Background on Risk Evaluation Under the Toxic Substances Control Act (TSCA): Carbon Tetrachloride
INSIGHTi
Background on Risk Evaluation Under the
Toxic Substances Control Act (TSCA): Carbon
Tetrachloride
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 carbon tetrachloride, 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 carbon tetrachloride
and potential next steps toward addressing the unreasonable risks that the agency identified.
Carbon Tetrachloride
In 2016, EPA selected carbon tetrachloride (CAS Number 56-23-5) as one of the initial 10 chemicals for
which a risk evaluation would be conducted. For many decades, carbon tetrachloride was used as a
solvent. Because carbon tetrachloride was found to contribute to stratospheric ozone depletion, the
Montreal Protocol on Substances That Deplete the Ozone Layer as amended and Title VI of the Clean Air
Act (42 U.S.C. §7671 et seq.) established a process to phase out carbon tetrachloride production in the
United States for most nonfeedstock domestic uses by 1996. For the past few years, carbon tetrachloride
has been used predominantly to manufacture other chemicals, such as hydrochlorofluorocarbons
(HCFCs), hydrofluorocarbons (HFCs), and hydrofluoroolefins (HFOs). According to EPA, approximately
130 million pounds of carbon tetrachloride are manufactured in, or imported to, the United States
annually.
In November 2020, EPA finalized its risk evaluation for carbon tetrachloride, identifying unreasonable
risks to the health of workers and occupational non-users from 13 conditions of use out of 15 evaluated.
EPA did not identify unreasonable risks to consumers, bystanders, the general population, or the
environment from any of the conditions of use evaluated by the agency. EPA based its determinations on a
comparison of various sources of scientific information. The agency considered the predicted exposure to
carbon tetrachloride 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 to limit the increase in
risk of developing liver cancer to certain guideline ranges. EPA primarily relied on rodent studies to
ascertain the carcinogenicity of carbon tetrachloride from inhalation and dermal exposures. EPA’s risk
determinations regarding potential environmental effects are based on the predicted exposure to carbon
tetrachloride 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 August 2022, EPA released a draft revised risk determination for carbon tetrachloride, which
indicates that the chemical presents unreasonable risks to human health. This revised risk determination
would supersede the November 2020 risk determinations in the risk evaluation.
EPA is developing a rule under TSCA Section 6 to address unreasonable risks identified by the agency
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 carbon tetrachloride, including
prohibiting the manufacture of the chemical and requiring manufacturers of the chemical to communicate
the chemicals’ 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,
drinking water standards, consumer product regulations) that apply to carbon tetrachloride, which were
promulgated under various statutes that EPA and other agencies administer. A risk management rule could
supplement these existing regulations. Congress may consider conducting oversight or consider
legislation with regard to EPA’s efforts to manage risks associated with carbon tetrachloride and whether
such effects are aligned with the intent of the TSCA amendments.
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Author Information
Jerry H. Yen
Analyst in Environmental Policy
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