[Federal Register Volume 89, Number 181 (Wednesday, September 18, 2024)]
[Notices]
[Pages 76467-76469]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-21229]


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ENVIRONMENTAL PROTECTION AGENCY

[EPA-HQ-OPPT-2024-0425; FRL-12241-01-OCSPP]


1,3-Butadiene; Draft Risk Evaluation Under the Toxic Substances 
Control Act (TSCA); Science Advisory Committee on Chemicals (SACC) Peer 
Review; Request for Nominations of ad hoc Peer Reviewers

AGENCY: Environmental Protection Agency (EPA).

ACTION: Notice.

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SUMMARY: The Environmental Protection Agency (EPA or the Agency) is 
seeking nominations of scientific and technical experts that EPA can 
consider for service as ad hoc peer reviewers assisting the Science 
Advisory Committee on Chemicals (SACC) with the peer review of the 
draft risk evaluation for 1,3-butadiene conducted under the Toxic 
Substances Control Act (TSCA). To facilitate nominations, this document 
provides information about the SACC, the intended topic for the planned 
peer review, the expertise sought for this peer review, instructions 
for submitting nominations to EPA, and the Agency's plan for selecting 
the ad hoc peer reviewers for this peer review. EPA is planning to 
convene a virtual public meeting of the SACC in early 2025 to review 
the draft risk evaluation.

DATES: Submit your nominations on or before October 18, 2024.

ADDRESSES: Submit your nomination via email to [email protected] following 
the instructions in Unit III. Do not electronically submit any 
information you consider to be Confidential Business Information (CBI) 
or other information whose public disclosure is restricted by statute. 
If your nomination may contain any such information, please contact the 
Designated Federal Official to obtain special instructions before 
submitting that information.

FOR FURTHER INFORMATION CONTACT: The Designated Federal Official is 
Alie Muneer, Mission Support Division (7602M), Office of Program 
Support, Office of Chemical Safety and Pollution Prevention, 
Environmental Protection Agency; telephone number: (202) 564-6369 or 
call the main office at (202) 564-8450; email address: 
[email protected].

SUPPLEMENTARY INFORMATION:

I. General Information

A. What action is the Agency taking?

    The Agency is seeking public nominations of scientific and 
technical experts that EPA can consider for service as ad hoc peer 
reviewers for the SACC peer review of the draft risk evaluation for 
1,3-butadiene. EPA will be soliciting comments from the experts on the 
approach and methodologies utilized in the draft risk evaluation. This 
document provides instructions for submitting such nominations for EPA 
to consider for the SACC peer review. EPA will publish a separate 
document in the Federal Register in the fall of 2024 to announce the 
availability of the draft risk evaluation and solicit public comments. 
The public comments received during the public comment period for the 
draft risk evaluation material will be provided to the SACC and ad hoc 
peer reviewers.

B. What is the Agency's authority for taking this action?

    The SACC operates in accordance with TSCA section 26(o), 15 U.S.C. 
2625(o) and the Federal Advisory Committee Act (FACA), 5 U.S.C. 10, to 
provide independent advice and expert consultation with respect to the 
scientific and technical aspects of issues relating to the 
implementation of TSCA, 15 U.S.C. 2601 et seq., the Pollution 
Prevention Act (PPA), 42 U.S.C. 13101 et seq., and other applicable 
statutes.

C. Does this action apply to me?

    This action is directed to the public in general. This action may, 
however, be of interest to those involved in the manufacture, 
processing, distribution, and disposal of chemical substances and 
mixtures, and/or those interested in the assessment of risks involving 
chemical substances and mixtures regulated under TSCA. Since other 
entities may also be interested, the Agency has not attempted to 
describe all the specific

[[Page 76468]]

entities that may be affected by this action.

II. Background

A. What is the purpose of the SACC?

    The SACC provides independent advice and recommendations to the EPA 
on the scientific and technical aspects of risk assessments, 
methodologies, and pollution prevention measures and approaches for 
chemicals regulated under TSCA. The SACC is comprised of experts in 
toxicology; environmental risk assessment; exposure assessment; and 
related sciences (e.g., synthetic biology, pharmacology, biotechnology, 
nanotechnology, biochemistry, biostatistics, physiologically based 
pharmacokinetic (PBPK) modeling, computational toxicology, 
epidemiology, environmental fate, environmental engineering and 
sustainability). The SACC currently consists of 20 members. When 
needed, the committee will be assisted by ad hoc peer reviewers with 
specific expertise in the topics under consideration.

B. Why is EPA conducting these risk evaluations?

    TSCA requires EPA to conduct risk evaluations on prioritized 
chemical substances and identifies the minimum components EPA must 
include in all chemical substance risk evaluations. The purpose of 
conducting risk evaluations is to determine whether a chemical 
substance presents an unreasonable risk to human health or the 
environment under the Conditions of Use (COUs). These evaluations 
include assessing unreasonable risks to relevant potentially exposed or 
susceptible subpopulations. As part of this process EPA: (1) Integrates 
hazard and exposure assessments using the best available science that 
is reasonably available to assure decisions are based on the weight of 
the scientific evidence, and (2) Conducts peer review for risk 
evaluation approaches that have not been previously peer reviewed. For 
more information about the three stages of the TSCA risk evaluation 
process for existing chemicals (i.e., prioritization, risk evaluation, 
and risk management), go to https://www.epa.gov/assessing-and-managing-chemicals-under-tsca.

C. Why is EPA evaluating the risks from 1,3-butadiene?

    In December 2019, EPA designated 1,3-butadiene (CASRN 106-99-0) as 
a high-priority substance for risk evaluation following the 
prioritization process as required by Section 6(b) of TSCA and 
implementing regulations (40 CFR part 702) (Docket ID: EPA-HQ-OPPT-
2019-0131).
    1,3-Butadiene (CASRN 106-99-0) is a volatile, colorless gas with a 
total U.S. production volume between 1 and 5 billion pounds. It is 
produced in petrochemical processing and extracted and further 
processed as a building block for several polymers and elastomers that 
do not readily depolymerize. Air is expected to be the major pathway of 
exposure for 1,3-butadiene in the environment. Although 1,3-butadiene 
is moderately soluble in water, monitoring data indicate that it is not 
detected in water. Environmental release data show that more than 98 
percent of 1,3-butadiene facility releases are to air. Once in air, 
1,3-butadiene will not deposit to land or adsorb to organic matter. 
Long-range transport in air is not expected, in part, because 1,3-
butadiene has a short half-life (<8 hours) and will degrade into 
formaldehyde and acrolein.
    Reduced fetal body weight and hematological effects are indicated 
as the most sensitive and robust non-cancer human health hazards. EPA 
has previously classified 1,3-butadiene as a human carcinogen and 
epidemiology studies have demonstrated an association between 1,3-
butadiene exposure and increased incidence of leukemia in workers.
    EPA will be submitting the draft risk evaluation of 1,3-butadiene 
and associated supporting documents for external peer review. The draft 
risk evaluation will include analyses of physical-chemical properties, 
the fate and transport in the environment, releases to the environment, 
exposure to workers and the general population, including potentially 
exposed or susceptible subpopulations, environmental risk 
characterization, and human health hazard and risk characterization for 
workers and the general population.

D. What is the topic of the planned SACC peer review?

    EPA is focusing its charge to the SACC on methods and analyses that 
are novel and have not been reviewed in other venues. Methods and 
analyses used in this risk evaluation that are not novel, have been 
reviewed during development of the tools, used in previously reviewed 
agency work products, or used in previous TSCA assessments (e.g., 
systematic review, BMDS, etc.) are not included in the charge 
questions. Feedback from this review will be considered in the 
development of the final risk evaluation for 1,3-butadiene under TSCA. 
Specifically, EPA will be seeking comment on the issues below:
     No exposure to aquatic and terrestrial species is expected 
due to the physical and chemical properties of 1,3-butadiene, which is 
primarily released to air and does not partition, deposit, or persist 
in or on water or soil. Monitoring data indicate that 1,3-butadiene is 
not detected in water. Exposure of terrestrial organisms via ambient 
air will be brief due to the reactive nature of 1,3-butadiene. EPA will 
be seeking comment on the qualitative risk assessment for ecological 
taxa for 1,3-butadiene.
     1,3-Butadiene photodegrades with a half-life ranging from 
1.6-2.6 hours to form formaldehyde and acrolein when it reacts with 
hydroxyl radicals in the atmosphere. Because non-cancer health effects 
of formaldehyde and acrolein are dissimilar to 1,3-butadiene non-cancer 
health effects, risks will not be combined. EPA will be seeking comment 
on the preliminary decision not to combine risk from non-cancer health 
effects of 1,3-butadiene and its transformation products.
     Reduced fetal/neonatal body weight is observed in both 
mice and rats, though there is no evidence that this effect results 
from a single dose. No other candidate acute endpoints were identified. 
As such, EPA has not identified a relevant endpoint for acute, single-
day exposure to 1,3-butadiene. EPA will be seeking comment on this 
preliminary conclusion to forego establishing an acute point of 
departure.
     Ovarian atrophy is an adverse effect observed only in mice 
and can be attributed to a specific 1,3-butadiene metabolite 
(diepoxybutane) that is less prevalent in rats and humans. EPA is 
conducting an evaluation of the relevance of ovarian atrophy for 
assessing human risk. EPA will be proposing to use decreased fetal body 
weight as the basis for the intermediate and chronic points of 
departure for 1,3-butadiene. EPA will be seeking comment on these 
preliminary conclusions to establish intermediate and chronic points of 
departure based on reduced fetal body weight instead of ovarian 
atrophy.
     OPPT is revising the inhalation unit risk (IUR) for 1,3-
butadiene presented in the IRIS 2002 assessment to incorporate updated 
epidemiological cohort data. EPA will be seeking comment on the 
mathematical approach and new epidemiological cohort data used in the 
revised IUR.
     EPA is conducting a mutagenic mode of action analysis and 
evaluating whether the use of an age-dependent adjustment factor (ADAF) 
for leukemia is appropriate. EPA will be seeking

[[Page 76469]]

comment on this analysis and preliminary conclusion.
     The majority of occupational exposure sampling data 
points, collected from OSHA, NIOSH, and ACC's report, are not 
quantifiable values but are identified as being below the limit of 
detection (LOD). For datasets including exposure data that were 
reported as below the LOD, EPA is estimating exposure concentrations, 
following EPA's Guidelines for Statistical Analysis of Occupational 
Exposure Data. EPA will be seeking comment on this approach and the 
relevance of this dataset for risk characterization.
     General population exposure to 1,3-butadiene is being 
modeled using the Human Exposure Model (HEM) to estimate ambient air 
concentrations based on releases reported to the Toxic Release 
Inventory (TRI) for years 2016 to 2021. Exposure concentrations are 
being modeled at discrete distances from releasing facilities and 
surrounding census blocks. EPA will be seeking comment on this analysis 
and preliminary conclusions.
    EPA intends to publish a separate document in the Federal Register 
to announce the availability of and solicit public comment on the draft 
risk evaluation for 1,3-butadiene that will be submitted to the SACC 
for peer review, at which time EPA will provide instructions for 
submitting written comments and registering to provide oral comments at 
the peer review meeting with the SACC that is planned for early 2025.

III. Nominations of Ad Hoc Peer Reviewers

A. Why is EPA seeking nominations for ad hoc peer reviewers?

    EPA is requesting nominations from the public and stakeholder 
communities for scientific and technical experts who can serve as 
prospective candidates for ad hoc peer reviewers supporting the SACC. 
This is part of a broader process for developing a pool of candidates. 
Interested persons or organizations can nominate qualified individuals 
by following the instructions provided in this document. Individuals 
are also welcome to self-nominate.
    Those who are selected from the pool of prospective candidates will 
be invited to attend the public meeting and to participate in the 
discussion of key issues and assumptions at the meeting. In addition, 
they will be asked to review and help finalize the meeting minutes.

B. What expertise is sought for this SACC peer review?

    Individuals nominated for this ad hoc peer review should have 
expertise in one or more of the following areas:
    1. Risk assessment.
    2. Ecological risk assessment, specifically with expertise in 
physical chemistry, environmental fate, and synthetic polymers.
    3. Human health assessment, specifically with expertise in modes of 
action, mutagenicity, developmental and reproductive toxicity, dose-
response, and cancer epidemiology.
    4. Exposure assessment, specifically with expertise in occupational 
inhalation monitoring and air exposure modeling.
    Nominees should be scientists who have sufficient professional 
qualifications, including training and experience, to be capable of 
providing expert comments on the scientific issues for this review.

C. How do I make a nomination?

    By the deadline indicated under DATES, submit your nomination via 
email to the email identified in ADDRESSES. Each nomination should 
include the following: Contact information for the person or entity 
making the nomination; name, affiliation, and contact information for 
the nominee; and the disciplinary and specific areas of expertise of 
the nominee.

D. Will ad hoc peer reviewers be subjected to an ethics review?

    SACC members and ad hoc reviewers are subject to the provisions of 
the Standards of Ethical Conduct for Employees of the Executive Branch 
at 5 CFR part 2635, conflict of interest statutes in Title 18 of the 
United States Code and related regulations. In anticipation of this 
requirement, prospective candidates for service on the SACC as ad hoc 
peer reviewers will be asked to submit confidential financial 
information which shall fully disclose, among other financial 
interests, the candidate's employment, stocks and bonds, and where 
applicable, sources of research support. EPA will evaluate the 
candidates' financial disclosure forms to assess whether there are 
financial conflicts of interest, appearance of a loss of impartiality, 
or any prior involvement with the development of the documents under 
consideration (including previous scientific peer review) before the 
candidate is considered further for service.

E. How will EPA select the ad hoc peer reviewers?

    The selection of scientists to serve as ad hoc peer reviewers for 
the SACC is based on the function of the Committee and the expertise 
needed to address the Agency's charge to the Committee. No interested 
scientists shall be ineligible to serve by reason of their membership 
on any advisory committee to a federal department or agency or their 
employment by a federal department or agency, except EPA. Other factors 
considered during the selection process include availability of the 
prospective candidate to fully participate in the Committee's reviews, 
ability to be hired as an EPA Special Government Employee (SGE), 
absence of any conflicts of interest or appearance of loss of 
impartiality, independence with respect to the matters under review, 
and lack of bias. Although financial conflicts of interest, the 
appearance of loss of impartiality, lack of independence, and bias may 
result in non-selection, the absence of such concerns does not assure 
that a candidate will be selected to serve on the SACC.
    Numerous qualified candidates are often identified for SACC 
reviews. Therefore, selection decisions involve carefully weighing a 
number of factors including the candidates' areas of expertise and 
professional qualifications and achieving an overall balance of 
different scientific perspectives across peer reviewers. The Agency 
will consider all nominations of prospective candidates for service as 
peer reviewers that are received on or before the date listed in the 
DATES section of this document. However, the final selection of peer 
reviewers is a discretionary function of the Agency. At this time, EPA 
anticipates selecting approximately 8-10 ad hoc peer reviewers for this 
SACC peer review.
    EPA plans to make a list of candidates under consideration as 
prospective peer reviewers for this SACC review available for public 
comment during the fall of 2024. The list will be available in the 
docket at https://www.regulations.gov (docket ID number EPA-HQ-OPPT-
0425) and through the SACC website at https://www.epa.gov/tsca-peer-review.

    Dated: September 12, 2024.
Michal Freedhoff,
Assistant Administrator, Office of Chemical Safety and Pollution 
Prevention.
[FR Doc. 2024-21229 Filed 9-17-24; 8:45 am]
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