[Federal Register Volume 61, Number 16 (Wednesday, January 24, 1996)]
[Notices]
[Pages 1947-1950]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-952]
-----------------------------------------------------------------------
DEPARTMENT OF LABOR
Occupational Safety and Health Administration
Updating Permissible Exposure Limits (PELS) for Air Contaminants;
Meeting
AGENCY: The Occupational Safety and Health Administration, Labor.
ACTION: Notice of Public Meeting on Updating Permissible Exposure
Limits (PELs) for Air Contaminants.
-----------------------------------------------------------------------
[[Page 1948]]
DATE AND TIME: Thursday, February 22, 1996; 9 a.m. to 5 p.m.
PLACE: Frances Perkins Building, Auditorium, 200 Constitution Ave., NW,
Washington, DC 20210. Metro, Judiciary Square Station on the Red Line.
PUBLIC PARTICIPATION: The meeting is open to the public. The room
accommodates approximately 240 persons. Pre-registration requested for
all participants and required for those planning on making a brief
presentation. To register, please send the following information by
mail or fax to Julia Pesak at: US Department of Labor/OSHA, Rm. N 3718,
200 Constitution Ave., NW., Washington, DC 20210 Fax: (202) 219-7125
Or, to register by e-mail, send the same information to Lyn
Penniman at: [email protected]
Information required to register: Name of participant, Organization
represented by participant, Topic(s) participant desires to address,
Approximate time requested for each topic, maximum of 15 minutes total
for each participant.
Registration deadline: Received by Monday, February 12, 1996.
Registration confirmation: OSHA will confirm all registrations
received by the deadline. OSHA will chair the meeting and allot time to
cover the agenda and permit differing viewpoints to be aired.
AGENDA FOR PUBLIC MEETING: The first portion of the public meeting will
include background information on OSHAs past effort and current
strategy for updating Permissible Exposure Limits (PELs), followed by a
general discussion of OSHAs method for identifying substances for
inclusion in the current phase of rulemaking. The second portion will
cover significance of risk, risk assessment methodology as applied to
both carcinogenic and noncarcinogenic end points, and feasibility
analysis methodology.
FOR FURTHER INFORMATION: Call Phyllis Yates or Julia Pesak at (202)
219-7111. Please note that registrations will not be accepted by
telephone.
SUPPLEMENTARY INFORMATION:
Background
When the Occupational Safety and Health Administration was
established in 1971, the Agency was given two years to adopt existing
federal and national consensus standards. Among other standards, OSHA
adopted Threshold Limit Values (TLVs) from the American Conference of
Governmental Industrial Hygienists (ACGIH), which in turn had become
federal standards under the Walsh-Healy Act. These limits, in addition
to exposure limits from the American National Standards Institute
(ANSI), were codified in the Code of Federal Regulations (CFR) as
Permissible Exposure Limits (PELs) in Sec. 1910.1000, Subpart Z.
Subpart Z became known as OSHAs Z-Tables, and were enforced by OSHA to
protect the health of workers from adverse health effects associated
with overexposure to air contaminants in general industry. Minor
differences in regulatory history resulted in slightly different limits
for the construction and maritime industries.
In the 1980s, it became widely recognized that many of the limits
in OSHAs Z-Tables were outdated, and in 1988 OSHA proposed to update
approximately 420 of its PELs in its air contaminants rulemaking. The
newer PELs were based on more recent scientific information, and that
information indicated that all but one of the new PELs needed to be
more protective of worker health than were the old limits. OSHA
utilized in part the recommendations made by the ACGIH and the National
Institute of Occupational Safety and Health (NIOSH) in an effort to
streamline the process. Following hearings and written comments OSHA
published its final rule on January 19, 1989 (54 FR 2332), reducing 212
PELs, setting 164 PELs for previously unregulated substances, and
raising one PEL. OSHA proposed to expand coverage of that rule to the
construction and maritime industries on June 12, 1992 (57 FR 26002).
Legal challenges to the standard by industry and labor groups were
consolidated and heard in the Eleventh Circuit Court of Appeals. In
July of 1992 the Court issued its decision (American Federation of
Labor and Congress of Industrial Organizations v. Occupational Safety
and Health Administration, 965 F. 2d 962). It stated, in essence, that
OSHA should perform quantitative analysis of risk for noncancer
endpoints where possible, that more extensive discussions of the health
evidence for each substance was needed, and that feasibility analysis
should be more detailed. Though only some of the substances were
individually challenged, the entire revised air contaminants standard
was vacated and remanded back to the Agency. Consequently, the Agency
was obligated to revert back to enforcing the limits set in the early
1970s.
Purpose
Establishing an ongoing mechanism for updating its PELs continues
to be a high priority for the Agency. OSHA seeks comment on the current
phase of its plan to establish an ongoing, iterative process for
updating outmoded Permissible Exposure Limits (PELs). Future phases
will differ from the current phase and include a mechanism for
establishing PELs for appropriate new substances (not currently
regulated) under Sec. 1910.1000, subpart Z. This meeting will be the
second on the topic of PELs with interested stakeholders since the
standard was remanded in 1992.
The Agency intends to publish a proposal to update PELs for a group
of approximately 20 substances in the late spring of 1996. Subsequent
to the previous public meeting in July 1995, OSHA has further narrowed
its likely priority candidates for proposed PEL rulemaking. The
substances included below represent OSHA's current intentions regarding
the substances to be included in the air contaminants proposal. The
actual proposal, when published, may add or drop a small number of
substances.
The list of substances currently slated for rulemaking, along with
the agenda of the meeting (including a brief discussion of risk
assessment and significance of risk issues of interest to OSHA), are
provided here for the purpose of focusing and facilitating substantive
discussion during the public meeting for stakeholders. The purpose of
this meeting is to discuss those general issues which are germane to
the current air contaminants rulemaking. It is not OSHA's intent to
discuss health effects information and other issues relevant only to
specific substances at this particular meeting. The regulatory process
will provide ample opportunity for interested parties to submit oral
and written comments on specific substances.
Current Candidates for Proposed Air Contaminants Rulemaking:
Carbon disulfide
Carbon monoxide
Chloroform
Dimethyl sulfate
Epichlorohydrin
Ethylene dichloride
Glutaraldehyde
n-Hexane
2-Hexanone
Hydrazine
Hydrogen sulfide
Manganese & compounds
Mercury & compounds
Nitrogen dioxide
Perchloroethylene
Sulfur dioxide
Toluene
Toluene diisocyanate
Trimellitic anhydride
Vinyl bromide
[[Page 1949]]
Issue I: Priority-Setting for PEL Chemicals
OSHA requests comment on its selection of priority substances for
this first phase of updating PELs. In identifying the priority
substances, OSHA (with assistance from NIOSH) evaluated the following
criteria: The inherent toxicity of the substance; the number of workers
exposed to the substance (and in some cases, the amount of the
substance produced); uses of the substance and prevailing exposure
levels; the severity of the resulting adverse health effect(s); the
availability of information useful in quantitative risk assessment, and
the quality of those data; and the potential for risk reduction.
Administrative considerations and professional judgement were also
factored in to the decision-making process. OSHA feels that this
approach, a hybrid of quantitative and qualitative elements rather than
a strictly quantitative formula, was appropriate and rational. The
criteria used to identify these substances are similar to those used by
OSHA's Priority Planning Process Committee to identify the Agency's
priorities for regulatory and other actions.
Although these priority substances were identified on the basis of
objective criteria, it should not be concluded that these are the only
substances in OSHA's Z-Tables that require new PELs, nor that these are
necessarily the highest-risk substances. It is important for worker
protection that the Agency propose PELs for noncarcinogens as well as
carcinogens, and for substances which have health effects that
adversely impact workers' quality of life without necessarily affecting
mortality. And, while it is important to establish PELs for these
particular substances, it is of equal importance to the Agency to begin
to lay the groundwork for a regular and iterative process for updating
PELs for air contaminants.
Issue II: Risk Assessment Methodology for Carcinogens
OSHA has gained much experience in conducting quantitative risk
assessments for carcinogens from past rulemaking efforts. The
approaches most often employed by the Agency, which rely on use of the
multistage model with animal data and relative risk models with human
data to derive dose-response relationships, are well known in the
scientific community and have been routinely upheld by reviewing
courts. The Agency does not expect to depart significantly from its use
of these approaches to derive revised exposure limits for potential
carcinogens included in the present rulemaking effort. However, OSHA is
interested in hearing discussion on certain issues regarding the
details of dose-response modeling for carcinogens, in particular: (1)
The appropriateness of relying on maximum likelihood estimates, upper
confidence limits, or other summary statistics for carcinogenic potency
such as expected values (for example, see Hattis and Goble 1991) to
derive exposure limits; (2) approaches that can be taken to address the
issue of interindividual variation in response among humans; (3) the
use of various interspecies scaling factors when assessing risks from
bioassay data; and (4) criteria for evaluating the adequacy of data to
determine when it is appropriate to use pharmacokinetic analysis as
part of the risk assessment.
Issue III: Risk Assessment Methodology for Noncarcinogens
OSHA is currently exploring the use of techniques to quantify risks
of non-neoplastic health effects associated with occupational exposure
to hazardous materials. This effort is designed to address the Eleventh
Circuit Court decision. OSHA believes that, wherever data permit,
conducting quantitative risk assessments for noncancer health endpoints
provides the most direct route for establishing new or revised exposure
limits in a manner consistent with the Court decision.
A variety of methods for establishing exposure limits based on
noncancer health endpoints have been used by regulatory agencies and
scientific bodies. One of the most frequently employed methods involves
setting exposure limits by applying uncertainty factors to no-observed-
adverse-effect (NOAEL) or lowest-observed-adverse- effect (LOAEL)
levels reported in human and animal studies. OSHA relied on this
approach to a large extent in the 1989 Air Contaminants rulemaking.
Although this approach has been widely used in the past, its chief
disadvantage is that it provides little or no information on potential
risk levels that may be associated with varying magnitudes of exposure,
a limitation that was recognized by the Court.
One of the newer approaches being evaluated by OSHA to conduct
noncancer risk assessments is known as the ``benchmark dose'' method,
originally described by Crump (1984). This method is currently being
used by the Environmental Protection Agency (EPA) to establish
Reference Doses (RfDs) based on noncancer health effects, and its
application has been recently studied and described in detail by EPA's
Risk Assessment Forum (EPA, 1995). This approach uses formal modeling
techniques similar to those used in cancer risk assessment to develop
quantitative dose-response relationships based on either human or
animal studies. The models are subsequently used to estimate a
benchmark dose associated with a specified excess risk level that lies
on or just below the observed range of risks (usually 5 or 10 percent).
The EPA document discusses two approaches for deriving references doses
from benchmark doses: one employs a system of uncertainty factors to
account for individual variation in response, extrapolation from animal
to humans, and severity of the effect, while the other approach reduces
the benchmark dose by some adjustment factor representing the desired
reduction in the magnitude of the risk. Thus, the benchmark dose
approach differs from those used in cancer risk assessments in that the
models developed are not used to extrapolate risks at very low dose
levels. Use of the benchmark dose approach has at least two advantages
over the traditional NOAEL/LOAEL method: (1) Quantitative dose-response
information can be obtained, which should facilitate regulatory
decision making; and (2) the approach provides for greater regulatory
consistency between substances since decisions can be based on
comparable starting points, i.e., risk levels of 5 or 10 percent.
Thus, OSHA believes that the benchmark dose approach shows promise
as a consistent and defensible method by which the Agency can establish
reasonable exposure limits based on nonneoplastic health effects. As
such, OSHA wishes to hear considerable discussion on the experience of
those who are familiar with or who have used this method to evaluate
public health risks, and what alternative approaches can be utilized
that address issues raised by the Court ruling on the Air Contaminants
standard. In particular, OSHA is interested in hearing discussion on
how to best implement approaches to derive exposure limits from
benchmark dose values, and how these methods can be interpreted in
terms of the significance of the risk and the magnitude of risk
reduction achieved.
Issue IV: Determination of Significant Risk
For significant risk determinations for carcinogens, OSHA has
followed the Supreme Court guidance in the Benzene decision. The Court
stated: ``It is the Agencys responsibility to determine in the first
instance what it considers to be
[[Page 1950]]
a ``significant'' risk. Some risks are plainly acceptable and others
are plainly unacceptable. If, for example, the odds are one in a
billion that a person will die from cancer by taking a drink of
chlorinated water, the risk clearly could not be considered
significant. On the other hand, if the odds are one in a thousand that
regular inhalation of gasoline vapors that are 2% benzene will be fatal
a reasonable person might well consider the risk significant and take
the appropriate steps to decrease or eliminate it.'' (Industrial Union
Department, AFL-CIO v. American Petroleum Institute, 448 U.S. 601, 655.
(1980)). OSHA would welcome comments that would enable it to shed light
on the acceptability of risk levels within this million-fold range.
OSHA has had less experience in evaluating significant risk for the
broad range of other adverse health effects experienced by workers who
are exposed to hazardous levels of chemical substances. OSHA invites
discussion on appropriate risk levels for effects such as
neurotoxicity, reproductive effects, and organ toxicity that may
represent significant risks, and on appropriate criteria (such as
severity and reversibility of the effect) that should be considered to
determine when risks of a given magnitude represent a significant risk.
References
Crump, K.S. 1984. A new method for determining allowable daily
intakes. Fund. Appl. Toxicol. 4:854-871
Environmental Protection Agency. February 1995. The Use of the
Benchmark Dose Approach in Health Risk Assessment. Publication No.
EPA/630/R-94/007, Washington, DC.
Hattis, D. And Goble, R.L. 1991. Expected values for projected
cancer risks from putative genetically acting agents. Risk Analysis
11:359-363
Authority: This document was prepared under the direction of
Joseph A. Dear, Assistant Secretary of Labor for the Occupational
Safety and Health, 200 Constitution Ave. NW., Washington, DC 20210.
Signed at Washington, DC, this 19th day of January, 1996.
Joseph A. Dear,
Assistant Secretary of Labor.
[FR Doc. 96-952 Filed 1-23-96; 8:45 am]
BILLING CODE 4510-26-P