EPA publishes final revision to Risk Determination for methylene chloride

The Environmental Protection Agency (EPA) announced the final revision to the Risk Determination for methylene chloride as a whole chemical substance under the Toxic Substances Control Act (TSCA). This revised Risk Determination concludes that methylene chloride presents an unreasonable risk of injury to health and supersedes the previous condition of use-specific no unreasonable risk determinations in the 2020 methylene chloride Risk Evaluation. EPA will next propose regulations to address unreasonable risks methylene chloride poses to human health and the environment.


What is methylene chloride and how is it regulated?

  • According to the EPA’s “ Use and Market Profile for Methylene Chloride,” methylene chloride (CAS RN 75-09-2), which is also called dichloromethane, is a volatile chemical used as a solvent in a variety of industries and applications, such as adhesives, paint and coating products, metal cleaning, chemical processing, and aerosols. In addition, it is used as a propellent, processing aid, or functional fluid in the manufacturing of other chemicals.
  • Methylene chloride (MC) has also been used as an extraction solvent for spice oleoresins and hops, as a postharvest fumigant for grains and strawberries, and as a degreening agent for citrus fruits. MC is no longer an active ingredient in any registered pesticide products, according to the National Library of Medicine’s Hazardous Substance Data Bank.
  • The EPA issued a final rule on March 27, 2019 prohibiting the manufacture (including import), processing, and distribution of methylene chloride for consumer paint and coating removal for consumer use. This action was taken due to acute human lethality resulting from exposure to MC. This final rule also requires manufacturers (including importers), processors, and distributors, except for retailers, of methylene chloride for any use to provide downstream notification of the prohibitions throughout the supply chain. It also requires limited recordkeeping.
  • This final rule states that methylene chloride is acutely lethal, a neurotoxicant, and a likely human carcinogen with the risk assessment presenting a detailed description of the range of adverse acute and chronic health effects associated with MC.

Regulation of methylene chloride under TSCA

  • On June 22, 2016, the “ Frank R. Lautenberg Chemical Safety for the 21st Century Act” was signed into law, amending the 1976 Toxics Substances Control Act. TSCA (section 6(b)), administered by EPA’s Office of Pollution Prevention and Toxics (OPPT), required EPA to initiate Risk Evaluations for 10 chemical substances drawn from the 2014 update of the TSCA Work Plan for Chemical Assessments. Going forward, TSCA imposed additional statutory requirements to ensure that Risk Evaluations and potential risk management rules continue on a rolling basis as the Risk Evaluations are completed.
  • The Risk Evaluation process is the second step, following Prioritization and before Risk Management, in EPA’s existing chemical process under TSCA. The Risk Evaluation determines whether a chemical substance presents an unreasonable risk to health or the environment, under the conditions of use, including an unreasonable risk to a relevant potentially exposed or susceptible subpopulation (PESS). TSCA Section 3(12) defines “potentially exposed or susceptible subpopulation as a group of individuals within the general population identified by the Administrator who, due to either greater susceptibility or greater exposure, may be at greater risk than the general population of adverse health effects from exposure to a chemical substance or mixture, such as infants, children, pregnant women, workers, or the elderly.”
  • EPA evaluates hazard and exposure, using scientific information and approaches in a manner that is consistent with the requirements of TSCA for the best available science, and ensures decisions are based on the weight-of-scientific-evidence approach (excluding consideration of costs or other non-risk factors). In accordance with TSCA Section 6(b), if the EPA finds unreasonable risk under the conditions of use in any final Risk Evaluation, the EPA will address the risks by proposing actions within the required timeframe.

2020 Risk Evaluation for methylene chloride

  • According to the EPA’s 2020 Risk Evaluation for methylene chloride, exposure is associated with a variety of cancer (lung and liver) and non-cancer adverse effects (neurotoxicity). “Acute exposure to methylene chloride is associated with adverse nervous system effects, such as decreased visual, auditory, and motor functions. Animals chronically exposed to methylene chloride experience liver, kidney, and cardiovascular system damage. EPA classifies methylene chloride as a probable carcinogen.”
  • EPA determined that the following six conditions of use of methylene chloride do not present an unreasonable risk of injury to health or the environment: manufacturing (domestic), processing as a reactant, processing (recycling), distribution in commerce, industrial and commercial use as a laboratory chemical, and disposal.
  • EPA determined 47 uses within the following categories of conditions of use present an unreasonable risk of injury to health: import, processing, industrial and commercial use as a solvent in adhesives, in paint and coating removers, in metal (non)aerosol degreasers, in finishing products, in automotive products, in apparel and footwear, in spot removers, in liquid lubricants; and numerous consumer uses.
  • The exposure pathways that were or could be regulated under another EPA-administered statute were excluded from the June 2020 methylene chloride Risk Evaluation. The excluded exposure pathways that were not assessed for human health are surface water, drinking water, and ambient air pathways. EPA is conducting a screening level approach to assess potential risks from the air and water pathways for several of the first 10 chemicals, including methylene chloride in order to determine if there are any unaccounted risks for MC. In the meantime, EPA is not incorporating the screening level approach into this risk evaluation.

2022 revised Risk Determination

  • The EPA announced on November 10, 2022 the final revision to the Risk Determination for methylene chloride under TSCA. The 2022 final Risk Determination revises and replaces Section 5 of the June 2020 Risk Evaluation where the findings of unreasonable risk to health were previously made for the individual conditions of use.
  • EPA revised the Risk Determination for methylene chloride in conformance with Executive Order 13990 of January 20, 2021, Protecting Public Health and the Environment and Restoring Science to Tackle the Climate Crisis (86 FR 7037) to better align with TSCA’s objective of protecting health and the environment.
  • This final revised Risk Determination was also decided in conformance with the path forward for TSCA chemical Risk Evaluations laid out by the EPA in June 2021. The “path forward” expands the review of the first 10 chemicals to undergo Risk Evaluations to include the consideration of exposure pathways to air, water, and disposal to the general population, taking into account fenceline communities.
  • The path forward also does not assume workers will have access to or wear personal protective equipment (PPE). Consequently, EPA is revising the assumption for methylene chloride that workers always and properly use PPE. For the June 2020 Risk Evaluation, EPA assumed that workers use PPE, specifically, respirators with an assigned protection factor ranging from 25 to 50 for 26 occupational conditions of use, and gloves with a protection factor of 10 or 20 for 39 occupational conditions of use.
  • For this final Risk Determination for MC, the EPA has evaluated the levels of risk present in baseline scenarios where PPE is not assumed to be used by workers. This approach of not assuming PPE use by workers considers the risk to potentially exposed or susceptible subpopulations (PESS) of workers who may not be covered by OSHA standards, such as self-employed individuals and public sector workers who are not covered by a State Plan. State Plans are OSHA-approved workplace health and safety programs operated by individual states or territories.
  • Consequently, EPA is withdrawing the five conditions of use from the June 2020 Methylene Chloride Risk Evaluation (Section 5.4.1) previously determined not to present unreasonable risks. These include inhalation risk to workers for three conditions of use, an additional risk to workers for acute and chronic non-cancer dermal exposures, and for cancer from inhalation exposures. These five in addition to the original 47 drive the unreasonable Risk Determination for methylene chloride. This means 52 out of 53 conditions are unreasonable due to risks identified for human health. The one remaining condition of use that does not present an unreasonable risk is distribution.
  • The final revised Risk Determination finds that methylene chloride, as a whole chemical substance, presents an unreasonable risk of injury to health and the environment when evaluated under its conditions of use. The EPA makes a determination of unreasonable risk just once for the whole chemical when it is clear the majority of the conditions of use warrant one determination.
  • EPA explains that the revised determination does not change the previous risk findings of the 2020 Risk Evaluation but rather looks at the whole chemical, which will allow a broader use of TSCA for regulation of certain risks. These Risk Evaluations may be reviewed in the EPA’s 2022 Non-Technical Summary of Risk Evaluation for Methylene Chloride. A summary of the public and external peer review comments from the Science Advisory Committee on Chemicals (SACC) received by the EPA’s Office of Pollution Prevention and Toxics (OPPT) for the Risk Evaluation of methylene chloride may be reviewed here. The EPA also provides EPA/OPPT’s response to the comments received from the public and the peer review panel.
  • Consequently, EPA has made a revised determination of unreasonable risk as a two-pronged consideration for methylene chloride as a whole chemical substance instead of determining unreasonable risks based on each individual condition of use (COU); which does not reflect an assumption that workers always have or wear personal protective equipment (PPE) properly.

Comments on the Final Risk Determination for Methylene Chloride

  • On July 5, 2022, the EPA published a request for comments on a draft revision to the Risk Determination for Methylene Chloride. EPA received a total of 20 public submissions, of which 19 were unique and responsive to the request for comments. Commenters included environmental advocacy groups, NGOs, industry groups, companies, and individuals.
  • Several non-governmental and health advocacy organizations supported the whole chemical approach and the assumption of no PPE, as well as EPA’s new path forward for TSCA Risk Evaluations. Others conveyed general opposition to the final Risk Determination asserting it will have unwarranted impacts on future risk management decision-making and cause unintended regulatory impacts on articles (including replacement parts) containing certain substances.
  • Commenters in opposition to the whole chemical approach assert it is inconsistent with TSCA and the Risk Evaluation rule. EPA responded that TSCA requires scientific support for changes in approach and that this change is based on the peer reviewed risk characterization in the June 2020 Methylene Chloride Risk Evaluation. The risk characterization was based on reasonably available information (TSCA section 26(k)), the best available science, and based on the weight of scientific evidence (Section 6(h)).
  • In response to comments on conditions-of-use and EPA’s “whole chemical” approach, EPA explains that a use-by-use Risk Determination does not specifically infer that it is a required approach. EPA explains it decided on the unreasonable Risk Determination based on a passage in the final Risk Evaluation Rule which states, “the objective of conducting a technically sound, manageable evaluation [is] to determine whether a chemical substance—not just individual uses or activities—presents an unreasonable risk.” (82 FR at 33729).
  • The opposition to EPA’s intention not to assume PPE or other mitigation measures assert that OSHA requirements and industry best practices are being ignored and that those not following OSHA regulations should not govern the Risk Determination. EPA has stated that it considers “the risk to potentially exposed or susceptible subpopulations of workers who may not be covered by OSHA standards, such as self-employed individuals and public sector workers who are not covered by a State Plan.” However, EPA plans to “consider reasonably available information on use of PPE or other ways industry protects its workers, as a potential way to address unreasonable risk during the risk management process.”
  • A manufacturer of specialty batteries for “essential use” in military, space exploration, and medical uses commented that methylene chloride is the only substance known that enables the production of battery casings of sufficient strength and durability for use and that there are no technically and economically feasible safer alternatives to methylene chloride. The product manufacturer also stated that the risk of hazard and exposure is low for this use of MC and asserted this use meets a TSCA section 6(g) exemption because preventing this use would significantly disrupt national security.
  • EPA responded it will be considering this information in the development of the risk management rule and will evaluate the levels of risk present in scenarios considering applicable OSHA requirements, and industry best practices for industrial hygiene. EPA is encouraging specific comments about worker protection measures, engineering, and administrative controls in the comment period for the risk management rulemaking.
  • Similarly, an industry coalition commented that the use of MC as a feedstock in closed systems to produce fluorinated substances is different from direct applications of use as solvents and should be treated differently as MC is critical to compliance with the American Innovation and Manufacturing Act of 2020. EPA responded that it would consider this context during rulemaking.


Next Steps

  • EPA did not identify risks of injury to the environment that drive the unreasonable Risk Determination for methylene chloride. EPA has been conducting a screening level approach to assess potential risks from the air and water pathways for several of the first 10 chemicals, including MC. Since exposure pathways that were or could be regulated under another EPA administered statute were excluded from the final Risk Evaluation, surface water, drinking water and ambient air pathways were not assessed in the Risk Evaluation for MC. The goal of the recently developed screening approach is to remedy this exclusion and to identify if there may be risks that were unaccounted for in the methylene chloride Risk Evaluation. EPA expects to describe its views regarding the chemical-specific application of this screening-level approach in the forthcoming proposed rule for methylene chloride.
  • EPA will be initiating the process to address, by rule, the unreasonable risks identified in the Final Risk Determination for MC. It appears from EPA’s response to comments that it will take into consideration specific uses of MC and evidence of specific industry practice of the use of PPE for exposure to methylene chloride. The comment document responds to each and every commenter and leads one to believe that the Risk Management Rules could be more industry friendly.

To contact the author of this article, please email Patricia Iscaro ( [email protected])
To contact the editor of this article, please email Scott Stephens ( [email protected])

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