Background on Risk Evaluation Under the Toxic Substances Control Act (TSCA): Methylene Chloride

INSIGHTi

Background on Risk Evaluation Under the
Toxic Substances Control Act (TSCA):
Methylene Chloride
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 methylene chloride, 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 methylene chloride
and potential next steps toward addressing the unreasonable risks that the agency identified.
Methylene Chloride
In 2016, EPA selected methylene chloride (CAS Number 75-09-2; also known as dichloromethane) as one
of the initial 10 chemicals for a risk evaluation. Methylene chloride is predominantly used as a solvent.
According to EPA, approximately 260 million pounds of methylene chloride are manufactured in, or
imported to, the United States annually.
In June 2020, EPA finalized its risk evaluation for methylene chloride, identifying unreasonable risks to
the health of workers, occupational non-users, consumers, and bystanders from 47 out of 53 conditions of
use that the agency evaluated. EPA did not identify unreasonable risks to 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 methylene chloride
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 methylene chloride 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’s June 2020 risk evaluation was challenged in court. In July 2021, the Ninth Circuit Court of
Appeals granted EPA’s motion to remand the risk evaluation to the agency “for the limited purpose of
permitting the agency to reconsider the challenged no-unreasonable risk determinations.” In June 2022,
EPA released a draft revised risk determination for methylene chloride, proposing that methylene chloride
as a “whole substance” presents unreasonable risks to human health. The draft revised risk determination,
if finalized, would supersede the risk determinations in the June 2020 risk evaluation.
Given that EPA identified unreasonable risks associated with methylene chloride, the agency is
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 methylene chloride,
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.
In its risk evaluation, EPA acknowledged multiple existing regulations (e.g., occupational standards,
stationary source emissions standards, drinking water standards, consumer product regulations) that apply
to methylene chloride, which were promulgated under various statutes that EPA and other agencies
administer. In 2019, EPA promulgated a rule under TSCA to prohibit the manufacture, processing, and
distribution of methylene chloride in all paint removers for consumer use. See 84 Federal Register 11420-
11436, March 27, 2019, and 40 C.F.R. Part 751, Subpart B. A rule to address unreasonable risk that
methylene chloride poses could build upon EPA’s 2019 rule and other existing regulations.
Since methylene chloride is manufactured at relatively high volumes, EPA’s forthcoming risk
management rule and underlying risk evaluation will likely be scrutinized by stakeholders. Congress may
conduct oversight or consider legislation with regard to EPA’s efforts to manage risks associated with
methylene chloride 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
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