasticity (i.e., pulmonary 
fibrosis).\42\ It is not a tumor. Following exposure to asbestos, 
chronic inflammation may occur that leads to the multiplication of 
collagen-producing cells in the lung and the accumulation of thick 
collagen bundles in essential lung tissues.\43\ These structural 
changes result in a hardening or stiffening of the lungs. Physicians 
who specialize in diseases of the lung also classify asbestosis as a 
restrictive lung disease due to this loss of elasticity.

    \42\ ATSDR, 2001.
    \43\ Osinubi et al., 2000.

    In asbestosis, the lungs are unable to properly expand and contract 
during the breathing cycle and, thus, lung volumes, airflows, and 
respiratory frequencies are likely to be abnormal.\44\ Two common 
symptoms of this disease are cough and breathing difficulties. Patients 
with asbestosis may also complain of a general feeling of discomfort, 
weakness, and fatigue. Breathing difficulties, weakness, and fatigue 
are often more severe with work or exercise. As the disease progresses, 
patients begin to experience symptoms even while resting and are likely 
to become permanently disabled.\45\ Patients with severe asbestosis 
also may experience heart or circulation problems, such as heart 
enlargement. Like lung cancer and mesotheliomas, asbestosis may be 
progressive even in the absence of continued asbestos exposure. Thus, 
asbestosis, even in its earliest stages, constitutes a material 
impairment of human health and functional capacity.

    \44\ West, 2000; West, 2003.
    \45\ OSHA, 1986.

    NIOSH (May 2003) reported that there were about 1,200 asbestosis-
related deaths in the United States in 1999. Of these, asbestosis was 
the underlying cause in about a third of these deaths (400) and a 
contributing cause in the others (800). Steenland et al. (2003) 
estimated that there were about 400 deaths from asbestosis in 1997, and 
that 100 percent of these asbestosis-deaths were due to occupational 
exposure. As shown by NIOSH (May 2003), the number of deaths related to 
asbestosis increased over ten-fold between 1968 and 1999. NIOSH also 
reported that these figures likely reflect improved diagnostic tools 
and the long latency period for evidence of disease that follows 
asbestos exposure.

[[Page 43960]]

    The death certificates for most individuals who died from 
asbestosis lacked the Census Industry Code (CIC) and the Census 
Occupation Code (COC). Most asbestosis deaths were classified under 
``all other industries'' (45 percent) and ``all other occupations'' (57 
percent). For those death certificates that included a CIC and a COC, 
the most frequently recorded industry and occupation were 
``construction'' (CIC = 060) and ``plumbers, pipefitters, and 
steamfitters'' (COC = 585), respectively. There were no specific data 
on asbestosis-related deaths among miners in the NIOSH WoRLD 
publication (May 2003).
4. Other Cancers
    OSHA, in its 1986 rule, reviewed epidemiologic studies of asbestos 
workers with cancer of the colon, rectum, kidney, larynx (voice box), 
throat, or stomach. Of these studies, researchers placed the greatest 
emphasis on those involving gastrointestinal cancers. OSHA concluded, 
`` * * * the risk of incurring cancers at these [other] sites is not as 
great as the increased risk of lung cancer * * *''. Thus, OSHA included 
lung and gastrointestinal cancers, and not these other cancer sites, in 
its 1986 risk assessment. MSHA believes that the statement remains true 
today, based on studies cited by ATSDR (2001) and by recent papers on 
kidney cancer,\46\ laryngeal cancer,\47\ lymphomas,\48\ and pancreatic 
cancer.\49\ We have not attempted to quantify the risks of these other 
cancers, which are small in comparison to lung cancer and 

    \46\ McLaughlin and Lipworth, 2000; Sali and Boffetta, 2000.
    \47\ Browne and Gee, 2000.
    \48\ Becker et al., 2001.
    \49\ Ojajarvi et al., 2000.

5. Reversible Airways Obstruction (RAO)
    Under normal physiological conditions, oxygen and other inhaled 
chemical substances pass through a branching network of airways that 
become narrower, shorter, and more numerous as they penetrate deeper 
into the lung.\50\ The diameter of each airway has an important effect 
on its airflow. A reduction in airway diameter occurs temporarily on 
exposure to some chemical substances and permanently in some diseases. 
These reductions lead to temporary or permanent airflow limitations. A 
temporary reduction of airway diameter and the resulting difficulties 
in breathing have also been called broncho-constriction, acute airways 
constriction or obstruction, or reversible airways obstruction (RAO). 
Such constriction or obstruction typically involves airways in the mid 
to lower respiratory tract.

    \50\ West, 2000.

    Several recent studies have examined respiratory health and 
respiratory symptoms of asbestos-exposed workers.\51\ Wang et al. 
(2001) reported permanent changes in airway diameters and, thus, 
permanent airflow limitations in diseases such as asbestosis or chronic 
obstructive pulmonary disease (COPD). Although patients can recover 
from RAO, they do not recover from asbestosis or COPD, which are 
typically progressive, leading to increasingly severe illness and 
premature death.

    \51\ Delpierre et al., 2002; Eagen et al., 2002; Selden et al., 

    Delpierre et al. (2002) reported that RAO in asbestos workers was 
independent of x-ray signs of pulmonary or pleural fibrosis, as well as 
a worker's smoking status. The long-term implications of RAO are 
unknown at this time. Delpierre et al., however, encouraged physicians 
to screen asbestos workers for RAO. Lung function tests may be useful 
in the early diagnosis of asbestos-disease, especially if RAO precedes 
the development of irreversible pulmonary disease, such as asbestosis.
6. Other Nonmalignant Pleural Disease and Pleural Plaques
    The pleura is the membrane lining the chest cavity. Pleural plaques 
are discrete, elevated areas of nearly transparent fibrous tissue (scar 
tissue) and are composed of thick collagen bundles. Pleural thickening 
and pleural plaques are biologic markers reflecting previous asbestos 
exposure.\52\ They appear opaque on radiographic images and white to 
yellow in microscopic sections.\53\ The American Thoracic Society (ATS, 
2004) has described the criteria for diagnosis of non-malignant 
asbestos-related pleural disease and pleural plaques.

    \52\ ATSDR, 2001; Manning et al., 2002.
    \53\ Bolton et al., 2002; Manning et al., 2002; Roach et al., 
2002; Peacock et al., 2000; ATSDR, 2001.

    Pleural plaques are the most common manifestation of asbestos 
exposure.\54\ Only rarely do they occur in persons who have no history 
or evidence of asbestos exposure. Pleural thickening and pleural 
plaques may occur in individuals exposed to asbestos in both 
occupational settings, such as miners, and non-occupational settings, 
such as family members. For example, the prevalence of pleural plaques 
ranges from 0.53 percent to 8 percent in environmentally exposed 
populations, such as the residents of Libby, Montana; 3 percent to 14 
percent in dockyard workers; and up to 58 percent among insulation 

    \54\ Cotran et al., p. 732-734, 1999; Peacock et al., 2000.

    Pleural plaques may develop within 10-20 years after an initial 
asbestos exposure \55\ and slowly progress in size and amount of 
calcification, independent of any further exposure. There is no 
evidence that pleural plaques undergo malignant degeneration into 
mesothelioma.\56\ Pleural thickening and pleural plaques, however, may 
impair lung function and may precede chronic lung disease that develops 
in some individuals.\57\ Rudd (1996), for example, reported that the 
incidence of lung cancer in patients with pleural plaques is higher 
than that of other patients. These plaques are also part of the 
clinical picture of asbestosis.

    \55\ Bolton et al., 2002; OSHA, 1986.
    \56\ Peacock et al., 2000; West, 2003.
    \57\ Schwartz et al., 1994.

7. Asbestos Bodies
    Some asbestos-exposed individuals may expel asbestos fibers from 
the lungs with a coating of iron and protein. These collections of 
coated fibers, found in sputum or broncho-alveolar lavage (BAL) fluid, 
are called asbestos bodies or ferruginous bodies.\58\ Like pleural 
thickening and pleural plaques, these bodies indicate prior asbestos 

    \58\ ATSDR, 2001; Peacock et al., 2000.

D. Support From Toxicological Studies of Human Health Effects of 
Asbestos Exposure

    Many studies are available that clearly demonstrate the toxicity of 
asbestos (e.g., carcinogenicity, genotoxicity, pneumotoxicity) and 
confirm observed human responses.\59\ Studies conducted in baboons, 
mice, monkeys, and rats have all demonstrated that asbestos fibers are 
carcinogenic.\60\ OSHA's risk assessment, however, did not rely on data 
from in vivo or in vitro toxicological studies to determine the human 
health effects from exposure to asbestos. In the preamble to its 1986 
asbestos rule (51 FR 22632), OSHA stated--

    \59\ OSHA, 1986; ATSDR, 2001.
    \60\ Davis et al., 1986; Davis and Jones, 1988; Davis et al., 
(in IARC) 1980; Davis et al., 1980; Donaldson et al., 1988; 
Goldstein and Coetzee, 1990; McGavran et al., 1989; Reeves, et al., 
1974; Wagner et al., 1974, 1980; Webster et al., 1993.

    OSHA chose not [emphasis added] to use animal studies to predict 
quantitative estimates of risk from asbestos exposure because of the 
many high quality human studies available that were conducted in 
actual workplace situations * * * OSHA has supplemented the human 
data with results from the animal studies when evaluating the

[[Page 43961]]

health information and determining the significance of risk.

Because we are relying on OSHA's 1986 asbestos risk assessment for this 
proposed rule, we do not use the toxicological studies for a 
quantitative assessment of risk, but as supportive of the causative 
relationship between asbestos exposure and observed human health 
    Toxicological studies are providing important information on 
possible mechanism(s) through which asbestos causes disease. The ATSDR 
Toxicological Profile for Asbestos (updated 2001) contains a more 
detailed discussion on this topic and describes several mechanisms of 
action for asbestos. These include--
     Its direct interaction with cellular macromolecules,
     Its recruitment of pulmonary macrophages that produce 
reactive oxygen and nitrogen species, and
     Its initiation of other cellular responses (e.g., 

V. Characterization and Assessment of Exposures in Mining

    Asbestos minerals are widespread in the environment.\61\ The use of 
asbestos-contaminated crushed rocks in roads, asbestos in insulation 
and other building materials, and the release of asbestos from brakes 
on vehicles contributes to its presence in the environment. 
Occupational asbestos exposures can be much higher than the asbestos 
levels the public typically encounters.

    \61\ ATSDR, 2001.

    Miners may be exposed to asbestos in nature, as well as in 
commercial products. Mining, milling, maintenance, or other activities 
at the mine may result in the release or re-suspension of asbestos into 
the air.\62\ In some geologic formations, asbestos may be in isolated 
pockets or distributed throughout the ore. Mining operations, such as 
blasting, cutting, crushing, grinding, or simply disturbing the ore or 
surrounding earth may cause the asbestos to become airborne. Milling 
operations may transform bulk ore containing asbestiform minerals into 
respirable fibers. Similarly, other activities conducted at mine sites, 
such as removing asbestos-containing materials during renovation or 
demolition of buildings and equipment repair work,\63\ may contribute 
to a miner's asbestos exposure.

    \62\ MSHA (Bank), 1980; Amandus et al., Part I, 1987.
    \63\ EPA, 1986, 1993, April 2003.

A. Determining Asbestos Exposures in Mining

    To evaluate asbestos exposures in mines, MSHA collects personal 
exposure air samples using a personal sampling pump and a filter-
cassette assembly, composed of a 50-mm electrically conductive 
extension cowl and a 25-mm diameter mixed cellulose ester (MCE) filter. 
Following standard sampling procedures, we also submit blank filters 
for analysis. Analysts use the blanks to correct the sampling results 
for background fiber counts due to variations in the manufacturing and 
analysis of the filter.
    Since 2001, we have used contract laboratories to analyze our 
asbestos samples by PCM. The contract laboratories report analytical 
results as the fiber concentration (f/cc) for each filter analyzed. 
Then, to evaluate a miner's full-shift exposure, MSHA calculates an 8-
hour time-weighted average concentration from a consecutive series of 
individual filters.
    Several factors complicate the evaluation of personal exposure 
levels in mining. Non-asbestos particles collected on the filter can 
hide the asbestos fibers (overloading) and, as discussed earlier (see 
section II.C.2), mining samples may also contain intermediate fibers 
that are difficult to classify. (See section II.B in this preamble.)

B. Exposures From Naturally Occurring Asbestos

    Mining and milling of asbestos-contaminated ore can release fibers 
into the ambient air. Beginning in January 2000, we initiated a focused 
effort to determine the extent of asbestos exposure among miners. We 
chose 124 metal and nonmetal mines for sampling based on the following:
     Geological information linking a higher probability for 
asbestos contamination with certain types of ores or commodities.
     Historical records identifying locations of potential 
problem mines.
     Complaints from miners reporting asbestos on mine 
    Asbestos tends to accumulate during the milling process, which is 
often in enclosed buildings. The use of equipment and machinery or 
other activities in these locations may re-suspend the asbestos-
containing dust from workplace surfaces into the air. For this reason, 
we generally find higher airborne concentrations in mills than among 
mobile equipment operators or in ambient environments, such as pits. 
The following example supports this finding.
1. Asbestos-Contaminated Ore Case Study: Wollastonite
    Wollastonite is a monocalcium silicate found in the United States, 
Mexico, and Finland. It occurs as prismatic crystals that can split 
into massive-to-acicular (needle-like) fragments when processed, and is 
used mainly in ceramics.\64\

    \64\ Warheit, p. 18, 1993.

    A consumer recently sent a sample of the final bulk product from a 
wollastonite mine to a commercial laboratory for analysis. When the 
analysis indicated the presence of asbestos contamination, the consumer 
informed the mine operator. The mine operator contacted MSHA and 
informed us of this finding after their contract laboratory confirmed 
the presence of tremolite in product samples. MSHA then conducted 
industrial hygiene sampling in the mill and the pit to verify and track 
the source of the tremolite. We found that concentrations in the mill 
exceeded 2.0 f/cc as measured by PCM. Although asbestos averaged only 
about 1.3 percent of the total fibers, over half of the exposures in 
the mill exceeded 0.1 f/cc of asbestos (the OSHA 8-hour, TWA PEL). 
Miners' exposures in the pit were much lower and further analyses 
indicated that few of these samples contained asbestos.
    The mine instituted an aggressive cleanup and control policy in the 
interest of the company and their miners' health. This wollastonite 
facility provides and launders uniforms for the millers, provides 
physical examinations to miners and their families, and uses other 
administrative controls to limit take-home contamination. In addition 
to conducting personal asbestos sampling, MSHA assisted mine management 
through the following compliance assistance activities:
     Assistance in developing cleanup and monitoring 
     Discussion of hazards of asbestos exposure with miners and 
the operator.
     Identification of accredited laboratories familiar with 
mining samples to perform asbestos analyses.
     Assistance in implementation of a respiratory protection 
     Instruction in recognition and avoidance of asbestos. MSHA 
and the mine operator worked together in recognizing the problem, 
evaluating the hazard, and determining ways to control exposures. This 
case study demonstrates successful cooperation to protect the health of 

[[Page 43962]]

2. Methods of Reducing or Avoiding Miners' Exposures to Naturally 
Occurring Asbestos
    Some mine operators mining other commodities that are likely to 
contain asbestos, such as vermiculite, have stated that they are making 
an effort to avoid deposits and seams likely to contain substantial 
quantities of asbestos. They use knowledge of the geology of the area, 
visual inspections of the working face, and sample analysis to avoid 
encountering asbestos deposits, thus preventing asbestos contamination 
of their product.\65\ In addition, some mine operators have voluntarily 
adopted the OSHA 8-hour, TWA PEL (0.1 f/cc), thus reducing the 
potential for asbestos-related illness among miners.

    \65\ GETF Report, pp. 17-18, 2003.

C. Exposures From Introduced (Commercial) Asbestos

    Asbestos is an important component in some commercial products and 
may be found as a contaminant in others. Due to improved technology and 
increased awareness, however, substitutes for asbestos in products are 
available for almost all uses, and manufacturers have removed the 
asbestos from many new products.\66\ Nevertheless, there are mines, 
including coal mines, that have introduced commercial asbestos-
containing products on their property. Some of these introduced 
products may include asbestos-containing building materials, such as 
Transite[supreg] board, used during construction, rehabilitation, or 
demolition projects. Other examples of introduced commercial products 
that may contain asbestos are brake linings for mining equipment, 
insulation, joint and packing compounds, and asbestos welding blankets.

    \66\ GETF Report, pp. 12 and 15, 2003.

    Occasionally, miners report incidents of possible asbestos release 
through MSHA's Hazard Complaint Program. Inspectors also report mines 
with noticeably deteriorated asbestos-containing building materials 
(ACBM). We investigate these reported situations and take appropriate 
action. The following example describes an incident in which miners 
unsafely removed asbestos at a mining operation.
1. Introduced Asbestos Case Study: Potash
    In June 2003, eight miners removed siding on three transfer 
conveyors originally installed in 1962 at a potash mine in Utah. The 
siding was weathered and deteriorated to the point of being friable 
(crumbling). The type of siding was a commercial product named 
Galbestos[supreg], which contains 7 percent chrysotile asbestos, as 
indicated on the Material Safety Data Sheet (MSDS). Analysis of bulk 
samples of the debris left behind by the removal of the siding 
confirmed that it contained chrysotile asbestos. When the miners 
removed it without using special precautions, they released asbestos 
into the air. It is possible that these miners contaminated themselves 
with asbestos and carried it to their families and communities (i.e., 
take-home contamination).
    MSHA became aware of this asbestos-removal work when one of the 
miners made a hazard complaint to the MSHA District Office. We 
conducted an investigation and determined that the company officials 
had known of the potential asbestos hazard for at least 2 years. We 
found no asbestos in the personal air samples collected after the 
siding had been removed. Although we did not issue citations for 
overexposure to asbestos, we issued citations to the company for 
failure to implement special work procedures, failure to issue 
appropriate personal protective equipment, and failure to train the 
affected miners for the task. The mine operator took corrective action 
and we terminated these citations.
2. Methods of Reducing or Avoiding Miners' Exposures to Introduced 
(Commercial) Asbestos
    Existing Federal and state standards already address the removal of 
asbestos-containing building materials (ACBM). If the asbestos-
containing material is intact, it is preferable to leave it where it 
is. If the asbestos-containing material is worn or deteriorating, these 
standards require the use of special precautions (e.g., personal 
protective equipment, training, decontamination) to prevent or minimize 
exposure of workers and the public and contamination of the 
environment. We train our inspectors to encourage mine operators to 
have worn or deteriorating asbestos-containing products removed by 
persons specially trained to remove the asbestos-containing material 

D. Sampling Data and Exposure Calculations

    After the national publicity surrounding asbestos-related diseases 
and death among the population of Libby, Montana, MSHA closely reviewed 
and updated its asbestos-related health procedures and policies for 
metal and nonmetal mines. We then made sure these procedures and 
policies were applied consistently across the country. For example, we 
switched from a 37-mm to a 25-mm filter cassette and recommended 
appropriate flow rates and sampling times. We also allocated additional 
resources to asbestos sampling and analysis to verify and evaluate the 
extent of asbestos exposures in mining.
1. Explanation of Sampling Data and Related Calculations
    The time-weighted average (TWA) concentration (f/cc) for individual 
filters (n = 1, 2 * * *) is calculated by dividing the number of fibers 
(f) collected on the filter by the volume of air (cc) drawn through the 
filter. TWAsum is the total time-weighted average 
concentration for all filters in the series over the total sampling 
time. The exposure limits in MSHA standards are based on an 8-hour 
workday, regardless of the actual length of the shift. MSHA measures 
the miner's exposure for the entire time the miner works. We then 
calculate a full-shift airborne exposure concentration as if the fibers 
had been collected over an 8-hour shift. This allows us to compare the 
miner's exposure to the 8-hour TWA, full-shift exposure limit. MSHA 
calls this calculated 8-hour TWA a ``shift-weighted average (SWA).''
    We calculate the TWAsum and SWA exposure levels for each 
miner sampled according to the following formulas, respectively.

TWAsum = (TWA1t1 + 
TWA2t2 + * * * + TWAntn)/
(t1 + t2 + * * * + tn)
SWA = (TWA1t1 + TWA2t2 + * 
* * + TWAntn)/480 minutes


TWAn is the time-weighted average concentration for filter 
tn is the duration sampled in minutes for filter ``n''.
TWAntn is the time-weighted average concentration 
for filter ``n'' multiplied by the duration sampled for filter ``n''.
(t1 + t2 + * * * + tn) is the total 
time sampled in minutes.

MSHA defines a ``sample'' as the average 8-hour full-shift airborne 
concentration that represents an individual miner's full-shift 
    The following information from our database illustrates the 
sampling results from these calculations. For one mechanic at the 
potash mine in our previous example, MSHA used a series of three 
filter-cassettes to determine the miner's full-shift exposure. We 
sampled a total of 577 minutes. The highest TWA concentration for one 
filter-cassette in this series was 4.100 f/cc as analyzed by PCM. MSHA 
calculated the mechanic's full-shift exposure to report the fiber 
concentration as if the mechanic had received the full exposure in 8 

[[Page 43963]]

(480 minutes). The mechanic's shift-weighted average (SWA) was 1.982 f/

            Table V-1.--Example of Personal Sampling Results
                                                           PCM TWA fiber
  Mechanic sampled 6/17/2003 at 1.7 Lpm    Sampling time   concentration
                                             (minutes)        (f/cc)
Filter-cassette 1.......................             230           4.100
Filter-cassette 2.......................             252           0.016
Filter-cassette 3.......................              95           0.045
TWAsum result...........................             577           1.649
Sample (SWA) result.....................             480           1.982

2. Summary of MSHA's Asbestos Sampling and Analysis Results
    To assess exposures and present our asbestos sampling results to 
the public, we compiled our asbestos sampling data for the period 
January 1, 2000 through December 31, 2003. We formatted these data into 
four Excel[supreg] workbooks, one for each year, and placed them, 
together with additional explanatory information, on our Asbestos 
Single Source Page at

    We calculated an 8-hour full-shift exposure for each miner sampled 
from the TWA of individual filters, typically three filters per shift. 
These data include the results of 703 full-shift personal exposure 
samples, comprised of 2,184 filter-cassettes, and cover 163 industrial 
hygiene sampling visits at 125 mines (124 metal and nonmetal mines and 
one coal mine), including some mines and mills that are now closed. 
Because the last remaining asbestos mine in the United States (Joe 5 
Pit in California) closed in December 2002 and its associated mill 
(King City) closed in June 2003, we excluded those data in our 
    Of the remaining 123 mines that MSHA sampled during this 4-year 
period, 18 mines could be potentially impacted by the lowering of the 
full-shift permissible exposure limit to 0.1 f/cc as measured by PCM. 
These 18 mines have had at least one miner exposed to airborne fiber 
concentrations exceeding 0.1 f/cc during this period. Two of the 18 
mines (iron ore and wollastonite) had personal asbestos exposures 
confirmed by TEM exceeding 0.1 f/cc. Excluding the 42 samples from the 
asbestos mine and mill, 8 percent of the remaining 661 personal samples 
had 8-hour TWA, full-shift fiber concentrations greater than the 
proposed 0.1 f/cc PEL, as measured by PCM. Table V-2 below summarizes 
these sampling results.

 Table V-2.--Personal Exposure Samples, Analyzed by PCM, at Currently Active Mines \1\ by Commodity (1/2000-12/
                                                                Number (%) of                     Number (%) of
                  Commodity                      Number of    mines  >0.1 f/cc     Number of    samples  >0.1 f/
                                              mines  sampled         SWA            samples        cc SWA \2\
Rock & quarry products \3\..................              61            4 (7%)             215            7 (3%)
Vermiculite.................................               4           3 (75%)             127            5 (4%)
Wollastonite................................               1          1 (100%)              18         18 (100%)
Iron (taconite).............................              14           5 (36%)             178          17 (10%)
Talc........................................              12            1 (8%)              38            2 (5%)
Boron.......................................               2           1 (50%)               9           4 (44%)
Other \4\...................................              29       \5\ 3 (10%)              76            3 (4%)
    Total...................................             123      \6\ 18 (15%)             661          56 (8%)
\1\ Excludes data from a closed asbestos mine and mill.
\2\ MSHA uses TEM to confirm the presence of asbestos on samples showing exposures exceeding 0.1 f/cc.
\3\ Including stone, sand and gravel mines.
\4\ Coal, potash, gypsum, salt, cement, clay, lime, mica, metal ore NOS, olivine, shale, pumice, trona, perlite,
  and gold.
\5\ Coal, potash, and gypsum (Coal and potash personal exposures are due to commercially introduced fiber
  release episodes, i.e., not from a mineral found at the mine).
\6\ TEM confirmed asbestos exposures exceeding 0.1 f/cc in two of the 18 mines.

    MSHA is proposing to lower its 8-hour TWA, full-shift PEL from 2.0 
f/cc to 0.1 f/cc to provide increased protection for miners. As noted 
in OSHA's risk assessment for its 1986 asbestos rule, there is 
significant risk of material impairment of health or functional 
capacity even at this lower PEL. MSHA compliance data indicate that 
some miners' asbestos exposures have exceeded 0.1 f/cc. Available data 
from death certificates in 24 states confirm that there is asbestos-
related mortality among miners.\67\

    \67\ NIOSH World, p. E-1, 2003.

VI. The Application of OSHA's Risk Assessment to Mining

    We are applying OSHA's risk assessment to our exposure sampling 
data on miners to estimate the risk from asbestos exposure in mining. 
In response to the ANPRM, the National Mining Association (NMA) 
expressed their belief that health risk is related to fiber type and 
that OSHA's risk assessment is no longer adequate or appropriate for us 
to use for the mining industry. In developing this proposed rule, we 
evaluated studies published over the last 20 years since OSHA completed 
its risk assessment, and studies that specifically focused on asbestos 
exposures of miners. We have found that these additional studies 
confirm OSHA's conclusions.
    Section VIII of this preamble contains a summary of our findings 
from applying OSHA's quantitative assessment of risk to the mining 
industry. The Preliminary Regulatory Economic Analysis (PREA) contains 
a more in-depth discussion of our methodology and conclusions. We 
placed our PREA in the rulemaking docket and posted it on our Asbestos 
Single Source Page at We 

also placed OSHA's risk assessment in the rulemaking docket.

[[Page 43964]]

A. Summary of Studies Used by OSHA in Its Risk Assessment

    OSHA relied on eight non-mining and milling studies to estimate the 
risk of lung cancer due to asbestos exposure. They used four studies to 
estimate the risk of mesotheliomas, and two studies, involving three 
occupational cohorts, for asbestosis. We briefly review these studies 
below, since they also serve as the basis of our risk assessment. For 
completeness, we are including Table VI-1 of some mining and milling 
studies that have been conducted.
    EPA, in its Integrated Risk Information System (IRIS), presents a 
useful table summarizing data from lung cancer and mesothelioma 
studies. We extracted that portion of their table dealing with the 
studies included in OSHA's risk assessment. This is the basis for Table 
VI-1 below.

                                              Table VI-1.--Summary of Lung Cancer and Mesothelioma Studies
                                                                    Reported       Percent (%)
                                                                    average        increase in
    Human data occupational group             Fiber type        exposure  (f-yr/  cancer per  f-                         Reference
                                                                      mL)             yr/mL
                                                                       Lung Cancer

 Friction Products...................  Chrysotile.............               32            0.058  Berry and Newhouse, 1983.
Textile Products.....................  Mostly Chrysotile......               44              2.8  Dement et al., 1982.
Cement Products......................  Mixed (Amosite,                      112              6.7  Finkelstein, 1983.
Asbestos Products....................  Mixed (Amosite,                      374             0.49  Henderson and Enterline, 1979.
Textile Products.....................  Chrysotile.............              200              1.1  Peto, 1980.
Insulation Products..................  Amosite................               67              4.3  Seidman et al., 1979; Seidman, 1984.
Insulation Workers...................  Mixed (Amosite,                      300             0.75  Selikoff et al., 1979.
Cement Products......................  Mixed (Amosite,                       89             0.53  Weill et al., 1979.

Cement Products......................  Mixed (Amosite,                      108      1.2 \E\	\5\  Finkelstein, 1983.
Textile Products.....................  Chrysotile.............               67      3.2 \E\	\6\  Peto et al., 1982.
Insulation Products..................  Amosite................              400      1.0 \E\	\6\  Seidman et al., 1979; Seidman, 1984.
Insulation Workers...................  Mixed (Amosite,                      375      1.5 \E\	\6\  Selikoff et al., 1979.

1. Lung Cancer

a. Berry and Newhouse, 1983

    Berry and Newhouse (1983) conducted a retrospective mortality study 
(1942-1980) using data from an English factory that manufactured 
asbestos-containing friction materials (e.g., brake blocks, stair 
treads). There were 13,460 workers included in this study, of which 
two-thirds were men. Most had worked in this factory for 2-10 years. 
The asbestos exposures generally involved chrysotile, although this 
site also had used crocidolite for two brief periods, one from 1922-
1933 and a second from 1939-1944.
    Personal air sampling for the assessment of asbestos concentrations 
in this factory began in 1968. Fiber levels for time periods prior to 
1968 were ``estimated by reproducing earlier work conditions using 
detailed knowledge of when processes were changed and exhaust 
ventilation introduced.'' Asbestos fiber concentrations were determined 
over four time periods: Pre-1931, 1932-1950, 1951-1969, and 1970-1979. 
Before 1931, asbestos levels typically exceeded 20 f/mL throughout the 
factory. From 1932-1969, asbestos levels decreased and most exposures 
ranged from 2-5 f/mL. After 1970, levels decreased to below 1 f/mL.
    Berry and Newhouse (1983) did not detect excessive mortality at 
this factory over the period 1942 to 1980. OSHA noted, however, the 
relatively short duration of employee exposures and the short follow-up 
period (e.g., less than 20 years for 33 percent of the men). In the 
preamble to their 1986 asbestos rule, OSHA stated,

* * * Because of the short follow-up period used, OSHA does not 
believe that the non-significant increases in lung cancer mortality 
found by these investigators [Berry and Newhouse] contradict the 
findings from other studies which show that low-level exposure to 
asbestos has resulted in excessive mortality from lung cancer * * *

b. Dement et al., 1982

    Dement et al. (1982) conducted a retrospective cohort mortality 
(1930-1975) study of 768 men. These men had worked in an asbestos 
textile factory located in South Carolina where ``only an insignificant 
quantity of asbestos fiber other than chrysotile was ever processed.'' 
The men in this study had at least 1 month of employment between 
January 1, 1940 and December 31, 1965. Dement et al. then followed the 
cohort for another 10 years.
    Air samples were collected in this factory between 1930 and 1975 to 
determine asbestos levels. Impinger samples were collected prior to 
1965; then membrane filter sampling was introduced. Membrane filter 
sampling fully replaced the impinger method in 1971. There were 193 air 
samples collected in 1930-1945, 183 in 1945-1960, and 5,576 in 1960-
1975. The estimated mean asbestos exposure levels by job and calendar 
time periods, using linear regression models, were as high as 78 f/cc 
before 1940 and generally ranged from 5-10 f/cc after 1940.
    Dement et al. (1982) demonstrated a linear dose-response 
relationship for lung cancer mortality that did not appear to have a 
threshold. They also found a linear dose-response relationship for non-
malignant respiratory disease, other than upper respiratory infection, 

[[Page 43965]]

pneumonia, or bronchitis. Like the lung cancer data, the dose-response 
relationship for non-malignant respiratory disease did not appear to 
have a threshold.
    OSHA's 1986 rulemaking considered that Dement et al.'s report of 
excess risk at low cumulative [asbestos] exposures was well supported 
because of their ``* * * careful estimation of exposure histories for 
members of the cohort * * *''.

c. Finkelstein, 1983

    Finkelstein (1983) studied a group of 328 men who worked in an 
Ontario, Canada, factory that manufactured asbestos-cement pipe and 
rock-wool insulation. Men selected to participate in this study began 
working at the factory prior to 1961 and worked for the company for at 
least 9 years. Finkelstein divided the men into three groups based on 
estimated levels of asbestos exposure: 186 in production (consistent 
exposure), 55 in maintenance (intermittent exposure), and 87 controls 
(minimal exposure). The asbestos exposures involved chrysotile and 
crocidolite, both of which the factory mixed with cement and silica. 
This study report did not indicate the proportions of asbestos and 
silica used in the cement.
    Air samples were collected to assess asbestos levels at this cement 
factory. Impinger sampling was conducted between 1943 and 1968. In 
1969-1970, the factory began to use the personal membrane filter 
sampling method and used this sampling data to classify the men who 
worked in cement production according to their probable cumulative 
asbestos exposure. They used three sub-groups (A, B, C) of estimated 
exposure ranges and means as follows:

                           Cumulative Exposure
                                                      Range       Mean
Subgroup A........................................       8-69         44
Subgroup B........................................     69-121         92
Subgroup C........................................    122-420        180

    Finkelstein also relied on detailed employment histories and 
medical records for each man in the study. Finkelstein (1983) found 
that the asbestos-exposed workers had all-cause mortality rates that 
were twice that of the general Ontario population. He also reported 
that the mortality rates due to malignancies and the deaths 
attributable to lung cancer were five and eight times those of the 
general population, respectively.

d. Henderson and Enterline, 1979

    In 1979, Henderson and Enterline published an update of their 1941-
1967 mortality study. The extended study provided data through 1973 and 
included 1,075 men who had worked for an asbestos company in the United 
States for an average of 25 years. Most of the workplace exposures 
involved chrysotile, although some involved amosite or crocidolite.
    Henderson and Enterline conducted impinger sampling to determine 
asbestos levels for this study and reported asbestos concentrations in 
millions of particles per cubic foot (mppcf). They also identified five 
cumulative exposure categories (87, 255, 493, 848, and 1,366 fiber-
years/cc) by converting their original data, reported in mppcf, to f/cc 
using a factor of 1:1.4 as discussed in the 1986 OSHA asbestos rule (51 
FR 22617).
    For the period 1941-1973, Henderson and Enterline (1979) found that 
this cohort had an overall mortality rate that was about 20 percent 
higher than that of males in the general population. This increase in 
mortality rate was mainly due to lung cancer and other respiratory 
    OSHA (1986) noted that the excess mortality risk found by Henderson 
and Enterline (1979) was less than that found by Dement et al. (1982). 
Henderson and Enterline, however, studied retired asbestos workers, 
which ``constitute a select group of survivors'' (51 FR 22617), and 
which might explain the difference in results of these two mortality 

e. Peto, 1980

    Peto (1980) continued the study of workers in an asbestos textile 
factory in England. His paper, published in 1980, was an extension of 
two earlier reports, one by Doll (1955) and a second by Peto et al. 
(1977). In this updated study (1980), Peto included 679 men who were 
hired in 1933 or later, and who had been employed by the company for at 
least 10 years by 1972. Peto divided the workers into two cohorts: 
those first exposed before 1951 (Cohort 1, n = 424 men) and those first 
exposed during or after 1951 (Cohort 2, n = 255 men). The National 
Health Central Register and factory personnel followed the workers 
until 1978. The exposures in this textile factory involved chrysotile.
    Although routine measurements of asbestos levels were not made 
prior to 1951, Peto et al. (1977) had estimated the workers' exposures 
in an earlier study. Between 1951 and 1961, a thermal precipitator was 
used to sample for asbestos, then was gradually replaced by membrane 
filters. In this study, Peto revised earlier estimates of asbestos 
exposure concentrations and reported mean levels in fibers/mL for six 
selected years as follows: 32.4 (1951), 23.9 (1956), 12.2 (1961), 12.7 
(1966), 6.7 (1971), and 1.1 (1974). Peto et al. then used these values 
to calculate cumulative exposures. The average cumulative exposure for 
men first exposed to asbestos during or after 1951 (i.e., Cohort 2) was 
200-300 fiber-years/mL.
    Peto (1980) confirmed earlier conclusions by Doll (1955) and Peto 
et al. (1977) that there was excess lung cancer mortality in this 
asbestos textile factory. Although Peto et al. (1977) suggested a dose-
response relationship for lung cancer using measurements from a static 
dust sampler, Peto did not demonstrate such a dose-response 
relationship in this later study (1980).

f. Seidman et al., 1979 (With Update to OSHA in 1984)

    Seidman et al. (1979) conducted a mortality study (1946-1977) of 
820 men who worked in an amosite factory in New Jersey. This factory 
supplied the U.S. Navy with insulation for pipes, boilers, and 
turbines. The men in this study were first employed between 1941 and 
1945 and were followed for 35 years. Due to wartime conditions, 
however, there was a changing composition of the workforce. Seidman et 
al. (1979) stated that--

    This resulted in a unique experience; men with a very limited 
duration of intense exposure to Amosite asbestos, followed by long 
observation * * *

The men were classified according to the time in which they came into 
direct contact with the amosite: Less than 1 month, 1 month, 2 months, 
3-5 months, 6-11 months, 1 year, or 2 or more years. Thus, this cohort 
is unlike those of other studies where workers were exposed to asbestos 
for long periods, often 20 or more years.
    In this amosite factory, there were no direct measurements of 
asbestos levels. The determination of asbestos concentrations was made 
solely by analogy with another factory in which air sampling was done 
in the late 1960's and in the 1970's. Seidman et al. reported that, in 
samples taken in this latter factory in October of 1971, asbestos 
counts averaged as high as 23 f/mL.
    Seidman et al. (1979) demonstrated that the amosite workers were at 
risk of developing lung cancer and dying from this disease. Seidman et 
al. (1979) concluded that--
     Prolonged follow-up is necessary to evaluate the effects 
of asbestos on

[[Page 43966]]

health, especially with lower concentration or shorter duration 
     Asbestos retained in tissues may continue to produce 
adverse effects long after the exposure may have stopped.
     The length of the latency period for asbestos-related 
diseases depends directly on the dosage and the age at which exposure 
takes place. For example, older workers will show a more pronounced and 
quicker effect than younger workers with the same level of exposure.
     The longer the time after first exposure to asbestos, the 
more pronounced the excesses in mortality.
     Reducing the asbestos exposure (lowering the dosage) can 
both delay the occurrence of adverse effects (e.g., time to death) and 
lower the frequency of their occurrence (e.g., fewer deaths).
    In 1984, Seidman updated his earlier work by adding 593 cases 
involving deaths that occurred 5-40 years beyond each man's first 
amosite exposure. Seidman again developed a classification scheme, but 
now he based it on cumulative exposure to amosite and not on time 
alone. The exposure categories were less than 6, 6-11.9, 12-24.9, 25-
49.9, 50-99.9, 100-149.9, 150-249.9, and 250 or more fiber-years/cc. 
Using this new information, he was able to demonstrate an exposure-
response relationship for lung cancer mortality.

g. Selikoff et al., 1979.

    Selikoff et al. (1979) conducted a mortality study (1943-1976) of 
17,800 men who belonged to the insulation workers' union. Members of 
this insulation union worked mainly in construction in the United 
States and Canada, but some worked in refineries, industrial plants, 
shipyards, and power plants. Selikoff et al. (1979) described the 
content of the asbestos insulation as follows.

    Until approximately the early 1940s, chrysotile alone was 
utilized in the manufacture of the asbestos insulation products used 
by these men. Amosite began to be used in the mid-1930s in small 
quantities but became more widely utilized during World War II and 

    The ages of men in this study ranged from 15 to over 85 years and 
Selikoff et al. (1979) established a series of ``age categories,'' each 
including a 5-year age span (e.g., 15-19 years, 20-24 years, etc.) 
Those men age 85 or older were grouped together. The investigators 
identified the time at which each man was first exposed to asbestos and 
then separated the data into a series of categories based on how long 
it had been since their first exposure (e.g., less than 20, 20-34, and 
35 or more years ago).
    Selikoff et al. (1979) reported that few measurements were made to 
assess asbestos levels in insulation work until the mid-1960's. For 
this reason, they estimated exposure levels using reconstructions of 
past work conditions and extrapolations of more current measurements to 
past conditions. They concluded that insulation workers would have been 
exposed to TWA concentrations of 4-12 f/mL.
    Selikoff et al. (1979) concluded that the asbestos insulation 
workers were at ``extraordinary increased risk of death of cancer and 
asbestosis.'' The study had found an excessive number of lung cancers 
(486) in this cohort, particularly at 15-35 years after the first 
exposure to asbestos. This figure was even more striking when compared 
to the expected number of lung cancer cases (106) for this same group 
of men.

h. Weill et al., 1979.

    Weill et al. (1979) conducted a mortality study of 5,645 men who 
had at least 1 month of continuous employment before January 1, 1970 in 
one of two asbestos cement building materials plants in New Orleans, 
Louisiana. The men in this study had worked at some time during the 
1940's to the mid-1970's. The investigators followed this cohort for at 
least 20 years and found that--

    For both plants, 7 percent [of the men] were initially employed 
before 1940, 76 percent during the 1940s, and 17 percent during 1950 
to 1954. Sixty percent were employed for less than one year, 24 
percent for one to 10 years, and 16 percent for more than 10 years.

    The asbestos exposures mainly involved chrysotile, although the two 
plants also processed crocidolite and amosite. The cement products were 
comprised of about 15-28 percent asbestos and some silica. Weill et al. 
(1979), however, did not provide the proportion of silica in the 
asbestos cement mixture.
    Impinger sampling was conducted in this factory to determine 
asbestos levels. The sampling results were reported in millions of 
particles per cubic foot (mppcf). Based on sampling data, Weill et al. 
(1979) defined five categories of exposure in mppcf/year as follows: 
Less than 10, 11-50, 51-100, 101-200, and more than 200. OSHA (51 FR 
22618) converted the original data of Weill et al. (1979) from mppcf/
year to fiber-years/cc using a factor of 1:1.4, as given in the 1986 
OSHA rule (51 FR 22617). This yielded the following exposure categories 
in fiber-years/cc: Less than 14, 15-70, 71-140, 141-280, more than 280.
    Weill et al. (1979) found excess mortality due to cancers, mainly 
lung cancer, in men whose cumulative exposures were moderate (141-280 
fiber-years/cc) to high (greater than 280 fiber-years/cc). About 25 
percent of their cohort, however, was lost in the follow-up period. For 
the purpose of the study, Weill et al. assumed they were alive. This 
assumption may have led to an underestimation of lung cancer risk. For 
this reason, OSHA (51 FR 22618) stated its opinion as follows:

* * * the presence of an excess risk of mortality from lung cancer 
could not be ruled out for the cohorts in these exposure categories. 
[The other three, lower exposure categories defined by Weill et al., 
2. Mesotheliomas
    a. Finkelstein, 1983.
    We reviewed the most important aspects of this study above. (See 
section VI.A.1.) Based on death records, Finkelstein (1983) found 11 
mesotheliomas among the total of 58 deaths in his study. The mean age 
at which these men were first exposed to asbestos was 25 years, and 
their mean latency period for mesotheliomas was 25 years. The mean age 
at death was 51 years, and none was over 60 years. This demonstrates 
that death follows quickly after this disease becomes evident.
    Finkelstein noted that the rates of death from mesotheliomas were 
proportional to the magnitude of cumulative asbestos exposure, as shown 
in Table VI-2 below.

     Table VI-2.--Mesotheliomas Mortality Rates Compared to Exposure
                                             Estimated    Estimated mean
  Mesotheliomas  mortality rates  (per       exposure         exposure
            1,000 man-years)              range  (fiber-   fiber-years/
                                             years/mL)          mL)
1.9.....................................            8-69              44

[[Page 43967]]

4.9.....................................          70-121              92
11.9....................................         122-420             180

    Based on the exposure-response data, Finkelstein concluded, ``* * * 
the relation is compatible with a linear function through the origin * 
* *.'' Accordingly, Finkelstein's data suggest the lack of a threshold 
for mesotheliomas.
    b. Peto et al., 1982.
    Peto et al. (1982) evaluated mesothelioma mortality (1967-1979) in 
the same group of 17,800 insulation workers previously described by 
Selikoff et al. (1979). We reviewed the salient features of Selikoff et 
al. (1979) above. (See section VI.A.1.) Members of this insulation 
workers' union worked in the United States and Canada and were exposed 
to chrysotile and amosite.
    Peto et al. (1982) reported ``a high incidence'' of mesotheliomas 
in this cohort. There were 236 deaths from mesotheliomas, of which 87 
were pleural and 149 were peritoneal. They closely examined each man's 
age at the first asbestos exposure and the number of years since his 
first exposure. Peto et al. (1982) concluded that mesothelioma 
mortality was strongly dependent on the number of years since the first 
asbestos exposure, but was independent of the age at the first 
exposure. They stated--

    Mesothelioma death rates in asbestos workers appear to be 
proportional to the third or fourth power of time * * * Age at first 
exposure has little or no influence, however, which supports the 
multi-stage model of carcinogenesis * * * mesotheliomas may 
constitute a high proportion of cancer deaths resulting from early 
exposure to asbestos.

    Peto et al. (1982) also reviewed mesothelioma mortality data from 
several other studies in addition to those from Selikoff et al. (1979). 
They were interested in determining if they could establish a 
relationship between deaths from mesotheliomas and fiber type. Although 
there were some data to suggest that deaths from mesotheliomas were 
more common in men who worked with amphiboles (e.g., crocidolite), Peto 
et al. (1982) were cautious when drawing conclusions. They stated 

    Chemical [and physical] differences between different fibre 
types may also be important, but until carcinogenic effects of such 
differences have been demonstrated, it would seem sensible to 
concentrate on fibre dimension rather than mineral type in 
developing dose-response relationships. * * * It may therefore be 
dangerously optimistic to attribute the substantial incidence of 
pleural mesothelioma among chrysotile factory workers to occasional 
crocidolite exposure * * *

    c. Seidman et al. 1979 (With Update to OSHA in 1984).
    We reviewed the salient features of this study and its update 
above. (See section VI.A.1.) Based on death records, Seidman et al. 
(1979) found 14 mesotheliomas among the total 528 deaths in their 
study. They reported an additional three mesotheliomas in their update. 
OSHA commented that this was ``a finding of great significance given 
the rarity of the disease'' (51 FR 22617).
    d. Selikoff et al. (1979).
    The salient features of this study were reviewed above. (See 
section IV.A.1.) Based on death records, Selikoff et al. (1979) found 
38 mesotheliomas (pleural and peritoneal) in their initial cohort of 
632 asbestos insulation workers. There were 223 deaths in this part of 
their study (1943-1976). Some of these deaths from mesotheliomas 
occurred 20-34 years after the first exposure to asbestos, described by 
the authors as ``duration from onset.'' For most men who died from 
mesotheliomas, however, it was 35 or more years after their first 
    In the second and much larger cohort (n = 17,800) of Selikoff et 
al. (1979), there were 175 deaths due to mesotheliomas of the total 
2,271 deaths in this group. Some (14) of these deaths caused by 
mesotheliomas occurred 15-24 years after the first asbestos exposure, 
while most (161) were recorded 25 or more years after the first 
exposure. Selikoff et al. (1979) had been unable to provide expected 
death rates for mesotheliomas due to their rarity in the general 
population. This study demonstrated an unequivocal association between 
mesotheliomas and prior asbestos exposure. In the 25 years since this 
paper was published, there has been no evidence to the contrary.
3. Asbestosis
    a. Berry and Lewinsohn, 1979.
    Berry and Lewinsohn (1979) studied the same group of textile 
workers that was originally described by Berry et al. (1979) and, thus, 
a short summary of the original paper is presented here.
    Berry et al. (1979) studied a group of 379 men who worked in an 
asbestos textile factory located in northern England. Most of the 
worker exposures involved chrysotile, although this site also used 
crocidolite. Asbestos fiber levels were measured in this factory since 
1951 and had been estimated since 1936. Berry et al. defined two 
cohorts. One included men who were first employed between 1933 and 
1950, and were still working in this textile factory in 1966. The other 
included men who were employed after 1966, and had worked for at least 
10 years in this textile factory. Berry et al. (1979) found 
relationships between cumulative asbestos exposure and crepitations 
(abnormal lung sounds), possible asbestosis, and certified asbestosis.
    As noted above, Berry and Lewinsohn (1979) used data from the same 
textile factory as that described by Berry et al. (1979); but Berry and 
Lewinsohn (1979) defined two different cohorts. One included men who 
were first employed before 1951. The other included men first employed 
after 1950. Berry and Lewinsohn (1979) plotted the incidence of cases 
of possible asbestosis against the cumulative asbestos exposure up to 
1966. They stated--

    The data are compatible with a linear relationship through the 
origin [indicating no threshold], with no statistically significant 
difference between the two groups [cohorts].

     b. Finkelstein, 1982.
    Finkelstein (1982) studied a group of 201 men who worked in a 
factory in Ontario, Canada, that manufactured asbestos-cement pipe and 
rock-wool insulation. Finkelstein defined two subsets in his study 
population: A group of 157 production workers and a group of 44 
maintenance workers. The men selected to participate in this study 
worked in the pipe or board shop for at least one year prior to 1961 
and had been employed at least 15 years. Most of the asbestos exposures 

[[Page 43968]]

chrysotile and crocidolite, both of which were mixed with cement and 
    Between the 1940's and 1968, impinger sampling was conducted to 
assess total dust levels. In 1969/1970, the company began to conduct 
quarterly personal sampling for asbestos using the membrane filter 
method. Finkelstein used the results of such sampling as baseline 
values for various jobs.
    Of the workers in this study, 39 percent of those in production and 
20 percent of those in maintenance had certified asbestosis. 
Finkelstein demonstrated that there was a relationship between 
cumulative asbestos exposure and certified asbestosis. He describes the 
exposure-response curve as sigmoidal, a shape commonly observed in 
toxicology. The curve also appears to intersect the origin, which 
suggests a lack of threshold.

B. Models Selected by OSHA (1986) for Specified Endpoints and for the 
Determination of Its PEL and STEL

    Based on their critical review of the studies described above (see 
section VI.A), OSHA (51 FR 22631) concluded--

    * * * asbestos exposure causes lung disease, respiratory cancer, 
mesothelioma, and gastrointestinal cancer. * * * excess disease risk 
has been observed at cumulative exposures at or below those 
permitted by the existing OSHA 8-hour permissible exposure limit 
[PEL] of 2 f/cc. In addition, OSHA has made risk estimates of the 
excess mortality from lung cancer, mesothelioma, gastrointestinal 
cancer, and the incidence of asbestosis using mathematical models * 
* *

    The following is a summary of the mathematical models that OSHA 
used in its asbestos risk assessment.
1. Lung Cancer
    For lung cancer, OSHA (1986) relied on a relative risk model that 
was linear in dose, as described by the following equation:

RL = RE[1 + (KL)(f)(dt-10)]


RL = Predicted lung cancer mortality.
RE = Expected lung cancer mortality in the absence of 
asbestos exposure.
KL = Slope of the dose-response relationship for lung 
f = Asbestos fiber concentration (f/cc).
d = Duration of the exposure (minus 10 years to account for latency).

    The following list gives the KL values for the eight 
studies used by OSHA. OSHA (51 FR 22637) used KL = 0.01, the 
geometric mean of these eight studies, in their risk assessment.

                           Study                                 KL
Berry and Newhouse, 1983..................................        0.0006
Dement et al., 1982.......................................        0.042
Finkelstein, 1983.........................................        0.048
Henderson and Enterline, 1979.............................        0.0047
Peto, 1980................................................        0.0076
Seidman et al., 1979; Seidman, 1984.......................        0.045
Selikoff et al., 1979.....................................        0.020
Weill et al., 1979........................................        0.0033

2. Mesotheliomas
    For mesotheliomas, OSHA (1986) relied on an absolute risk model 
that is linear in dose, but exponentially related to the time after the 
first exposure to asbestos. The following three equations describe the 

ARM = (f)(KM)[(t-10)\3\ - (t-10-d)\3\], for t > 
10 + d
ARM = (f)(KM)[(t-10)\3\], for 10 + d > t > 10
ARM = 0, for 10 > t


RM = Excess risk of mesotheliomas.
f = Asbestos fiber concentration.
KM = Slope of the dose-response relationship for 
d = Duration of the exposure.
t = Time after the first exposure to asbestos.

    The following list gives the KM values for the four 
studies used by OSHA. OSHA (51 FR 22640 and 22642) used KM = 
1 x 10-8, the ratio of KM/KL, rather 
than KM = 2.91 x 10-8, the geometric mean of 
these four studies, to account for the bias in its analysis and avoid 
overestimation of mesotheliomas in their risk assessment.

                           Study                              KM(10-8)
Finkelstein, 1983.........................................          12
Peto et al., 1982.........................................           0.7
Seidman et al., 1979; Seidman, 1984.......................           5.7
Selikoff et al., 1979.....................................           1.0

3. Asbestosis
    For asbestosis, OSHA (1986) relied on an absolute risk model that 
was linear in cumulative dose. The following equation describes the 
lifetime incidence of asbestosis:

    RA = m(f)(d)


RA = Predicted lifetime incidence of asbestosis.
f = Asbestos fiber concentration.
d = Duration of the exposure.
m = Slope of the linear regression.

    OSHA stated (48 FR 51132), ``the best estimates of asbestosis 
incidence are derived from the Finkelstein data `` and OSHA did not 
rely on the values for the slope as determined by Berry and Lewinsohn 
(1979). Thus, based on Finkelstein's data (1982) alone, the slope (m) 
is 0.055 and the equation becomes RA = 0.055(f)(d).
    Using this linear model, OSHA also calculated estimates of lifetime 
asbestosis incidence at five exposure levels of asbestos (i.e., 0.5, 1, 
2, 5, 10 f/cc) and published Table VI-3 (48 FR 51132), which we have 
reproduced below. OSHA concluded that for lifetime exposures to 
asbestos at concentrations of 2 or 0.5 f/cc, there would be a 5 percent 
or a 1.24 percent incidence of asbestosis, respectively (48 FR 51132). 
Based on Finkelstein's linear relationship for lifetime asbestosis 
incidence, OSHA later stated (51 FR 22646) that, ``Reducing the 
exposure to 0.2 f/cc [a concentration not included in Table VI-3] would 
result in a lifetime incidence of asbestosis of 0.5%.''

                             Table VI-3.--Estimates of Lifetime Asbestosis Incidence
                                                                               Percent (%) Incidence
                    Exposure level, fiber/cc                                           Berry       Berry (first
                                                                    Finkelstein      (employed    employed after
                                                                                   before 1951)        1950)
0.5.............................................................            1.24            0.45            0.35
1...............................................................            2.49            0.89            0.69
2...............................................................            4.97            1.79            1.38
5...............................................................           12.43            4.46           *3.45
10..............................................................           24.86            8.93            6.93
Slope...........................................................           0.055           0.020           0.015

[[Page 43969]]

R\2\............................................................           0.975           0.901          0.994
* Note: 1.38 in original table was a typographical error. The text (48 FR 51132) and the regression formula
  indicate that 3.45 is the correct percent.

C. OSHA's Selection of Its PEL (0.1 f/cc)

    Using the models described above in section VI.B., OSHA estimated 
cancer mortality for workers exposed to asbestos at various cumulative 
exposures (i.e., combining exposure concentration and duration of 
exposure). These data were published in its 1986 risk assessment (51 FR 
22644), which we have reproduced in the following Table VI-4.
    It is clear from Table VI-4 that the estimated mortality from 
asbestos-related cancer decreases significantly by lowering exposure. 
This is true regardless of the type of cancer: lung, pleural, 
peritoneal, or gastrointestinal. Although excess relative risk is 
linear in dose, the excess mortality rates in Table VI-4 are not 
strictly linear in dose.\68\

    \68\ Nicholson, p. 53, 1983.

  Table VI-4.--Estimated Asbestos-Related Cancer Mortality per 100,000 by Number of Years Exposed and Exposure
                                                              Cancer Mortality per 100,000 Exposed
    Asbestos fiber concentration (fiber/cc)    -----------------------------------------------------------------
                                                     Lung        Mesothelioma   Gastrointestinal       Total
                                                 1-year exposure
0.1...........................................             7.2             6.9              0.7             14.8
0.2...........................................            14.4            13.8              1.4             29.6
0.5...........................................            36.1            34.6              3.6             74.3
2.0...........................................             144             138             14.4            296.4
4.0...........................................             288             275             28.8            591.8
5.0...........................................             360             344             36.0            740.0
10.0..........................................             715             684             71.5          1,470.5
                                                20-year exposure
0.1...........................................             139              73             13.9            225.9
0.2...........................................             278             146             27.8            451.8
0.5...........................................             692             362             69.2          1,123.2
2.0...........................................           2,713           1,408            271.3          4,392.3
4.0...........................................           5,278           2,706            527.8          8,511.8
5.0...........................................           6,509           3,317            650.9         10,476.9
10.0..........................................          12,177           6,024          1,217.7         13,996.7
                                                45-year exposure
0.1...........................................             231              82             23.1            336.1
0.2...........................................             460             164             46.0            670.0
0.5...........................................           1,143             407            114.3          1,664.3
2.0...........................................           4,416           1,554            441.6          6,411.6
4.0...........................................           8,441           2,924            844.1         12,209.1
5.0...........................................          10,318           3,547          1,031.8         14,896.8
10.0..........................................          18,515           6,141          1,851.5         26,507.5

    OSHA's PEL for asbestos was 2 f/cc in 1983. Table VI-4 shows that 
after 45 years of exposure to asbestos at this concentration, there 
would be an estimated 6,411.6 deaths (per 100,000 workers). This is the 
sum of deaths from 4,416 lung cancers, 1,554 mesotheliomas, and 441.6 
gastrointestinal cancers. By lowering its PEL to 0.1 f/cc, OSHA 
decreased the risk of cancer mortality to an estimated 336.1 deaths 
(per 100,000 workers), which is the sum of deaths from 231 lung 
cancers, 82 mesotheliomas, and 23.1 gastrointestinal cancers.
    As shown above in Table VI-3, there is also a significant reduction 
in the incidence of asbestosis by lowering exposures. For example, the 
lifetime incidence of asbestosis would be reduced from 4.97 percent 
(4,970 cases per 100,000 workers) at 2 f/cc to 1.24 percent (1,240 
cases per 100,000 workers) at 0.5 f/cc. Using the linear model 
described above [RA = 0.055(f)(d)], the incidence of 
asbestosis can also be calculated at a concentration of 0.1 f/cc (not 
included by OSHA in Table VI-4) following 45 years of exposure to 
asbestos. This yields 0.25 percent, or 250 cases per 100,000 workers. 
Thus, by lowering the 8-hour TWA PEL from 2 f/cc to 0.1 f/cc, we

[[Page 43970]]

would reduce the lifetime asbestosis risk from 4,970 cases to 250 cases 
per 100,000 exposed miners.
    Based on these reductions in cancer deaths and asbestosis cases, 
OSHA demonstrated that a lowering of the PEL below 2 f/cc would 
``substantially reduce that risk'' (51 FR 22612). OSHA also noted--

Evidence in the record `` has shown that employees exposed at the 
revised standards'' PEL of 0.2 fiber/cc [OSHA's 1986 standard] 
remain at significant risk of incurring a chronic exposure-related 
disease, but considerations of feasibility have constrained OSHA to 
set the revised PEL at the 0.2 fiber/cc level.

    When OSHA further reduced its PEL from 0.2 to 0.1 f/cc in 1994, 
this statement was still true and the PEL continued to reflect 
technical feasibility issues. OSHA stated (59 FR 40967)--

The 0.1 f/cc level leaves a remaining significant risk. However as 
discussed below [in OSHA's 1994 Final Rule] and in earlier 
documents, OSHA believes that this is the practical lower limit of 
feasibility for measuring asbestos levels reliably.

D. Applicability of OSHA's Risk Assessment to the Mining Industry

    In its asbestos emergency temporary standard, and in its proposed, 
amended, and final asbestos rules (1983, 1984, 1986, 1992, 1994), OSHA 
discussed few mining and milling studies and excluded these data in 
their risk assessment. OSHA (51 FR 22637) stated,

The distinct nature of mining-milling data (and hence the estimate 
of KL from these data) has been considered earlier. There is some 
evidence that risks in the asbestos mining-milling operations are 
lower than other industrial operations due to differences in fiber 
size. `` Thus, in determining the KL for the final rule, the data 
from mining and milling processes were not considered.

    OSHA suggested that the proportionality constants (i.e., 
KL, KM), also known as the slopes of the 
respective dose response curves, from mining and milling studies are 
lower than the slopes for the studies included in its risk assessment 
(51 FR 22632 and 22637). This difference in slopes may suggest that the 
risk of asbestos-related cancers is lower in miners and millers. 
Because there is remaining significant risk of asbestos-related cancer 
at the OSHA PEL of 0.1 f/cc, we may be accepting a higher estimate of 
risk by relying on OSHA's quantitative risk assessment that excluded 
mining and milling studies.
    Although we are relying on OSHA's risk assessment, we also reviewed 
the scientific literature to identify studies that involved the 
exposure of miners and millers to asbestos. Most of these studies were 
conducted in Canada, although some have been conducted in Australia, 
India, Italy, South Africa, and the United States. Table VI-5 lists 
some of these mining and milling studies, in chronological order, and 
gives the salient features of each study. These studies are in the 
rulemaking docket.

   Table VI-5.--Selected Studies Involving Miners Exposed to Asbestos
     Author(s), year of       Study group, type of   Major finding(s) or
         publication                asbestos            conclusion(s)
Rossiter et al., 1972.......  Canadian miners and   Radiographic changes
                               millers, Chrysotile.  (opacities) related
                                                     to age and
Becklake, 1979..............  Canadian miners and   Weak relationship
                               millers, Chrysotile.  between exposure
                                                     and disease.
Gibbs and du Toit, 1979.....  Canadian and South    Need for workplace
                               African miners,       epidemiologic
                               Chrysotile.           surveillance and
Irwig et al., 1979..........  South African         Parenchymal
                               miners, Amosite and   radiographic
                               crocidolite.          abnormalities
                                                     preventable by
                                                     reduced exposure.
McDonald and Liddell, 1979..  Canadian miners and   Lower risk of
                               millers, Chrysotile.  mesotheliomas and
                                                     lung cancer from
                                                     chrysotile than
Nicholson et al., 1979......  Canadian miners and   Miners and millers:
                               millers, Chrysotile.  At lower risk of
                                                     mesotheliomas, at
                                                     risk of asbestosis
                                                     (as factory workers
                                                     and insulators), at
                                                     risk of lung cancer
                                                     (as factory
Rubino et al., Ann NY Ac Sci  Italian miners,       Role of individual
 1979.                         Chrysotile.           susceptibility in
                                                     appearance and
                                                     progression of
Rubino et al., Br J Ind Med   Italian miners,       Elevated risk of
 1979.                         Chrysotile.           lung cancer.
Solomon et al., 1979........  South African         Sign of exposure to
                               miners, Amosite and   asbestos: Thickened
                               Crocidolite.          interlobar
McDonald et al., 1980.......  Canadian miners and   No statistically
                               millers, Chrysotile.  significant
                                                     increases in SMRs.
McDonald et al., 1986.......  U.S. miners,          A. Increased risk of
                               Tremolite.            mortality from
                                                     respiratory cancer.
McDonald et al., 1980.......  U.S. miners,          B. Increased
                               Tremolite.            prevalence of small
                                                     opacities by
                                                     retirement age.
Cookson et al., 1986........  Australian miners     No threshold dose
                               and millers,          for development of
                               Crocidolite.          radiographic
Amandus et al., 1987........  U.S. miners, and      Part I: Increased
                               millers, Tremolite-   prevalence of
                               Actinolite.           radiographic
                                                     associated with
                                                     past exposure.
Amandus and Wheeler, 1987...  U.S. miners, and      Part II: Increased
                               millers, Tremolite-   mortality from
                               Actinolite.           nonmalignant
                                                     respiratory disease
                                                     and lung cancer.
Amandus et al., 1987........  U.S. miners, and      Part III: Exposures
                               millers, Tremolite-   below 1 f/cc after
                               Actinolite.           1977, up to 100-
                                                     200X higher in
                                                     1960's and 1970's.
Armstrong et al., 1988......  Australian miners     Increased mortality
                               and millers,          from mesotheliomas
                               Crocidolite.          and lung cancer.
Enarson et al., 1988........  Canadian miners,      Increased cough,
                               Chrysotile.           breathlessness,
                                                     abnormal lung
                                                     volume and
McDonald et al., 1988.......  U.S. miners, and      Low exposure and no
                               millers, Tremolite.   statistically
                                                     significant SMRs.
McDonald et al., 1993.......  Canadian miners and   Increased SMRs for
                               millers, Chrysotile.  lung cancer and
                                                     mesotheliomas as
                                                     cohort aged.

[[Page 43971]]

Dave et al., 1996...........  Indian miners and     Higher exposures in
                               millers, Chrysotile.  surface than
                                                     underground mines;
                                                     higher exposures in
                                                     mills than mines;
                                                     restrictive lung
                                                     impairment and
                                                     parenchymal changes
                                                     more common in
McDonald et al., 1997.......  Canadian miners and   Risk of
                               millers, Chrysotile.  mesotheliomas
                                                     related to
                                                     geography and
                                                     mineralogy of
                                                     caused by
Nayebzadeh et al., 2001.....  Canadian miners and   Respiratory disease
                               millers, Chrysotile.  related to regional
                                                     differences in
                                                     fiber concentration
                                                     and not dimension.
Ramanathan and Subramanian,   Indian miners and     Increased risk of
 2001.                         millers, Chrysotile   cancer, restrictive
                               and tremolite.        lung disease,
                                                     radiologic changes,
                                                     and breathing
                                                     difficulties; more
                                                     common in milling.

    These studies of miners and millers provide further evidence of 
potential adverse health effects from asbestos exposure. MSHA found 
that many of the observations presented in these studies (e.g., age of 
first exposure, latency, radiologic changes) are consistent with those 
from studies of factory and insulation workers. The exposure to 
asbestos, a known human carcinogen, results in similar disease 
endpoints regardless of the occupation that has been studied.

E. Significance of Risk

1. Defining ``Significant'' Risk: The Benzene Case
    We (MSHA) believe that this proposed rule for asbestos meets the 
requirements set forth by the OSHA Benzene Case described below. We 
have relied on OSHA's risk assessment, the studies used by OSHA in its 
development, and our review of more recent studies and mining studies, 
which further support OSHA's findings.
    In the Benzene Case, Industrial Union Department, AFL-CIO v. 
American Petroleum Institute et al. (448 U.S. 607, 1980), the U.S. 
Supreme Court ruled that, prior to the issuance of a new or revised 
standard regulating occupational exposures to toxic materials, such as 
asbestos, OSHA is required to make two findings:
     They must determine that a ``significant'' health risk 
exists, and
     They must demonstrate that the new standard will reduce or 
eliminate that risk.
    In the preamble to its 1994 final asbestos rule (59 FR 40966, 
1994), OSHA provided an interpretation of a ``significant health 
risk''. They stated,

    OSHA has always considered that a working lifetime risk of death 
of over 1 per 1000 from occupational causes is significant. This has 
been consistently upheld by the courts.

    When OSHA lowered its PEL for asbestos from 2 to 0.2 f/cc (1986), 
and then to 0.1 f/cc (1994), they used this definition of a 
``significant health risk'' and made the two findings as outlined in 
the Benzene Case. With respect to the first finding, OSHA estimated the 
excess lifetime cancer risk to be 3.4 deaths per 1,000 workers exposed 
to asbestos at 0.1 f/cc for a working lifetime. OSHA stated (51 FR 

    The finding that a significant risk exists is supported by 
OSHA's quantitative risk assessment, which is based upon studies of 
asbestos-exposed worker populations.

    With respect to the second finding, OSHA went on to say (51 FR 

    In accordance with the second element [finding, sic] of the 
Supreme Court's Benzene decision on the determination of significant 
risk, OSHA has determined that reducing the permissible exposure 
limit for asbestos [from 2 f/cc, sic] to 0.2 f/cc is reasonably 
necessary to reduce the cancer mortality risk from exposure to 
asbestos. * * * significant risks of asbestos-related cancer 
mortality and asbestosis are not eliminated at the exposure level 
that is permitted under the new standard [0.2 f/cc, sic]; however, 
the reduction in the risk of asbestos-related death and disease 
brought about by promulgation of the new standard is both 
significant and dramatic.

    OSHA concluded that the lowering of their PEL from 0.2 to 0.1 f/cc 
would ``further reduce a significant health risk'' (59 FR 40966-40967).
2. Demonstrating Significant Health Risk for the Miner
    The Federal Mine Safety and Health Act of 1977 (Mine Act), Title I, 
section 101(a), requires MSHA

    * * * to develop, promulgate, and revise as may be appropriate, 
improved mandatory health or safety standards for the protection of 
life and prevention of injuries in coal or other mines.

    Furthermore, section 101(a)(6)(A) of the Mine Act requires MSHA to 
set health or safety standards--

    * * * on the basis of the best available evidence that no miner 
shall suffer material impairment of health or functional capacity 
even if such miner has regular exposure to the hazards * * * for the 
period of his working lifetime.

    A significant health risk exists for miners exposed to asbestos at 
our existing 8-hour full-shift exposure limit of 2 f/cc. Miners, like 
the insulation workers in the studies cited by OSHA, are at risk of 
developing lung cancer, mesotheliomas, and asbestosis. These effects 
are significant and clearly constitute a material impairment of health 
and functional capacity. They also emphasize the need for us to lower 
our PEL. By lowering the 8-hour full-shift exposure limit to 0.1 f/cc, 
we would significantly reduce the risk of asbestos-related lung 
cancers, mesotheliomas, and asbestosis.
3. Using the Experience of OSHA and Current Studies to Demonstrate 
Significant Risk
    Under the Mine Act, section 101(a)(6)(A), MSHA must base its health 
and safety standards on--

    * * * the latest available scientific data in the field, the 
feasibility of the standards, and experience gained under this and 
other health and safety laws.

    In our proposed rule for asbestos, we have relied heavily on the 
experience of OSHA, which demonstrates the feasibility of a 0.1 f/cc 
exposure limit for asbestos. We believe that this limit is technically 
and economically feasible for the mining industry. (See section VIII.B. 
Feasibility.) We also have obtained and reviewed the latest available 
scientific data on the health effects of asbestos exposure. MSHA 
concludes that these studies provide further support of the significant 
risk of

[[Page 43972]]

adverse health effects following exposure to asbestos.
    Using OSHA's risk assessment, we have demonstrated that a lowering 
of our 8-hour full-shift exposure limit from 2 to 0.1 f/cc would 
significantly reduce the risk of asbestos-related disease in miners. 
MSHA believes that other existing standards help reduce the remaining 
significant risk at this new 0.1 f/cc PEL. For example, MSHA requires 
the use of engineering and work practice controls to reduce a miner's 
exposure to the PEL and, until this concentration is reached, the use 
of an approved respirator. MSHA also requires the use of personal 
protective clothing and equipment, as necessary, for equipment repair 
and for construction or demolition activities \69\ and hazard 
communication and task training.\70\ As long as miners are likely to 
encounter asbestos, miners and mine operators will need to follow 
adequate safety procedures to ensure a reduction of exposures. We 
anticipate risk reduction to occur by the use of engineering controls 
and accepted industrial hygiene administrative controls that 
effectively avoid disturbing asbestos on mine property.

    \69\ 30 CFR 56/57.5005, 56/57.15006, and 71.701
    \70\ 30 CFR parts 46, 47, and 48.

VII. Section-by-Section Discussion of Proposed Rule

    In the ANPRM, we asked commenters for supporting information to 
help us evaluate whether or not to--
     Lower our asbestos PEL,
     Revise our analytical methods and criteria to make them 
more appropriate for the mining industry, and
     Implement safeguards to limit take-home exposures.
    We received almost 100 comments, considered the commenters' 
concerns, and discussed them in the following sections.
    To make the standard easier to read, we have divided the 
requirements in the proposed standards into three paragraphs: 
Definitions, Permissible Exposure Limits (PELs), and Measurement of 
Airborne Fiber Concentration. For Sec. Sec.  56/57.5001(b), the metal 
and nonmetal asbestos standards, we numbered the paragraphs (b)(1), 
(b)(2), and (b)(3). For Sec.  71.702, the coal asbestos standard, we 
assigned the paragraphs letters (a), (b), and (c).

A. Sections 56/57.5001(b)(1) and 71.702(a): Definitions

    Our existing definition of asbestos is consistent with several 
Federal agencies' regulatory provisions, including OSHA's. As discussed 
in section II.B of this preamble and in the existing regulatory 
language, asbestos is not a definitive mineral name, but rather a 
commercial name for a group of minerals with specific characteristics. 
Our existing standards clearly state that, ``when crushed or processed, 
[asbestos] separate[s] into flexible fibers made up of fibrils'' 
[Sec. Sec.  56/57.5001(b)]; and ``does not include nonfibrous or 
nonasbestiform minerals'' (Sec.  71.702). Although there are many 
asbestiform minerals, the term ``asbestos'' in our existing standards 
is limited to the following six (Federal Six): \71\

    \71\ ATSDR, p.136, 2001; NIOSH Pocket Guide, 2003.

     Chrysotile (serpentine asbestos, white asbestos);
     Amosite (cummingtonite-grunerite asbestos, brown 
     Crocidolite (riebeckite asbestos, blue asbestos);
     Anthophylite asbestos (asbestiform anthophyllite);
     Tremolite asbestos (asbestiform tremolite); and
     Actinolite asbestos (asbestiform actinolite).
    Substantive changes to the definition of asbestos are beyond the 
scope of this proposed rule. We recognize that there are limitations in 
the general analytical methods, such as PCM and TEM, used to identify 
and quantify the Federal Six. Without the use of more complicated and 
costly analyses, it may not always be possible to differentiate other 
chemically similar amphiboles from the Federal Six. Also, the 
International Minerals Association has proposed more specific 
nomenclature in the literature to classify some of the amphiboles.\72\ 
We decline to adopt such classifications here, because they are beyond 
the scope of this proposed rule, and propose to continue to use the 
existing regulatory designations. However, we are proposing a few 
nonsubstantive changes to the existing regulatory language to clarify 
the standard. These wording changes would have no impact on the 
minerals that we regulate as asbestos from that contained in the 
existing standards. This proposed rule would--

    \72\ Leake et al., 1997.

     Clarify the term ``amosite,'' a name tied to asbestos from 
a specific geographical region, by adding the mineralogical term 
``cummingtonite-grunerite asbestos'' parenthetically.
     Add a definition for fiber to be more consistent with 
OSHA. This change would clarify that the dimensional criteria in our 
existing standards refer to the asbestiform habit of the listed 
     Conform the asbestos standards for metal and nonmetal 
mines, surface coal mines, and the surface work areas of underground 
coal mines by using the same structure and wording in the rule text. 
For example, we retain the descriptive language ``Asbestos is a generic 
term for a number of hydrated silicates that, when crushed or 
processed, separate into flexible fibers made up of fibrils'' from the 
metal and nonmetal standards rather than the comparable language from 
the coal standards. We believe that this descriptive language assists 
mine operators in understanding the scope of the standard.
    MSHA's ANPRM did not specifically solicit information about which 
asbestiform minerals we should regulate. Even so, some commenters 
suggested that MSHA should expand its definition of asbestos to include 
other asbestiform minerals, so long as our analytical method excluded 
the counting of cleavage fragments. One commenter recommended that the 
PEL be reduced not only for the six currently regulated asbestos 
minerals, but also for other amphibole minerals in their asbestiform 
habit. NIOSH commented that cleavage fragments of the serpentine 
minerals antigorite and lizardite and amphibole minerals contained in 
the series cummingtonite-grunerite, tremolite-ferro-actinolite, and 
glaucophane-riebeckite should be counted as asbestos if they meet the 
counting requirements for a fiber (3:1 aspect ratio and greater than 5 
[mu]m in length). Another commenter asked that MSHA not include 
nonasbestiform fibrous minerals and mineral cleavage fragments when we 
perform microscopic analysis of samples.
    Most commenters did not want MSHA to make changes to the fibers 
regulated as asbestos in the existing standards. Specifically, they do 
not want us to address other asbestiform amphiboles found in mineral 
deposits because they may not pose the same health problems that 
asbestos does. Some said that it would be unreasonable and expensive to 
try to meet exposure limits for all these minerals. Other commenters at 
MSHA's public hearing in New York (2002) stated that, whatever they are 
called, these minerals cause illness.
    At this time, we decline to propose substantive changes to the 
definition of asbestos as suggested by some commenters. These changes 
are beyond the scope of this rulemaking. We will continue to monitor 
the toxicological, epidemiological, and mineralogical research studies 
and other new

[[Page 43973]]

information relevant to protecting the health of miners.

B. Sections 56/57.5001(b)(2) and 71.702(b): Permissible Exposure Limits 

    MSHA currently limits a miner's 8-hour TWA, full-shift exposure to 
2.0 f/cc over a full shift; and limits a miner's short-term exposure to 
10 f/cc over a 15-minute sampling period for metal and nonmetal miners 
and 10 f/cc for a total of one hour in an 8-hour day for miners at 
surface work areas of coal mines. We are proposing to adopt OSHA's 8-
hour TWA, full-shift exposure limit of 0.1 f/cc and their 30-minute 
excursion limit of 1.0 f/cc for the mining industry. These actions 
would reduce by almost 20-fold the risk of asbestos-related deaths from 
a lifetime exposure at MSHA's existing permissible exposure limits. The 
proposed exposure limits, however, were based on feasibility and would 
not completely eliminate the risk. We believe that the proposed 
excursion limit would help reduce the residual risk from long-term 
exposure at the 0.1 f/cc 8-hour TWA, full-shift exposure limit.
    As noted by the OIG, the continued occurrence of asbestos-related 
diseases and deaths among miners emphasizes the need to reduce asbestos 
exposures. MSHA's recent field sampling data (2000 through 2003) show 
that 2 percent of the total number of MSHA's samples exceed OSHA's PEL 
of 0.1 f/cc based on TEM analysis. This same data indicate that 10 
percent of the samples exceed OSHA's PEL of 0.1 f/cc based on PCM.
    MSHA's asbestos ANPRM requested information to help us determine 
appropriate exposure limits for the mining industry, considering the 
health risk and technological and economic feasibility. We specifically 
asked what would be an appropriate agency action considering these 
levels, and if OSHA's asbestos exposure limits would afford sufficient 
protection to miners. Most commenters supported our adoption of OSHA's 
exposure limits.
    As discussed below in section VII.C of this preamble, we are 
proposing to incorporate the generic elements of PCM analytical methods 
for asbestos exposure monitoring by referencing Appendix A of OSHA's 
asbestos standard (29 CFR 1910.1001). Appendix A lists both NIOSH 7400 
and OSHA ID 160 as examples of analytical methods that meet the 
equivalency criteria in OSHA's asbestos standard. The evaluation or 
inclusion of other protocols that deviate from the criteria for 
counting fibers in our existing standards is beyond the scope of this 
1. Sections 56/57.5001(b)(2)(i) and 71.702(b)(1): 8-Hour Time-Weighted 
Average (TWA), Full-Shift Exposure Limit
    Our sampling results indicate that there is not widespread 
overexposure to asbestos in the mining industry. Recognizing this low 
exposure, many industry commenters generally supported reducing the PEL 
for asbestos to the OSHA level of 0.1 f/cc, if MSHA also ensured that 
the analytical method only counted asbestos fibers. Labor 
representatives supported reducing the PEL for asbestos to the OSHA 
level of 0.1 f/cc and recommended that MSHA propose additional 
requirements from the OSHA asbestos standard.
    Even though there was general agreement among the commenters to the 
ANPRM that MSHA should adopt OSHA's asbestos exposure limits, some 
commenters from a community association expressed concern about 
asbestos originating at a local mine. They seemed concerned not only 
with the health of miners, but also with exposures of people in 
relative proximity to the mining operations. They believe that any 
level of airborne asbestos is unacceptable.
    While we are concerned about the spread of asbestos from mine sites 
into the atmosphere, asbestos occurs naturally in many types of soils 
and ore bodies. Although comments concerning the asbestos exposure of 
those living close to a mining operation fall outside the scope of this 
rule, the proposed reduction in the permissible exposure limits may 
reduce environmental levels as well.
    We are proposing an 8-hour TWA, full-shift exposure limit of 0.1 f/
cc. This limit would significantly reduce the risk of material 
impairment of health or functional capacity for miners exposed to 
2. Sections 56/57.5001(b)(2)(ii) and 71.702(b)(2): Excursion Limit
    As previously discussed, asbestos poses a long-term health risk to 
exposed workers. There are no toxicological data identifying a ``dose-
rate'' \73\ health effect from exposure to airborne concentrations of 
asbestos. ``Dose-rate'' effect means that a specific dose can cause 
different health problems depending on the length of exposure. For 
example, asbestos does not seem to have a ``dose-rate'' effect because 
exposure to a high concentration over a short time period poses no 
greater risk of an adverse health effect than if the worker received 
the same dose at a lower concentration over a longer time period. An 
excursion limit sets boundaries for peak episodes of exposure that are 
not based on toxicological data. We are proposing an excursion limit 
for asbestos to help maintain the average airborne concentration below 
the full-shift exposure limit. For example, the 8-hour, TWA airborne 
asbestos concentration would be 0.06 f/cc for miners exposed to one 30-
minute excursion per day at 1.0 f/cc and 0.13 f/cc for miners exposed 
to two 30-minute excursions per day at 1.0 f/cc.

    \73\ OSHA (51 FR 22709), 1986.

    In the ANPRM, we requested comments on an appropriate level for a 
short-term exposure limit (67 FR 15134). We specifically asked whether 
adopting the OSHA limit of 1 f/cc over 30 minutes would afford 
sufficient protection to miners in light of the health risk and the 
technical and economic feasibility of such a limit. Commenters offered 
no objections to adopting OSHA's excursion limit for airborne asbestos, 
and some agreed that this level is appropriate.
    a. OSHA's Short-Term Exposure Limit.
    When OSHA issued its 1986 asbestos standard, it decided not to 
issue an explicit short-term exposure limit (STEL). OSHA stated the 
basis for its decision (51 FR 22709) as follows.

    To summarize, OSHA is not promulgating a short-term exposure 
limit for asbestos because toxicological and dose-response evidence 
fail to show that short-term exposure to asbestos is associated with 
an independent or greater adverse health effect than is exposure to 
the corresponding 8-hour TWA level; that is, there is no evidence 
that exposure to asbestos results in a ``dose-rate'' effect. This is 
reflected in OSHA's risk models for lung cancer and mesothelioma, 
which associate health risk with cumulative dose. The decision not 
to promulgate a short-term exposure limit for asbestos is consistent 
with OSHA's recent policy decision described in the Supplemental 
Statement of Reasons for the Final Rule for Ethylene Oxide (50 FR 
64) in which OSHA established that short-term exposure limits for 
toxic substances are not warranted in the absence of health evidence 
demonstrating a dose-rate effect.

    OSHA's decision not to issue a STEL was challenged in Public 
Citizen Health Research Group v. OSHA (796 F.2d 1505), 1986. The U.S. 
Court of Appeals for the District of Columbia held that the 
Occupational Safety and Health Act compels OSHA to adopt a short-term 
limit, if the rulemaking record shows that it would further reduce a 
significant health risk and is feasible to implement, regardless of 
whether the record supports a ``dose-rate'' effect. Subsequently, OSHA 
found that

[[Page 43974]]

compliance with a short-term limit would further reduce a significant 
health risk remaining after complying with the 8-hour TWA, full-shift 
exposure limit. OSHA also found that the lowest excursion level which 
is feasible both to measure and to achieve primarily through 
engineering and work practice controls is 1 f/cc measured over 30 
minutes. For these reasons, in 1988, OSHA promulgated an asbestos 
excursion limit of 1 f/cc over a sampling period of 30 minutes (53 FR 
    b. Minimum Detectable Level and Feasibility of Measuring Short-Term 
    As discussed in OSHA's 1986 asbestos final rule (51 FR 22686), the 
key factor in sampling precision is fiber loading. To determine whether 
the analytical method described in Appendix A of its asbestos standard 
could be used to analyze short-term samples, OSHA calculated the lowest 
reliable limit of quantification using the following formula:

C = [(f/[(n)(Af)])(Ac)]/[(V)(1,000)]


C is fiber concentration (in f/cc of air);
f is the total fiber count;
n is the number of microscope fields examined;
Af is the field area (0.00785 mm2) for a properly 
calibrated Walton-Beckett graticule;
Ac is the effective area of the filter (in mm2); and
V is the sample volume (liters).

    Table VII-1 was generated from the above equation. The table shows 
that 1.0 f/cc measured over 30 minutes can be reliably measured when 
pumps are used at the higher flow rates of 1.6 Lpm or more, using the 
25-mm filters.

Table VII-1.--Relationship of Sampling Method to Measurement of Asbestos
                                                           Lowest level
          Flow rate (Lpm)               Sampling time      measured (f/
                                                           cc) using 25-
                                                            mm filters
2.5...............................  15 minutes..........            1.05
2.0...............................  ....................            1.31
1.6...............................  ....................            1.63
1.0...............................  ....................            2.61
0.5...............................  ....................            5.23
2.5...............................  30 minutes..........            0.51
2.0...............................  ....................            0.65
1.6...............................  ....................            0.82
1.0...............................  ....................            1.31
0.5...............................  ....................            2.61

    We recognize that in some situations, such as low background dust 
levels, ower exposures could be measured; however, the risk of 
overloading the filter with debris increases when using the higher flow 
rates. We can be confident that we are measuring the actual airborne 
concentrations of asbestos, within a standard sampling and analytical 
error (25 percent), when we use the minimum loading 
suggested by the OSHA Reference Method (29 CFR 1910.1001, Appendix A). 
The excursion limit of 1.0 f/cc for 30 minutes is the lowest 
concentration that we can measure reliably for determining compliance 
with the excursion limit.
    Some commenters supported MSHA's adoption of OSHA's asbestos 
excursion limit of 1.0 f/cc for 30-minutes. Many other commenters 
offered no objections, choosing to remain silent on this issue. We have 
considered the comments and are proposing an asbestos excursion limit 
of 1.0 f/cc over a minimum sampling time of 30 minutes.

C. Sec. Sec.  56/57.5001(b)(3) and 71.702(c): Measurement of Airborne 
Fiber Concentrations

    We currently require asbestos samples to be analyzed by PCM for the 
initial determination of exposure and compliance with the PELs. We are 
proposing to retain this requirement for PCM analysis. The proposed 
rule would require fiber concentration to be determined by PCM using a 
method statistically equivalent to the OSHA Reference Method in OSHA's 
asbestos standard (29 CFR 1910.1001, Appendix A).
    The OIG recommended that we use TEM for the initial analysis of 
samples collected to evaluate a miner's personal exposure to asbestos. 
In our 2002 asbestos ANPRM, we requested information to help us 
determine the benefits and feasibility of changing our asbestos 
analytical method from PCM to TEM for evaluating a miner's exposure to 
asbestos. For the reasons discussed in this preamble, we cannot justify 
using a TEM analytical method for the initial determination of 
compliance with our asbestos PELs.
1. Brief Description and Comparison of Three Analytical Techniques
    To ease understanding of the discussion that follows, this section 
briefly describes the three analytical techniques that MSHA has used 
for analyzing asbestos samples. All three techniques involve counting 
fibers. MSHA has used--
     Phase contrast microscopy (PCM) on air samples to 
determine a miner's exposure for comparison with our permissible 
exposure limits (PELs) for asbestos.
     Transmission electron microscopy (TEM) on the same air 
samples analyzed by PCM when we need to confirm the presence of 
asbestos and distinguish asbestos from other fibers in the sample.
     Polarized light microscopy (PLM) to analyze bulk samples 
collected from an area suspected of having asbestos in the ore or dust, 
not for air samples collected to determine a miner's exposure.
    Table VII-2 below presents a brief summary of various features of 
these three analytical techniques. The values listed are approximate.

      Table VII-2.--MSHA's Comparison of Three Analytical Techniques \74\ Used to Analyze Asbestos Samples
               Criteria                          PCM                      TEM                      PLM
Magnification........................  Up to 1,000X; typically  Up to 1,000,000X;        Up to 1,000X; typically
                                        400-450X.                typically 10,000X.       10-45X.
Resolution...........................  0.2 [mu]m..............  0.001 [mu]m \75\.......  0.2 [mu]m.
Sample Area Examined.................  Minimum: 100 fibers &    100 fibers or 4.4 mm2    Scan entire prepared
                                        20 fields; or 100        minimum (0.06-0.4        sample (1 cm2).
                                        fields (0.157-0.785      mm2)*.
Additional information...............  None...................  Crystal structure &      Refractive index.
                                                                 elemental composition.
Microscope cost......................  $1,500-$2,000..........  $200,000-$300,000......  $1,500-$2,000.
Analysis cost/filter.................  $10-$15................  $100-$400..............  $10-$15.
Analysis time/filter.................  0.25-0.5 hour..........  3-4 hours or more......  0.25-0.5 hour.

[[Page 43975]]

Degree of expertise of analysts......  Requires a moderate      Requires a high level    Requires a moderate
                                        level of expertise; 40   of expertise and         level of expertise; 40
                                        hours training minimum.  experience.              hours training
* NIOSH 7402 depends on loading: light-40 fields; medium-40 fields or 100 fibers; heavy-6 fields and 100 fibers.

2. Fiber Identification Using Transmission Electron Microscopy (TEM)
    a. Advantages and Disadvantages of TEM Analysis
    The transmission electron microscope (TEM), equipped with an energy 
dispersive x-ray spectrometer (EDS) and using selected area electron 
diffraction (SAED) is generally capable of identifying the mineralogy 
of individual asbestos fibers. Even so, TEM does not always have 
sufficient precision to make definitive distinctions between closely 
related minerals, such as between winchite 
)2] and tremolite 
].\76\ Because electron microscopes provide greater magnification and 
greater image clarity, including sharper three-dimensional images than 
light microscopes, TEM can detect fibers that are undetectable using 
PCM. Routine use of TEM analysis, however, would have some significant 

    \74\ MSHA's summary of its literature reviews and experience.
    \75\ Clark, p. 5, 1977.
    \76\ Leake et al., 1997.

     Epidemiological data correlating TEM asbestos exposure 
levels with asbestos-related diseases is not available for conducting a 
new risk assessment.
     TEM analysis is time consuming and expensive, requiring 
highly skilled personnel for instrument operation and data 
interpretation, especially when applied as the primary analytical 
     Few facilities offer TEM analysis for asbestos air samples 
collected in a mining environment.
    Another disadvantage of TEM is that it uses an even smaller amount 
of sample than is used in PLM or PCM analysis. Asbestos fibers may not 
be present in the small portion of sample examined under the electron 
microscope, even when it is present in the larger sample examined by 
PLM or PCM. Despite its disadvantages, TEM allows us to better identify 
asbestos minerals in air samples collected in a mine.
    b. Use of TEM to Determine Compliance with MSHA's PELs.
    The OIG recommended that MSHA use TEM for its initial analysis to 
determine if an asbestos sample is over the PEL. MSHA believes that 
analyzing an airborne dust sample from a mine, which might contain 
asbestos, requires additional expertise not readily developed through 
experience analyzing samples known to contain asbestos. We recognize 
that EPA routinely uses TEM for the analysis of air samples collected 
for asbestos abatement under the Asbestos Hazard Emergency Response Act 
(AHERA) and requires the use of TEM to characterize workers' asbestos 
exposures (40 CFR part 763). MSHA currently uses TEM on a limited 
basis, when necessary, to verify the presence of asbestos in samples. 
These samples often contain few fibers among much dust and a variety of 
other interferences.
    In the ANPRM, we requested comments on the use of TEM including 
cost, availability, comparisons of PCM to TEM, and a possible 
relationship of TEM to a PEL. In response to the ANPRM, some commenters 
suggested that MSHA use TEM to augment PCM measurements. Overall, 
industry commenters did not recommend the use of TEM for the initial 
analysis of fiber samples for comparison to the PELs. Commenters did 
not dispute additional, confirmatory analysis of samples that show 
possible exposure to asbestos in excess of the PELs. NIOSH also did not 
believe that TEM should be used for routine monitoring even though they 
consider TEM a valuable tool in mineral identification. NIOSH comments 
stated the reasons for not using TEM as the primary method for 
determining compliance with the PELs as (i) the lack of health risk 
data associated with TEM, (ii) the level of expertise required, and 
(iii) the high cost.
    (i) Lack of Health Risk Data Based on TEM.
    OSHA did not use analytical results based on TEM in its original 
risk assessment for asbestos. Although attempts have been made,\77\ 
researchers have not reported a strong, consistent correlation between 
PCM and TEM analyses. The relationships that are reported are specific 
to the fiber type and environment sampled.\78\ To set a meaningful 
permissible exposure limit based on TEM analysis, we must have either--

    \77\ Snyder et al., 1987.
    \78\ Verma and Clark, 1995.

     Peer-reviewed epidemiology or toxicology studies relating 
TEM analysis and adverse health effects, or
     A predictive relationship correlating TEM and PCM for 
samples collected in a mining environment.
    (ii) Level of Expertise.
    One commenter representing an industry association at MSHA's public 
hearing in Charlottesville, Virginia (2002) testified that TEM was not 
a method for routine monitoring. This commenter also pointed out--

    * * *that very few commercial TEM labs are competent to perform 
valid analyses of the complicated mineralogical mixtures that you 
find in mining and quarrying operations.

    Another commenter at the Charlottesville public hearing testified 
that TEM is fallible. This commenter said that electron diffraction 
patterns for structurally similar minerals can be difficult to 
distinguish from one another. Each particle in the sample may be of a 
different composition and the analyst cannot assume that every particle 
with the same shape is the same mineral.
    (iii) High Cost of TEM Analysis.
    Several commenters representing an industry association each 
commented on the high cost of TEM analysis. One commenter stated that, 
because the variability of the measurement increases at the lower 
concentrations, when the PEL is lowered it is important to increase the 
frequency of monitoring and, therefore, the cost of sample analysis 
becomes an issue.
3. Phase Contrast Microscopy (PCM) for the Analysis of Personal 
Exposure Samples
    The use of PCM for quantitative analysis of samples does not 
differentiate between mineral species. There is industry concern that 
misidentification of fibers as asbestos can lead to incorrect 
conclusions, resulting in unnecessary expenses for mining companies. 
PCM counting schemes address the key problem of

[[Page 43976]]

needing to make a relatively fast, cost-effective evaluation of a 
situation in a mine so as to protect miners from danger to their 
health. PCM maintains the integrity, meaning, and usefulness of the 
analytical method for evaluating samples relative to the historic 
health data.\79\

    \79\ Wylie et al., 1985.

    a. Discussion of Microscope Properties.
    One issue commenters mentioned repeatedly concerning PCM is the 
limited resolution and magnification of light microscopes compared to 
electron microscopes.
    (i) Resolution.
    The resolution of the microscope is the smallest separation between 
two objects that will allow them to be distinctly visible. The higher 
the resolving power of a microscope, the smaller the distance can be 
between two particles and have them still appear as two distinct 
particles. Resolution is about 0.22 [mu]m using PCM and 0.00025 [mu]m 
using TEM. This means that where the analyst sees a single fiber using 
PCM, that same analyst might see a number of thinner fibers using TEM.
    (ii) Magnification.
    The level of magnification is another PCM microscopy issue. 
Magnification is the ratio of the size that the object appears under 
the microscope to its actual size. PCM analytical methods specify a 
magnification of 400 to 450 times (x) the object's actual size. The 
magnification using TEM can be 10,000X to 1,000,000X. This means that 
the analyst sees a smaller amount of the sample using TEM than when 
using PCM.
    b. Health Risk Data Based on PCM.
    Historically, asbestos samples have been analyzed by mass 
(weighing), counting (microscopy), or a qualitative property 
(spectroscopy). When recommending an exposure standard for chrysotile 
asbestos, the British Occupational Hygiene Society contended \80\ that 
the microscopic counting of particles greater than 5 [mu]m in length 
would show a relationship with the prevalence of asbestosis similar to 
those based on the mass of respirable asbestos. Many scientific papers 
have suggested that counting only fibers longer than 5 [mu]m would 
minimize variations between microscopic techniques \81\ and improve the 
precision of the results.\82\ Nonetheless, this criterion was accepted 
as an index of exposure, even though some believed that, due to their 
possible health effects, the smaller fibers should not be excluded.\83\

    \80\ Lane et al., 1968.
    \81\ ACGIH-AIHA, 1975.
    \82\ Wylie, 2000.
    \83\ ACGIH-AIHA, 1975; NIOSH, 1972.

    In recommending an asbestos standard in 1972, NIOSH suggested using 
the same size criteria that the British adopted. They also recommended 
reevaluating these criteria when more definitive information on the 
biologic response and precise epidemiologic data were developed. When 
exposure data were not obtained using PCM, NIOSH applied a conversion 
factor to the non-PCM data to estimate PCM concentrations for use as 
the basis of a recommended permissible occupational exposure level.
    A number of commenters testified (Charlottesville, 2002) that PCM 
methodology includes more than asbestos when determining fiber 
concentration in air. The commenters suggested that the lower risk seen 
in epidemiological studies relating PCM to adverse health outcomes in 
miners was possibly due to the background material inherent in air 
samples taken in a mining environment. They speculated that the 
background material had been counted and included in the estimated 
asbestos concentrations. This may have overestimated exposures and 
resulted in a dilution of the dose-response relationship presented in 
scientific publications.
    c. Subjectivity and Consistency of Counting Asbestos Fibers
    The fiber count obtained using the PCM method is dependent on 
several factors. These factors include the analyst's interpretation of 
the counting rules, the analyst's visual acuity, the optical 
performance of the microscope, and the optical properties of the 
prepared sample.\84\ Much of the variability is attributed to the 
ability of the analyst to observe and size fibers.

    \84\ Rooker et al., 1982.

    The American Industrial Hygiene Association (AIHA) Proficiency 
Analytical Testing Program (PAT), operated in cooperation with NIOSH, 
maintains a database for historical data relating to asbestos fiber 
counting using PCM. This program, begun in 1972, provides statistical 
evaluation of laboratory performance on test samples. At its inception 
in 1968, the method used by laboratories participating in this program 
was the U.S. Public Health Service method (USPHS 68).\85\ The counting 
rules for this method were vague and required little microscope 

    \85\ Schlecht and Shulman, 1995.

    Work has been done to modify the PCM method to address these 
consistency issues.\86\ Commenters to our asbestos ANPRM suggested that 
we consider thoracic sampling to minimize interference from large 
particles. Testimony at MSHA's public hearing in Charlottesville (2002) 
presented a counting technique based on the typical characteristics of 
asbestos in air. Another commenter stated that several approaches have 
been tried to remove non-asbestos minerals from samples, such as low 
temperature ashing or dissolution, but they would not be useful for 
mining samples. Another commenter suggested using a higher aspect ratio 
to increase the probability that the structures counted are fibers. 
Several commenters suggested the development of a new analytical 

    \86\ Pang, 2000; Harper and Bartolucci, 2003.

    Overall, commenters recognized that it takes far less time to 
develop expertise in counting fibers using PCM than in developing 
expertise using TEM. NIOSH has developed a 40-hour training course for 
teaching analysts to count asbestos fibers.
    The availability of analyst training courses, and the formation of 
accreditation bodies requiring laboratory quality assurance programs, 
helps minimize the variations in measurements between and within 
laboratories. Accreditation bodies require laboratories to use 
standardized analytical methods. AIHA also has the Asbestos Analyst 
Registry that specifies criteria for competence, education, and 
performance for analysts. In addition to these programs, our 
incorporation of OSHA's Appendix A would help minimize the subjectivity 
and increase consistency of measuring airborne asbestos concentrations 
by specifying core elements of acceptable analytical PCM methods.
4. MSHA's Incorporation of OSHA's Appendix A
    Commenters generally supported the use of PCM for the initial 
analysis of fiber samples for determining compliance with the PELs. 
Commenters' major concerns focused on fiber counting procedures. 
Commenters suggested that differential counting techniques be developed 
to analyze air samples for asbestos using PCM and taking into 
consideration the fiber morphology and the distributions or populations 
of distinct fiber groups with characteristic dimensions. Other 
commenters stated that particle characteristics could not reliably be 
used to differentiate fibers from cleavage fragments when examining 
relatively small numbers of fibers.

[[Page 43977]]

    In this rulemaking, we propose to continue to use PCM to determine 
asbestos concentrations. PCM was used in the development of past 
exposure assessments and risk estimates and is relatively quick and 
cost-effective. Thus, with respect to analytical methods, this proposed 
rule is not substantively different than our existing standards. We 
also have added language to allow for our acceptance of other asbestos 
analytical methods that are at least as effective in identifying 
potential overexposures.
    The OSHA Reference Method, mandatory Appendix A to the OSHA 
asbestos standard (29 CFR 1910.1001), specifies the elements of an 
acceptable analytical method for asbestos and the quality control 
procedures that laboratories performing the analysis must implement. 
Paragraph (d)(6)(iii) of OSHA's asbestos standard (29 CFR 1910.1001) 
requires employers, who must monitor for asbestos exposure, to use a 
method for collecting and analyzing samples that is equivalent to the 
OSHA Reference Method (ORM), and also describes the criteria for 
equivalency. For the purpose of this proposed rule, MSHA would consider 
a method equivalent if it meets the following criteria:

[from 29 CFR 1910.1001(d)(6)(iii)]

    (A) Replicate exposure data used to establish equivalency are 
collected in side-by-side field and laboratory comparisons; and
    (B) The comparison indicates that 90% of the samples collected 
in the range 0.5 to 2.0 times the permissible limit have an accuracy 
range of plus or minus 25 percent of the ORM results at a 95% 
confidence level as demonstrated by a statistically valid protocol; 
    (C) The equivalent method is documented and the results of the 
comparison testing are maintained.

    Appendix A of OSHA's asbestos standard lists NIOSH 7400 and OSHA 
ID-160 as examples of analytical methods that meet these criteria. In 
addition, there are other PCM analytical methods for asbestos:
     The Asbestos International Association (AIA), AIA RTM1, 
``Airborne Asbestos Fiber Concentrations at Workplaces by Light 
Microscopy (Membrane Filter Method).''
     The International Organization for Standardization (ISO), 
ISO 8672:1993(E), ``Air quality--Determination of the number 
concentration of airborne inorganic fibres by phase contrast 
microscopy--Membrane filter method.''
    MSHA recognizes that there are advantages and disadvantages of 
various PCM analytical methods, especially as they relate to the 
processing of samples collected in a mining environment. For example, 
the ASTM dilution method (D 5755-95) for overloaded samples has allowed 
laboratories to recover useable results from airborne exposure samples 
that, in the past, had been invalidated. We note that both ASTM and the 
National Stone Sand and Gravel Association are pursuing the development 
of an analytical method for asbestos in mining samples. We would 
consider analytical methods that afford a better measurement 
alternative as they become available. We believe that allowing 
statistically equivalent analytical methods would remove barriers to 
innovation and technological advancement.
    We specifically request information on additional criteria for 
equivalency for use in evaluating alternative analytical methods for 
the determination of asbestos in air samples collected in a mining 
environment. We also request information about analytical methods for 
which equivalency has already been demonstrated.
5. MSHA Asbestos Control Program
    In the ANPRM, we asked whether or not our current sampling methods 
met the needs of the mining community and how mineral dust 
interferences could be removed from mining samples. The ANPRM also 
asked for comments on other ways to reduce miners' exposures, such as 
increased awareness of potential asbestos hazards at the mine site and 
the provision of adequate protection. We also asked for suggestions on 
what educational and technical assistance MSHA could provide and what 
other factors, circumstances, or measures we should consider when 
engineering controls are unable to reduce asbestos exposure below the 
    We received some criticism concerning our sampling and analysis 
procedures from a few commenters who believed that we should develop 
specific test procedures for the sampling and analysis of bulk samples 
for the mining environment, as well as specific air sampling procedures 
(including pump flow rates, cassette types, and filter matrix). They 
also believed that we should improve our reports by including 
inspection field notes, location, purpose, and procedure followed, as 
well as descriptions of the accuracy, meaning, and limitations of the 
results. In its comments to the ANPRM, one trade association 
recommended that we maintain our current, established asbestos 
monitoring protocols with emphasis on full-shift monitoring for 
comparison to the PEL. Another trade association stated that our 
current field sampling methods are adequate for most mines and 
quarries, particularly when no significant amount of asbestos is found. 
They also suggested that respirable dust sampling using a cyclone might 
be a means to remove interfering dust from the sample. NIOSH suggested 
that we could use thoracic samplers, but that studies performed on 
their use did not include mines and further positive test results would 
be needed before they could promote their use in mining.
    We believe that our current sampling procedures are adequate and we 
are proposing to continue using them. Our current procedures, which we 
updated in 2000, specify using several, typically three, 25-mm filter-
cassettes in series to collect a full-shift sample. Depending on the 
amount of visible dust in the air, these procedures allow the setting 
of pump flow rates to optimize fiber loading and minimize or eliminate 
mixed dust overload. We are not considering the use of a cyclone to 
capture respirable dust because research indicates that larger durable 
fibers also could cause adverse health effects.
6. Bulk Sample Analysis Using Polarized Light Microscopy (PLM)
    In the ANPRM, we asked what method was most appropriate for MSHA to 
use to analyze bulk samples for asbestos in the mining industry. The 
presence of asbestos in a bulk sample does not mean that it poses a 
hazard. The asbestos must become airborne and be respirable, or 
contaminate food or water, to pose a health hazard to miners. The 
detection of asbestos in a bulk sample serves to alert mine operators, 
miners, and MSHA to the possible presence of asbestos. One mining 
association stated that air monitoring is not the preferred scheme to 
screen for possible asbestos exposure. They believe, and we agree, that 
knowledge of the geology of asbestos and identification of asbestos in 
bulk samples may be a useful step in determining whether asbestos is 
present in the ore or host rock.
    We are not proposing to use bulk samples to determine asbestos 
exposures in mining. We are requesting comments on whether MSHA's use 
of routine, periodic bulk sampling would be useful in determining 
whether or not we should take personal exposure air samples to evaluate 
miners' exposures to asbestos at mines suspected of having naturally 
occurring asbestos.
    MSHA also uses the detection of asbestos in bulk samples as a 
trigger for its compliance assistance activities. We have trained MSHA 
inspectors on ways to identify asbestos in the ore and

[[Page 43978]]

surrounding rock formations at mines and to pass this information on to 
mine operators. Analysis of samples of accumulated settled dust from a 
mill or construction debris can identify areas or activities that would 
require special precautions. After considering the results of the bulk 
sample analysis, together with its strengths and weaknesses, the mine 
operator, miners, and MSHA can take appropriate action to reduce the 
risk of exposure, which would help reduce the risk of asbestos-related 
diseases among miners.
    Analysis of bulk samples is usually performed using PLM. Commenters 
to the ANPRM expressed concern that the PLM analysis may not detect 
asbestos when it is present. A particle must be at least 0.5 [mu]m in 
diameter to refract light and many asbestos fibers are too thin to 
refract light. Asbestos may be a small percentage of the parent 
material or not uniformly dispersed in the sample and, therefore, may 
not be seen in the small portion of sample that is examined under the 
microscope. In addition, the method could detect asbestos erroneously 
because a nonasbestiform mineral could have a refractive index similar 
to one of the asbestos minerals. Another problem with identifying 
asbestos using PLM is that all varieties of a mineral show the same 
refractive index. For example, even an experienced analyst might not 
differentiate between the asbestiform and nonasbestiform varieties of a 
mineral based on their refractive indices.
    Although a trained individual may be able to identify bulk asbestos 
by its appearance and physical properties, the identification can be 
more difficult when the asbestos is dispersed in a dust sample or is 
present in low concentration in a rock. A commenter at MSHA's hearing 
in Charlottesville (2002) testified that none of the existing methods 
for bulk sample analysis (EPA, NIOSH, ASTM) were designed for complex 
mine environments.

D. Discussion of Asbestos Take-Home Contamination

    This proposed rule does not include standards to address asbestos 
take-home contamination. We recognize the important role of take-home 
exposures in contributing to asbestos disease of workers and their 
family members. We believe that a combination of enforcement and 
compliance assistance activities, together with increased education and 
training of mine inspectors, mine operators, and miners, coupled with 
the lowering of the PELs, would be effective in preventing asbestos 
take-home contamination. Mine operators are encouraged to measure the 
potential for take-home contamination and provide protective measures 
where necessary to minimize secondary take-home exposures.
1. MSHA's Request for Information
    MSHA's ANPRM for measuring and controlling asbestos exposures at 
mines included requests for information and data to help us evaluate 
what we could do to eliminate or minimize take-home contamination. We 
asked how and/or should MSHA be addressing take-home contamination. We 
also asked about provisions for the special needs of small mine 
operators and what assistance (e.g., step-by-step instructions, model 
programs, certification of private programs) we could provide. We also 
requested information on the types of protective clothing miners 
currently use when working in areas where asbestos may be present, and 
the types of preventive measures currently in use when miners leave the 
area, to prevent the spread of asbestos exposure.
2. Commenters' Responses to the Take-Home Contamination Issue in MSHA's 
Asbestos ANPRM
    Commenters expressed concern that we would apply the requirements 
in OSHA's and EPA's standards to trace levels of fibrous mineral 
exposures at mines, pits, and quarries. Many industry commenters urged 
MSHA to limit protective measures for take-home contamination to those 
activities involving known asbestos and asbestos-containing products, 
such as those regulated by OSHA and EPA. For example, commenters 
suggested that MSHA adopt appropriate provisions from the OSHA asbestos 
standard for construction workers, for asbestos abatement workers, and 
for those miners whose exposures exceed MSHA's PEL.
    Commenters cautioned MSHA to be mindful of the definitions of 
asbestos when analyzing samples to determine compliance. They also 
urged MSHA to acknowledge the presence of interferences in mining 
samples, as well as the differences between nonasbestiform amphiboles 
and their asbestos analogues. Some commenters cautioned that, unless 
MSHA constructed the provisions for reducing take-home contamination 
carefully, the consequences for the mining industry might be costly 
with little or no benefit to miners.
    NIOSH encouraged MSHA to adopt measures included in its 1995 Report 
to Congress on their Workers' Home Contamination Study Conducted under 
the Workers' Family Protection Act. Labor participants also supported 
protective measures, such as personal protective equipment and showers 
before leaving work, to prevent take-home contamination.
3. MSHA's Considerations in Making Its Decision To Use Non-Regulatory 
Methods To Address the Hazard From Take-Home Contamination
    In determining an appropriate proposed action for preventing take-
home contamination, we considered the comments to the ANPRM, OSHA's and 
EPA's requirements, and the recommendations of NIOSH and the OIG. We 
based our determination to propose to address asbestos take-home 
contamination through non-regulatory measures on the following factors:
     Existing standards requiring engineering controls for 
airborne contaminants, respiratory protection, personal protective 
clothing, hazard communication, and housekeeping, together with a lower 
PEL, would provide sufficient enforcement authority to assure that mine 
operators take adequate measures when necessary to prevent asbestos 
take-home contamination.
     There are no asbestos mines or mills currently operating 
in this country and different ore bodies of the same commodity, such as 
vermiculite mining, are not consistent in the presence, amount, or 
dispersion of asbestiform minerals. Currently, asbestos exposures in 
mining are low. As discussed in section V.D.2 of this preamble, only 
two of the 123 mines sampled for asbestos in the ore show personal 
asbestos exposures exceeding 0.1 f/cc. This is less than 2 percent of 
the sampled mines.
     Some mines with asbestos minerals in the ore or host rock 
have implemented protective measures voluntarily. MSHA experience in 
the recent past indicates that mine operators and mining companies are 
increasingly aware of asbestos hazards and have been willing to 
cooperate with MSHA to eliminate this hazard.
     The measures taken to prevent take-home contamination are 
varied, and mine operators would have the freedom to eliminate this 
hazard in a manner based on site-specific exposure measurements and the 
nature of the asbestos exposures at the mine. For example, mine 
operators could minimize or prevent asbestos take-home contamination by 
providing disposable coveralls or on-site shower facilities coupled 
with clothing changes.

[[Page 43979]]

4. MSHA's Activities for Eliminating the Risk of Asbestos Take-Home 
    We believe that mine operators and miners would take action to 
eliminate any possible recurrence of a disaster, such as that in Libby, 
Montana, if they understand the hazards and ways to minimize the risk. 
To that end, we are placing special emphasis on the potential hazard 
from asbestos take-home contamination in our enforcement, compliance 
assistance, and educational activities as follows.
    a. Enforcement Activities.
     Enforce the new, lower PELs when they become effective.
     Continue enforcement of standards applicable to providing 
special protective equipment and clothing whenever environmental 
hazards are encountered in a manner capable of causing injury or 
impairment, e.g., Sec.  56.15006.
     Ensure that mine operators provide miners, who are at risk 
of being exposed, with information about the signs, symptoms, and risk 
for developing asbestos-related illness as required by the hazard 
communication standard.
    b. Compliance Assistance.
     Continue to monitor targeted mines for the presence of 
     Encourage mine operators to comply with OSHA's asbestos 
standard, or hire professionals skilled and certified in working with 
asbestos, when they engage in construction, demolition, or renovation 
activities at the mine.
     Issue an updated Program Information Bulletin (PIB) on 
asbestos to include a greater emphasis on protective measures to reduce 
take-home contamination. We expect distribution this year.
    c. Educational Activities.
     Continue outreach to mine operators through training 
courses, informational materials, and topical local meetings.
     Issue an updated Health Hazard Information Card for miners 
this year to increase miners' awareness of the hazards of take-home 
contamination from asbestos or other asbestiform minerals and to 
suggest measures that the miners can take to prevent it.
     Continue specialized asbestos hazard and sampling training 
for mine inspectors.

E. Section 71.701(c) and (d): Sampling; General Requirements 
[Controlling Asbestos Exposures in Coal Mines]

    For surface coal mines and surface worksites at underground coal 
mines, we are proposing to add a reference to Sec.  71.702 (the 
asbestos standard for coal mines) in paragraphs (c) and (d) of Sec.  
71.701, which contain the requirements for controls and sampling. The 
existing language in Sec.  71.701(c) and (d) references the Threshold 
Limit Values (TLVs[supreg]) and excursion limits in Sec.  71.700, but 
not the asbestos exposure limits in Sec.  71.702. MSHA regulations 
currently require mine operators to control miners' exposures to 
airborne contaminants and to sample for airborne contaminants, as 
necessary, to determine when and where such controls may be needed. In 
developing this proposed rule, we determined that Sec.  71.701 was 
unclear as to its applicability to asbestos exposures. This proposed 
rule would clarify our intent that coal mine operators control miners' 
exposures to asbestos.

VIII. Regulatory Analyses

A. Executive Order (E.O.) 12866

    In our ANPRM on asbestos exposure, we specifically requested 
information, data, and comments on the costs and benefits of an 
asbestos rule, including what engineering controls and personal 
protective equipment are being used to protect miners from exposure to 
asbestos and to prevent take-home contamination. Considering the public 
comments, and MSHA data and experience, we assessed both the costs and 
benefits of this proposed rule in accordance with Executive Order 
12866. The following sections summarize the analysis of benefits and 
costs presented in the Preliminary Regulatory Economic Analysis (PREA) 
for this proposed rule. The PREA contains a full disclosure of our 
methodology and the basis for our estimates.
1. Discussion of Benefits
    The benefits of a rulemaking addressing measurement and control of 
asbestos would be the reduction or elimination of diseases arising from 
exposure to asbestos. Exposure to airborne asbestos can cause the 
development of lung cancer, mesothelioma, gastrointestinal cancer, and 
asbestosis. Other associated adverse health effects include cancers of 
the larynx, pharynx, and kidneys. A person with an asbestos-related 
disease suffers material impairment of health or functional capacity.
    a. Summary of Benefits.
    We estimate that between 1 and 19 deaths could be avoided during 
the next 65 years by lowering the 8-hour TWA, full-shift exposure limit 
from 2.0 f/cc to 0.1 f/cc. This equates to a reduction of between 9 and 
84 percent of occupationally related deaths caused by asbestos 
exposures. Additional deaths would be avoided by decreasing miners' 
exposures to short-term bursts of airborne asbestos undetectable by the 
proposed 8-hour TWA, full-shift exposure limit. We estimate that 
lowering the excursion limit from 10 f/cc over 15 minutes to 1 f/cc 
over 30 minutes would reduce the risk of death from lung cancer, 
mesothelioma, or gastrointestinal cancer by 1 additional avoidable 
death for every 1,000 miners exposed to asbestos at the proposed PELs.
    We are aware that lowering our PELs would not completely eliminate 
the risk of asbestos-related material impairment of health or 
functional capacity. We expect some additional risk reduction from mine 
operators' management directives to avoid disturbing asbestos on mine 
    b. Calculation of Deaths Avoided.
    The benefits resulting from the lowered PELs depend on several 
factors including--
     Existing and projected exposure levels,
     Age of the miner at first exposure,
     Number of workers exposed, and
     Risk associated with each exposure level.
    We estimate the number of miners currently exposed and their level 
of exposure from personal exposure information gathered during our 
inspections between January 2000 and December 2003. These data are 
available on our Web site at Section V of this 
preamble contains the characterization and assessment of exposures in 
    Laboratory results indicate that exposure concentrations are 
unevenly distributed across mines and miners. We use four fiber 
concentration levels to estimate the risk to miners. The break points 
for these exposure levels are the proposed and existing exposure 
limits. Observations show that 90 percent of the sampling results are 
below 0.1 f/cc.
    To estimate the expected number of asbestos-related deaths, we 
applied OSHA's linear, no-threshold, dose-response risk assessment 
model to our existing and proposed PELs. The upper exposure limit is 10 
f/cc because the range of information derived from the epidemiological 
studies used to determine the dose-response relationship in OSHA's 
quantitative risk assessment does not include higher levels. The 
expected reduction of deaths resulting from lowering the PELs would

[[Page 43980]]

be the differences between the expected deaths at each exposure 

    \87\ Nicholson, 1983; JRB Associates, 1983; OSHA (51 FR 22612), 
1986; OSHA (53 FR 35609), 1988; OSHA (59 FR 40964), 1994.

    OSHA estimated cancer mortality for workers exposed to asbestos and 
published these data in their 1986 final rule (51 FR 22644). We discuss 
OSHA's asbestos risk assessment in section VI of this preamble and have 
reproduced OSHA's mortality data in Table VI-4.
    c. Benefit of the Proposed 0.1 f/cc 8-hour TWA, Full-Shift Exposure 
    The current deaths from lung cancer, mesotheliomas, 
gastrointestinal cancer, and asbestosis are the result of past 
exposures to much higher air concentrations of asbestos than those 
found in mines today. The risks of these diseases still exist, however, 
and these risks are significant for miners exposed to lower air 
concentrations of asbestos. Most diseases resulting from a current 
asbestos exposure may not become evident for another 20 to 30 years. 
Most likely, the full benefits will occur over a 65-year period 
following implementation of the lower PELs. The rate at which the 
incidence of the cancers decreases depends on several factors 
     Latency of onset of cancer,
     Attrition of the mining workforce,
     Changing rates of competing causes of death,
     Dynamics of other risk factors,
     Changes in life expectancy, and
     Advances in cancer treatments.
It is not possible to quantify accurately the complete dynamics of this 
    Supplemental examination of MSHA's personal exposure samples using 
TEM analysis indicates that not all fibers counted by PCM are the 
currently regulated asbestos minerals. This is especially true for 
operations mining and processing wollastonite. We distinguish between 
different mineralogical fibers using TEM and combine this supplemental 
information with PCM information to calculate our lower estimate of 
    We estimate that there would be from 0.5 to 13.1 lung cancer deaths 
avoided, 0.2 to 4.4 mesothelioma deaths avoided, and 0.1 to 1.3 
gastrointestinal cancer deaths avoided. The total number of cancer 
deaths avoided by this rule would be the sum of cancer deaths avoided 
at all the mines included in the exposure data, that is, the mines we 
have sampled. Based on the best available information, we expect a 
reduction of between 1 and 19 deaths avoided due to lowering the 8-hour 
TWA PEL to 0.1 f/cc.
    d. Benefits of the Proposed 1.0 f/cc Excursion Limit.
    We are proposing an asbestos excursion limit of 1.0 f/cc as 
measured over a 30-minute period for metal and nonmetal miners and coal 
miners working at surface work areas. We intend that the excursion 
limit protect miners from the adverse health risks associated with 
brief fiber-releasing episodes. We anticipate that some mining 
operations will be subject to brief fiber-releasing episodes even after 
lowering airborne asbestos concentrations to the 8-hour TWA, full-shift 
exposure limit. We have insufficient data, however, to obtain a 
meaningful estimate of the frequency of these episodes, the actual 
exposure concentrations, or the numbers of miners exposed. Miners may 
encounter brief fiber-releasing episodes from exposure to commercial 
asbestos in asbestos-containing building materials (ACBM) or as settled 
dust containing asbestos; while working on equipment that may have 
asbestos-containing parts; and while drilling, dozing, blasting, or 
roof bolting in areas of naturally occurring asbestos.
    Because we have little information from short-term exposure 
measurements, we estimate the benefit of an excursion limit from the 
difference in concentration between the 8-hour TWA, full-shift exposure 
limit (0.1 f/cc) and the excursion limit averaged over the full shift 
[(1 f/cc)/(16 30-minute periods) = 0.063 f/cc]. The lifetime risk 
associated with an exposure to 0.1 f/cc from either of the three types 
of cancer is 0.00336, if first exposed at age 25 and exposure continues 
every work day at that level for a duration of 45 years. The risk 
associated with exposure to 0.063 f/cc using the same age and duration 
of exposure is 0.00212. The difference in lifetime risk is 0.00124. 
This risk equates to 1.24 additional deaths avoided for every 1,000 
miners exposed to asbestos at a concentration afforded by the proposed 
excursion limit.
    e. Further Consideration of Benefits.
    We believe that the pressure of public scrutiny and government 
intervention has prompted mine operators to take precautionary measures 
to limit miners' exposures to asbestos. If public pressures were to 
subside, and we did not have a regulation limiting exposures to 0.1 f/
cc over an 8-hour shift, we would not have a means to enforce the same 
level of protection provided in other industries.
    Enforcement of the lower PELs together with the direct support from 
the federal government in education, identification, and elimination of 
the asbestos hazard would increase awareness and attention to the 
presence of asbestos on mine property. These activities also would help 
focus efforts on preventing exposures, thus providing miners with added 
health benefits. As seen in Chart VIII-1, mining operations with ore 
containing naturally occurring asbestos seem to have reduced miners' 
exposures, perhaps due to their awareness of the lower exposure limits 
OSHA promulgated in 1986.\88\ 

    \88\ NIOSH WoRLD pp. 16-17 and 19-23, 2003.
    \89\ NIOSH WoRLD, 2003.


[[Page 43981]]


    The estimates of the cancer deaths avoided by reducing the PELs 
understate the total amount of benefit gained from this rule. These 
benefits do not include the reduced incidence of asbestosis-related 
disabilities. Asbestosis cases often lead to tremendous societal costs 
in terms of health care utilization, loss of worker productivity, and a 
decrease in the quality of life of the affected individual. Similarly, 
MSHA's analysis does not quantify benefits among groups incidentally 
exposed, such as miners' family members. We note that several published 
articles document and discuss the health effects resulting from 
exposure to asbestos incident to living with a miner.\90\

    \90\ NIOSH Publication No. 2002-113, May 2002.

    This analysis overstates health benefits to the extent that we do 
not account for differential risks posed by different types of fibers 
as identified by PCM, and differences in the cancer mortality risk for 
asbestos-exposed workers who smoke and those who do not.
2. Discussion of Costs
    The proposed rule would result in total yearly costs of about 
$136,100. The cost would be about $91,500 per year for metal and 
nonmetal mines and about $44,600 per year for coal mines. These costs 
represent less than 0.001 percent of the yearly revenues of $38.0 
billion for the metal and nonmetal mining industry and $10.1 billion 
for the surface coal mining industry.
    Table VIII-1 presents our estimate of the total yearly compliance 
costs by compliance strategy and mine size. The total costs reported 
are projected costs, in 2002 dollars, based on our knowledge, 
experience, and available information.

                                Table VIII-1.--Summary of Yearly Compliance Costs
                                                        Compliance strategy
                                 ----------------------------------------------------------------    Total for
  Metal and nonmetal mine size                                                      Removal of       metal and
                                     Selective      Wet methods        Mill         introduced    nonmetal mines
                                      mining                        ventilation       asbetos
Small (< 20).....................          $1,058          $1,235            $747          $1,750          $4,790
Large (20-500)..................           4,922           8,614          12,916          21,000          47,452
Large (>500)....................           1,641           2,871          19,001          15,750          39,264
    Total.......................           7,622          12,721          32,664          38,500          91,506

                                                        Compliance strategy
         Coal mine size                                                             Removal of    Total for coal
                                     Selective      Wet methods        Mill         introduced         mines
                                      mining                        ventilation       asbetos
Small (< 20).....................  ..............  ..............  ..............            $875            $875
Large (20-500)..................  ..............  ..............  ..............          12,250          12,250
Large (>500)....................  ..............  ..............  ..............          31,500          31,500

[[Page 43982]]

    Total.......................  ..............  ..............  ..............          44,625          44,625

B. Feasibility

    MSHA has concluded that the requirements of this proposed rule 
would be both technologically and economically feasible. This proposed 
rule is not a technology-forcing standard and does not involve 
activities on the frontiers of scientific knowledge. All devices that 
would be required by the proposed rule are already available in the 
marketplace and have been used in either the United States or the 
international mining community. We have concluded, therefore, that this 
proposed rule is technologically feasible.
    As previously estimated, the mining industry would incur costs of 
about $136,100 yearly to comply with this proposed rule. These 
compliance costs represent well less than 0.001 percent of the yearly 
revenues of the mines covered by this rule, thus providing convincing 
evidence that the proposed rule is economically feasible.

C. Alternatives Considered

    In our discussion of PELs in section VII.B of this preamble, we 
recognize that there is a remaining residual risk of adverse health 
effects for miners exposed at the proposed asbestos 8-hour TWA PEL. We 
considered proposing a lower PEL as a regulatory alternative to further 
reduce the risk of adverse health effects from a working lifetime of 
exposure. Assuming 0.05 f/cc, for example, and interpolating the data 
from OSHA's risk assessment summarized in Table VI-4 of this preamble, 
there would be about 1.68 cancer deaths per 1,000 miners exposed to 
asbestos at 0.05 f/cc for 45 years. The 1.68 cancer mortality rate is 
50 percent less than the rate of 3.36 cancer deaths per 1,000 exposed 
miners calculated for the proposed 0.1 f/cc PEL; and about 97 percent 
less than we estimate for our existing standard (64.12 cancer deaths 
per 1,000 exposed miners). We also project that reducing miner's 
exposure to an 8-hour TWA of 0.05 f/cc would reduce the expected cases 
of asbestosis to about 50 percent less than at the proposed 8-hour TWA 
    About 85 percent of the 123 sampled mines are already well in 
compliance with the 0.1 f/cc proposed PEL. We believe that, 
theoretically, almost all of the mining industry could be in compliance 
with a lower alternative PEL (0.05 f/cc 8-hour TWA). However, we cannot 
enforce an 8-hour TWA limit below 0.1 f/cc. The diversity of airborne 
particles prevalent in mining environments can interfere with sample 
analysis. Our existing standardized sampling techniques minimize 
interferences, but also impose limitations of accuracy below 
concentrations of 0.1 f/cc. We address these limitations in more detail 
in Chapter III of the PREA that accompanies this proposed rule. These 
accuracy issues make it infeasible for us to enforce a concentration 
lower than 0.1 f/cc airborne asbestos.
    Although TEM provides greater characterization of asbestos fibers 
than PCM methodology, there is no predictable relationship between PCM 
and TEM measures of exposure using either method alone. We do not know 
of a risk assessment correlating TEM measures of exposure with adverse 
health effects. TEM measurements, therefore, cannot be used as the 
basis for an occupational exposure limit at this time. Additionally, 
TEM is much more expensive and time consuming than PCM. If we were to 
analyze each of the 2,184 personal exposure filters (collected by us to 
determine full-shift asbestos exposures from 2000 through 2003) using 
TEM, rather than PCM, it would cost us about $186,000 to $852,000 more. 
The mine operator's costs would increase in so far as the operator 
would do comparable sampling. We expect the operator to sample to 
determine whether control measures are needed, what controls might be 
needed, and the effectiveness of controls when implemented. A number of 
commenters supported our continued use of PCM for the initial analysis 
of asbestos samples.
    We conclude that it is not feasible to regulate the mining industry 
below the proposed limit at this time. We welcome comments on the 
exposure limit proposed and the rationale used for choosing it over the 
alternative discussed above.

D. Regulatory Flexibility Analysis (RFA) and Small Business Regulatory 
Enforcement Fairness Act (SBREFA)

    Based on our data, our experience, and information submitted to the 
record, we determined, and here certify, that this proposed rule would 
not have a significant economic impact on a substantial number of small 
entities. The PREA for this proposed rule (RIN: 1219-AB24), Measuring 
and Controlling Asbestos Exposure, contains the factual basis for this 
certification as well as complete details about data, equations, and 
methods used to calculate the costs and quantified benefits. We have 
placed the PREA in the rulemaking docket and posted it on MSHA's Web 
site at

E. Other Regulatory Considerations

1. The National Environmental Policy Act of 1969 (NEPA)
    We have reviewed this proposed rule in accordance with the 
requirements of NEPA (42 U.S.C. 4321 et seq.), the regulations of the 
Council on Environmental Quality (40 CFR 1500), and the Department of 
Labor's NEPA procedures (29 CFR 11) and have assessed its environmental 
impacts. We found that this proposed rule would have no significant 
impact on air, water, or soil quality; plant or animal life; the use of 
land; or other aspects of the human environment.
2. Paperwork Reduction Act of 1995
    This proposed rule contains no information collection or 
recordkeeping requirements. Thus, there are no additional paperwork 
burden hours and related costs associated with the proposed rule. 
Accordingly, the Paperwork Reduction Act requires no further agency 
action or analysis.
3. The Unfunded Mandates Reform Act of 1995
    This proposed rule does not include any Federal mandate that may 
result in increased expenditures by State, local, or tribal 
governments; nor would it significantly or uniquely affect small 
governments. It would not increase private sector expenditures by more 
than $100 million annually. Accordingly, the Unfunded Mandates Reform 
Act requires no further agency action or analysis.

[[Page 43983]]

4. Treasury and General Government Appropriations Act of 1999, (Section 
654: Assessment of Impact of Federal Regulations and Policies on 
    This proposed rule would have no affect on family well-being or 
stability, marital commitment, parental rights or authority, or income 
or poverty of families and children. Accordingly, the Treasury and 
General Government Appropriations Act requires no further agency 
action, analysis, or assessment.
5. Executive Order 12630: Government Actions and Interference With 
Constitutionally Protected Property Rights
    This proposed rule would not implement a policy with takings 
implications. Accordingly, Executive Order 12630 requires no further 
agency action or analysis.
6. Executive Order 12988: Civil Justice Reform
    We have drafted and reviewed this proposed rule in accordance with 
Executive Order 12988. We wrote this proposed rule to provide a clear 
legal standard for affected conduct and carefully reviewed it to 
eliminate drafting errors and ambiguities, thus minimizing litigation 
and undue burden on the Federal court system. MSHA has determined that 
this proposed rule would meet the applicable standards in section 3 of 
Executive Order 12988.
7. Executive Order 13045: Protection of Children From Environmental 
Health Risks and Safety Risks
    This proposed rule would have no adverse impact on children. This 
proposed asbestos standard might benefit children by reducing 
occupational exposure limits, thus reducing their risk of disease from 
take-home contamination. Accordingly, Executive Order 13045 requires no 
further agency action or analysis.
8. Executive Order 13132: Federalism
    This proposed rule would not have ``federalism implications,'' 
because it would not ``have substantial direct effects on the States, 
on the relationship between the national government and the States, or 
on the distribution of power and responsibilities among the various 
levels of government.'' Accordingly, Executive Order 13132 requires no 
further agency action or analysis.
9. Executive Order 13175: Consultation and Coordination With Indian 
Tribal Governments
    This proposed rule would not have ``tribal implications,'' because 
it would not ``have substantial direct effects on one or more Indian 
tribes, on the relationship between the Federal government and Indian 
tribes, or on the distribution of power and responsibilities between 
the Federal government and Indian tribes.'' Accordingly, Executive 
Order 13175 requires no further agency action or analysis.
10. Executive Order 13211: Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use
    In accordance with Executive Order 13211, we have reviewed this 
proposed rule for its impact on the supply, distribution, and use of 
energy. This proposed rule would regulate both the coal and metal and 
nonmetal mining sectors. Because this proposed rule would result in 
negligible yearly costs of less than 0.001 percent of revenues to the 
coal mining industry, the proposed rule would neither significantly 
reduce the supply of coal nor significantly increase its price. 
Regulation of the metal and nonmetal sector of the mining industry has 
no significant impact on the supply, distribution, or use of energy.
    This proposed rule is not a ``significant energy action,'' because 
it would not be ``likely to have a significant adverse effect on the 
supply, distribution, or use of energy'' ``(including a shortfall in 
supply, price increases, and increased use of foreign supplies).'' 
Accordingly, Executive Order 13211 requires no further agency action or 
11. Executive Order 13272: Proper Consideration of Small Entities in 
Agency Rulemaking
    In accordance with Executive Order 13272, we have thoroughly 
reviewed this proposed rule to assess and take appropriate account of 
its potential impact on small businesses, small governmental 
jurisdictions, and small organizations. As discussed in section VIII.C. 
above and in chapter V of the PREA, MSHA has determined and certified 
that this proposed rule would not have a significant economic impact on 
a substantial number of small entities.

IX. Copy of the OSHA Reference Method (ORM)

    MSHA's existing asbestos standards require that the analyst 
determine fiber concentrations using a phase contrast microscopy 
analytical method with 400-450X magnification and count fibers 5 [mu]m 
or longer having a length to diameter aspect ratio of at least 3:1. The 
OSHA Reference Method contains these requirements.

29 CFR 1910.1001 Appendix A: OSHA Reference Method--Mandatory

    This mandatory appendix specifies the procedure for analyzing 
air samples for asbestos and specifies quality control procedures 
that must be implemented by laboratories performing the analysis. 
The sampling and analytical methods described below represent the 
elements of the available monitoring methods (such as Appendix B of 
their regulation, the most current version of the OSHA method ID-
160, or the most current version of the NIOSH Method 7400). All 
employers who are required to conduct air monitoring under paragraph 
(d) of the [OSHA] standard are required to utilize analytical 
laboratories that use this procedure, or an equivalent method, for 
collecting and analyzing samples.

Sampling and Analytical Procedure

    1. The sampling medium for air samples shall be mixed cellulose 
ester filter membranes. These shall be designated by the 
manufacturer as suitable for asbestos counting. See below for 
rejection of blanks.
    2. The preferred collection device shall be the 25-mm diameter 
cassette with an open-faced 50-mm electrically conductive extension 
cowl. The 37-mm cassette may be used if necessary but only if 
written justification for the need to use the 37-mm filter cassette 
accompanies the sample results in the employee's exposure monitoring 
record. Do not reuse or reload cassettes for asbestos sample 
    3. An air flow rate between 0.5 liter/min and 2.5 liters/min 
shall be selected for the 25-mm cassette. If the 37-mm cassette is 
used, an air flow rate between 1 liter/min and 2.5 liters/min shall 
be selected.
    4. Where possible, a sufficient air volume for each air sample 
shall be collected to yield between 100 and 1,300 fibers per square 
millimeter on the membrane filter. If a filter darkens in appearance 
or if loose dust is seen on the filter, a second sample shall be 
    5. Ship the samples in a rigid container with sufficient packing 
material to prevent dislodging the collected fibers. Packing 
material that has a high electrostatic charge on its surface (e.g., 
expanded polystyrene) cannot be used because such material can cause 
loss of fibers to the sides of the cassette.
    6. Calibrate each personal sampling pump before and after use 
with a representative filter cassette installed between the pump and 
the calibration devices.
    7. Personal samples shall be taken in the ``breathing zone'' of 
the employee (i.e., attached to or near the collar or lapel near the 
worker's face).
    8. Fiber counts shall be made by positive phase contrast using a 
microscope with an 8 to 10 X eyepiece and a 40 to 45 X objective for 
a total magnification of approximately 400 X and a numerical 
aperture of 0.65 to 0.75. The microscope shall also be fitted with a 
green or blue filter.
    9. The microscope shall be fitted with a Walton-Beckett eyepiece 
graticule calibrated

[[Page 43984]]

for a field diameter of 100 micrometers (+/-2 micrometers).
    10. The phase-shift detection limit of the microscope shall be 
about 3 degrees measured using the HSE phase shift test slide as 
outlined below.
    a. Place the test slide on the microscope stage and center it 
under the phase objective.
    b. Bring the blocks of grooved lines into focus.

    Note: The slide consists of seven sets of grooved lines (ca. 20 
grooves to each block) in descending order of visibility from sets 1 
to 7, seven being the least visible. The requirements for asbestos 
counting are that the microscope optics must resolve the grooved 
lines in set 3 completely, although they may appear somewhat faint, 
and that the grooved lines in sets 6 and 7 must be invisible. Sets 4 
and 5 must be at least partially visible but may vary slightly in 
visibility between microscopes. A microscope that fails to meet 
these requirements has either too low or too high a resolution to be 
used for asbestos counting.

    c. If the image deteriorates, clean and adjust the microscope 
optics. If the problem persists, consult the microscope 
    11. Each set of samples taken will include 10 percent blanks or 
a minimum of 2 field blanks. These blanks must come from the same 
lot as the filters used for sample collection. The field blank 
results shall be averaged and subtracted from the analytical results 
before reporting. A set consists of any sample or group of samples 
for which an evaluation for this standard must be made. Any samples 
represented by a field blank having a fiber count in excess of the 
detection limit of the method being used shall be rejected.
    12. The samples shall be mounted by the acetone/triacetin method 
or a method with an equivalent index of refraction and similar 
    13. Observe the following counting rules.
    a. Count only fibers equal to or longer than 5 micrometers. 
Measure the length of curved fibers along the curve.
    b. In the absence of other information, count all particles as 
asbestos that have a length-to-width ratio (aspect ratio) of 3:1 or 
    c. Fibers lying entirely within the boundary of the Walton-
Beckett graticule field shall receive a count of 1. Fibers crossing 
the boundary once, having one end within the circle, shall receive 
the count of one half (\1/2\). Do not count any fiber that crosses 
the graticule boundary more than once. Reject and do not count any 
other fibers even though they may be visible outside the graticule 
    d. Count bundles of fibers as one fiber unless individual fibers 
can be identified by observing both ends of an individual fiber.
    e. Count enough graticule fields to yield 100 fibers. Count a 
minimum of 20 fields; stop counting at 100 fields regardless of 
fiber count.
    14. Blind recounts shall be conducted at the rate of 10 percent.

Quality Control Procedures

    1. Intralaboratory program. Each laboratory and/or each company 
with more than one microscopist counting slides shall establish a 
statistically designed quality assurance program involving blind 
recounts and comparisons between microscopists to monitor the 
variability of counting by each microscopist and between 
microscopists. In a company with more than one laboratory, the 
program shall include all laboratories and shall also evaluate the 
laboratory-to-laboratory variability.
    2.a. Interlaboratory program. Each laboratory analyzing asbestos 
samples for compliance determination shall implement an 
interlaboratory quality assurance program that as a minimum includes 
participation of at least two other independent laboratories. Each 
laboratory shall participate in round robin testing at least once 
every 6 months with at least all the other laboratories in its 
interlaboratory quality assurance group. Each laboratory shall 
submit slides typical of its own work load for use in this program. 
The round robin shall be designed and results analyzed using 
appropriate statistical methodology.
    2.b. All laboratories should also participate in a national 
sample testing scheme such as the Proficiency Analytical Testing 
Program (PAT), or the Asbestos Registry sponsored by the American 
Industrial Hygiene Association (AIHA).
    3. All individuals performing asbestos analysis must have taken 
the NIOSH course for sampling and evaluating airborne asbestos dust 
or an equivalent course.
    4. When the use of different microscopes contributes to 
differences between counters and laboratories, the effect of the 
different microscope shall be evaluated and the microscope shall be 
replaced, as necessary.
    5. Current results of these quality assurance programs shall be 
posted in each laboratory to keep the microscopists informed.
    [57 FR 24330, June 8, 1992; 59 FR 40964, Aug. 10, 1994]

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List of Subjects

30 CFR Parts 56 and 57

    Air quality, Asbestos, Chemicals, Hazardous substances, Metals, 
Mine safety and health.

30 CFR Part 71

    Air quality, Asbestos, Chemicals, Coal mining, Hazardous 
substances, Mine safety and health.

    Dated: July 14, 2005.
David G. Dye,
Deputy Assistant Secretary of Labor for Mine Safety and Health.

    For the reasons set out in the preamble, and under the authority of 
the Federal Mine Safety and Health Act of 1977, we are proposing to 
amend chapter I of title 30 of the Code of Federal Regulations as 


    1. The authority citation for part 56 would continue to read as 

    Authority: 30 U.S.C. 811.

    2. Section 56.5001 would be amended by revising paragraph (b) to 
read as follows:

Sec.  56.5001  Exposure limits for airborne contaminants.

* * * * *
    (b) Asbestos standard. (1) Definitions. Asbestos is a generic term 
for a number of hydrated silicates that, when crushed or processed, 
separate into flexible fibers made up of fibrils. As used in this 
    Asbestos means chrysotile, amosite (cummingtonite-grunerite 
asbestos), crocidolite, anthophylite asbestos, tremolite asbestos, and 
actinolite asbestos.
    Fiber means a particulate form of asbestos 5 micrometers ([mu]m) or 
longer with a length-to-diameter ratio of at least 3-to-1.
    (2) Permissible Exposure Limits (PELs).
    (i) Full-shift exposure limit. A miner's personal exposure to 
asbestos shall not exceed an 8-hour time-weighted average, full-shift 
airborne concentration of 0.1 fibers per cubic centimeter of air (f/
    (ii) Excursion limit. No miner shall be exposed at any time to 
airborne concentrations of asbestos in excess of 1.0 fiber per cubic 
centimeter of air (f/cc) as averaged over a sampling period of 30 
    (3) Measurement of airborne fiber concentration. Fiber 
concentration shall be determined by phase contrast microscopy using a 
method statistically equivalent to the OSHA Reference Method in OSHA's 
asbestos standard found in 29 CFR 1910.1001, appendix A.
* * * * *


    3. The authority citation for part 57 would continue to read as 

    Authority: 30 U.S.C. 811.

    4. Section 57.5001 would be amended by revising paragraph (b) to 
read as follows:

Sec.  57.5001  Exposure limits for airborne contaminants.

* * * * *
    (b) Asbestos standard. (1) Definitions. Asbestos is a generic term 
for a number of hydrated silicates that, when crushed or processed, 
separate into flexible fibers made up of fibrils. As used in this 
    Asbestos means chrysotile, amosite (cummingtonite-grunerite 
asbestos), crocidolite, anthophylite asbestos, tremolite asbestos, and 
actinolite asbestos.
    Fiber means a particulate form of asbestos 5 micrometers ([mu]m) or 
longer with a length-to-diameter ratio of at least 3-to-1.
    (2) Permissible Exposure Limits (PELs).
    (i) Full-shift exposure limit. A miner's personal exposure to 
asbestos shall not exceed an 8-hour time-weighted average, full-shift 
airborne concentration of 0.1 fibers per cubic centimeter of air (f/
    (ii) Excursion limit. No miner shall be exposed at any time to 
airborne concentrations of asbestos in excess of 1.0 fiber per cubic 
centimeter of air (f/cc) as averaged over a sampling period of 30 
    (3) Measurement of airborne fiber concentration. Fiber 
concentration shall be determined by phase contrast microscopy using a 
method statistically equivalent to the OSHA Reference Method in OSHA's 
asbestos standard found in 29 CFR 1910.1001, appendix A.
* * * * *


    5. The authority citation for part 71 would be revised to read as 

    Authority: 30 U.S.C. 811, 951, 957.

    6. Section 71.701 would be amended by revising paragraphs (c) and 
(d) to read as follows:

Sec.  71.701  Sampling; general requirements.

* * * * *
    (c) Where concentrations of airborne contaminants in excess of the 
applicable threshold limit values, permissible exposure limits, or 
permissible excursions are known by the operator to exist in a surface 
installation or at a surface worksite, the operator shall immediately 
provide necessary control measures to assure compliance with Sec.  
71.700 or Sec.  71.702, as applicable.
    (d) Where the operator has reasonable grounds to believe that 
concentrations of airborne contaminants in excess of the applicable 
threshold limit values, permissible exposure limits, or permissible 
excursions exist, or are likely to exist, the operator shall promptly 
conduct appropriate air sampling tests to determine the concentration 
of any airborne contaminant which may be present and immediately 
provide the necessary control measures to assure compliance with Sec.  
71.700 or Sec.  71.702, as applicable.
    7. Section 71.702 would be revised to read as follows:

Sec.  71.702  Asbestos standard.

    (a) Definitions. Asbestos is a generic term for a number of 
hydrated silicates that, when crushed or processed, separate into 
flexible fibers made up of fibrils. As used in this part--
    Asbestos means chrysotile, amosite (cummingtonite-grunerite 
asbestos), crocidolite, anthophylite asbestos, tremolite asbestos, and 
actinolite asbestos.
    Fiber means a particulate form of asbestos 5 micrometers ([mu]m) or 
longer with a length-to-diameter ratio of at least 3-to-1.

[[Page 43989]]

    (b) Permissible Exposure Limits (PELs). (1) Full-shift exposure 
limit. A miner's personal exposure to asbestos shall not exceed an 8-
hour time-weighted average, full-shift airborne concentration of 0.1 
fibers per cubic centimeter of air (f/cc).
    (2) Excursion limit. No miner shall be exposed at any time to 
airborne concentrations of asbestos in excess of 1.0 fiber per cubic 
centimeter of air (f/cc) as averaged over a sampling period of 30 
    (c) Measurement of airborne fiber concentration. Fiber 
concentration shall be determined by phase contrast microscopy using a 
method statistically equivalent to the OSHA Reference Method in OSHA's 
asbestos standard found in 29 CFR 1910.1001, appendix A.

[FR Doc. 05-14510 Filed 7-28-05; 8:45 am]