Background on Risk Evaluation Under the Toxic Substances Control Act (TSCA): 1-Bromopropane
INSIGHTi
Background on Risk Evaluation Under the
Toxic Substances Control Act (TSCA): 1-
Bromopropane
September 12, 2022
In 2016, the Frank R. Lautenberg Chemical Safety for the 21st Century Act (LCSA; P.L. 114-182)
amended Title I of the Toxic Substances Control Act (TSCA; 15 U.S.C. §2601 et seq.) to direct the U.S.
Environmental Protection Agency (EPA) to systematically prioritize chemicals for risk evaluation. (For
more information, see CRS Report R45149, Title I of the Toxic Substances Control Act (TSCA): A
Summary of the Statute.) The purpose of the risk evaluations is to determine whether particular chemicals
warrant regulation in terms of the risks associated with their manufacture, processing, distribution, use, or
disposal. If EPA identifies “unreasonable” risk to human health or the environment associated with one or
more of the elements of a chemical’s lifecycle, TSCA Section 6 directs EPA to promulgate a rule to
mitigate those risks. TSCA Section 9 limits EPA’s authority to regulate a chemical under TSCA if another
law may be used to regulate a chemical for the unreasonable risk identified by the agency.
As amended, TSCA Section 6 directed EPA to select 10 chemicals for risk evaluation from a list of 90
chemicals that the agency identified in 2014 as warranting risk assessment. EPA based this list on a
screening of 345 chemicals for potential hazard and exposure, and persistence and bioaccumulation
characteristics. With more than 86,000 chemicals on the TSCA Inventory, EPA’s screening approach was
intended to focus the agency’s resources and attention on a select group of chemicals for which sufficient
scientific and technical information is available to suggest greater concern to human health or the
environment. Pursuant to TSCA Section 6, EPA selected the initial 10 chemicals for risk evaluation,
including 1-bromopropane (1-BP), in 2016 (81 Federal Register 91927-91929, December 19, 2016).
Each chemical substance that EPA evaluates has unique properties, uses, and risks, which may warrant
different risk management approaches. The process of conducting risk evaluations and assessing risk
management options involves judgments about the reliability of available scientific and technical
information. Aspects of this process and what information EPA identifies as the basis for justifying certain
regulatory action can generate disagreement between the agency and stakeholders (e.g., industry,
environmental and public health organizations). As EPA continues to implement TSCA, the agency’s risk
evaluations and related actions are likely to receive scrutiny among stakeholders. Congress may consider
assessing EPA’s implementation of TSCA, as amended by the LCSA, and the resulting outcomes from the
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agency’s actions and decisions. The next section discusses EPA’s risk evaluation for 1-BP and potential
next steps toward addressing the unreasonable risks that the agency identified.
1-Bromopropane (1-BP)
In 2016, EPA selected 1-BP (CAS Number 106-94-5) as one of the initial 10 chemicals for which a risk
evaluation would be conducted. 1-BP is predominantly used as a solvent for a variety of industrial and
commercial applications. According to EPA, approximately 26 million pounds of 1-BP are manufactured
in, or imported to, the United States annually.
In August 2020, EPA finalized its risk evaluation for 1-BP, identifying unreasonable risks to the health of
workers, occupational non-users, consumers, and bystanders from 16 out of 25 conditions of use
described and evaluated by the agency. EPA did not identify unreasonable risks to the general population
and environment from the evaluated conditions of uses. EPA based its risk determinations on a
comparison of various sources of scientific information. The agency considered the predicted exposure to
1-BP from various exposure scenarios (e.g., workers involved in handling the chemical with or without
the use of a respirator) and an estimated level of exposure expected not to result in adverse health effects
while taking into account a margin of exposure. Additionally, EPA compared predicted exposure to 1-BP
with an estimated level of exposure associated with certain guideline limits to the risk of developing lung
cancer. EPA primarily relied on findings from rodent studies to inform its evaluation. EPA’s risk
determinations regarding potential environmental effects are based on the predicted exposure to 1-BP for
various species compared to the estimated level of exposure expected not to result in the development of
adverse effects in species at the population level.
In June 2021, EPA announced its intention to approach the TSCA unreasonable risk determinations by
making one determination for a chemical substance rather than multiple determinations for each condition
of use. In July 2022, EPA released a draft revised risk determination for 1-BP, which indicates that the
chemical presents unreasonable risks to human health. This revised risk determination would supersede
the August 2020 risk determinations in the risk evaluation.
Given that EPA identified unreasonable risks associated with 1-BP, the agency is developing a rule under
TSCA Section 6 to address such risks and anticipates proposing this rule in October 2022. Section 6(a)
identifies seven risk management options that EPA may use alone or in combination to address the risks
of 1-BP, including prohibiting the manufacture of the chemical and requiring manufacturers of the
chemical to communicate the chemical’s risks to allow downstream processors, users, and distributors the
opportunity to take applicable protective measures. In developing the rule, EPA is required pursuant to
Section 6 to identify various risk management options that would adequately address the identified
unreasonable risk and determine the associated costs for each proposed risk management option. The
forthcoming risk management rule could supplement existing regulations that apply to 1-BP.
Relatedly, in February 2022, EPA added 1-BP to the list of hazardous air pollutants subject to stationary
source emissions standards promulgated under Section 112 of the Clean Air Act (42 U.S.C. §7412). See
87 Federal Register 393-396, January 5, 2022. The extent to which EPA addresses risks to human health
and the environment associated with 1-BP using TSCA or other statutes the agency administers may be an
issue that Congress considers in evaluating whether implementation of TSCA is aligned with the intent of
the TSCA amendments.
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Author Information
Jerry H. Yen
Analyst in Environmental Policy
Disclaimer
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