INSIGHTi

Background on Risk Evaluation Under the
Toxic Substances Control Act (TSCA): N-
Methylpyrrolidone
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 N-methylpyrrolidone (NMP), 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 NMP and potential
next steps toward addressing the unreasonable risks that the agency identified.
N-Methylpyrrolidone (NMP)
In 2016, EPA selected NMP (CAS Number 872-50-4) as one of the initial 10 chemicals for which a risk
evaluation would be conducted. According to EPA, approximately 160 million pounds of NMP are
manufactured in, or imported to, the United States annually. NMP is predominantly used as a solvent in
the manufacture of a variety of industrial and consumer products, including electronics, petroleum
products, pharmaceuticals, polymers, and other specialty chemicals.
In December 2020, EPA finalized its risk evaluation for NMP, identifying unreasonable risks to the health
of workers and consumers from 26 of 37 conditions of use evaluated. EPA did not identify unreasonable
risks to occupational non-users, bystanders, the general population, or the environment from any of the
conditions of use that the agency evaluated. EPA based its determinations on a comparison of various
sources of scientific information. The agency considered the predicted exposure to NMP 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 the development of adverse health
effects while taking into account a margin of exposure. EPA’s risk determinations regarding potential
environmental effects are based on the predicted exposure to NMP 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.
EPA determined that certain developmental effects are associated with acute exposure to NMP through
ingestion and certain reproductive effects are associated with chronic exposure to NMP through ingestion.
Both determinations were largely based on rodent studies.
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 NMP, which indicates that the
chemical presents unreasonable risks to human health. This revised risk determination would supersede
the December 2020 risk determinations in the risk evaluation.
Given that EPA identified unreasonable risks associated with NMP, the agency is in the process of
developing a rule under TSCA Section 6 to address such risks. Section 6(a) identifies seven risk
management options that EPA may use alone or in combination to address the risks of NMP, 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.
Since NMP is manufactured at relatively high volumes, those who manufacture and use NMP are likely to
scrutinize the forthcoming risk management rule and underlying risk evaluation. Congress may conduct
oversight or consider legislation with regard to EPA’s efforts to manage the risks associated with NMP
and whether such efforts are aligned with the intent of the TSCA amendments.

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Author Information

Jerry H. Yen

Analyst in Environmental Policy




Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan shared staff
to congressional committees and Members of Congress. It operates solely at the behest of and under the direction of
Congress. Information in a CRS Report should not be relied upon for purposes other than public understanding of
information that has been provided by CRS to Members of Congress in connection with CRS’s institutional role.
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