On October 29, 2019, the U.S. Environmental Protection Agency (EPA) published a Federal Register notice announcing the availability of the draft Toxic Substances Control Act (TSCA) risk evaluation for methylene chloride (MC). 84 Fed. Reg. 57866. As reported in our October 25, 2019, memorandum, EPA is submitting the same document to the TSCA Science Advisory Committee on Chemicals (SACC) for peer review. SACC will convene an in-person public meeting to consider and review the draft risk evaluation on December 3-4, 2019. Preceding the in-person meeting, there will be a preparatory virtual public meeting on November 12, 2019, for SACC to consider the scope and clarity of the draft charge questions for the peer review. Registration for the preparatory virtual meeting must be completed on or before November 12, 2019, to receive the webcast meeting link and audio teleconference information. Written comments for the preparatory virtual meeting and requests for time to present oral comments are due by 12:00 p.m. on November 8, 2019. Written comments on the draft risk evaluation that are submitted to EPA on or before November 26, 2019, will be provided to SACC for review and consideration before the December 3-4, 2019, meeting. Requests to present oral comments at the in-person meeting are due December 3, 2019. Comments on the draft risk evaluation are due December 30, 2019.

Background

TSCA Section 6, as amended by the Frank R. Lautenberg Chemical Safety for the 21st Century Act (Lautenberg Act), requires EPA to conduct risk evaluations to “determine whether a chemical substance presents an unreasonable risk of injury to health or the environment, without consideration of costs or other nonrisk factors, including an unreasonable risk to a potentially exposed or susceptible subpopulation identified as relevant to the risk evaluation by the Administrator, under the conditions of use.” The statute identifies the minimum components EPA must include in all risk evaluations. For each risk evaluation, EPA must publish a document that outlines the scope of the risk evaluation to be conducted, which includes the hazards, exposures, conditions of use, and the potentially exposed or susceptible subpopulations that EPA expects to consider. Each risk evaluation must also: (1) integrate and assess available information on hazards and exposure for the conditions of use of the chemical substance, including information on specific risks of injury to health or the environment and information on relevant potentially exposed or susceptible subpopulations; (2) describe whether aggregate or sentinel exposures were considered and the basis for that consideration; (3) take into account, where relevant, the likely duration, intensity, frequency, and number of exposures under the conditions of use; and (4) describe the weight of the scientific evidence for the identified hazards and exposure. The risk evaluation must not consider costs or other nonrisk factors. A detailed summary and analysis of the final risk evaluation rule is available in our June 26, 2017, memorandum, “EPA Issues Final TSCA Framework Rules.”

Draft Risk Evaluation for MC

According to the draft risk evaluation, MC “has a wide-range of uses, including as a solvent, propellent, or processing aid or functional fluid in the manufacturing of other chemicals. A variety of consumer and commercial products use methylene chloride as a solvent including sealants, automotive products, and paint and coating removers.” The draft risk evaluation states that MC “is currently manufactured, processed, distributed, used, and disposed of as part of industrial, commercial, and consumer conditions of use.” The leading applications for MC include as a solvent in the production of pharmaceuticals and polymers, metal cleaning, production of HFC-32 (refrigerant blend), and as an ingredient in adhesives and paint removers. EPA evaluated the following categories of conditions of use: manufacturing; processing; distribution in commerce; industrial, commercial, and consumer uses; and disposal. According to EPA, the total aggregate production volume ranged from 230 to 264 million pounds between 2012 and 2015.

The draft risk evaluation states that EPA’s initial determinations of unreasonable risk for the specific conditions of use of MC listed below are based on health risks to workers, occupational non-users (ONU), consumers, or bystanders from consumer use. According to the draft risk evaluation, risks to the general population either were not relevant for these conditions of use or were evaluated and not found to be unreasonable.

Unreasonable Risk to the General Population

As part of the problem formulation for MC, EPA identified exposure pathways covered under the jurisdiction of other federal statutes regulating chemical exposures, administered by EPA, that “adequately assess and effectively manage exposures and for which long-standing regulatory and analytical processes already exist,” i.e., the Clean Air Act (CAA), Safe Drinking Water Act (SDWA), Clean Water Act (CWA), and Resource Conservation and Recovery Act (RCRA). The draft risk evaluation states that “EPA believes this TSCA risk evaluation should focus on those exposure pathways associated with TSCA uses that are not subject to the regulatory regimes discussed above because these pathways are likely to represent the greatest areas of concern to EPA.” Exposures to MC by receptors (i.e., general population) may occur from industrial and/or commercial uses; industrial releases to air, water, or land; and other conditions of use, and as described above, other environmental statutes administered by EPA adequately assess and effectively manage these exposures. Therefore, “EPA did not evaluate hazards or exposures to the general population in this risk evaluation, and there is no risk determination for the general population.”

Unreasonable Risk to Workers

EPA evaluated workers’ acute and chronic inhalation and dermal occupational exposures for cancer and non-cancer risks and determined whether any risks indicated are unreasonable. The drivers for EPA’s determination of unreasonable risk for workers are central nervous system effects resulting from acute inhalation exposure, liver toxicity from chronic inhalation exposure, or both. According to the draft risk evaluation, the risks identified for workers are generally linked to acute and chronic inhalation exposures. EPA evaluated dermal exposure for workers and did not find these risks to be unreasonable. The determinations reflect the severity of the effects associated with the occupational exposures to MC and incorporate consideration of expected personal protective equipment (PPE). For workers, EPA determined that the conditions of use that presented unreasonable risks included processing MC into a formulation or mixture; all but two industrial and commercial uses; and disposal.

Unreasonable Risks to ONUs

EPA evaluated ONU acute and chronic inhalation occupational exposures for cancer and non-cancer risks and determined whether any risks indicated are unreasonable. The drivers for EPA’s determination of unreasonable risks to ONUs are central nervous system effects resulting from acute inhalation exposure, liver toxicity resulting from chronic inhalation exposure, and cancer effects (liver and lung tumors) from chronic inhalation exposure. Generally, risks identified for ONUs are linked to acute and chronic inhalation exposures. The determinations reflect the severity of the effects associated with the occupational exposures to MC and the expected absence of PPE for ONUs. For dermal exposures, because ONUs are not expected to be dermally exposed to MC, dermal risks to ONUs generally were not identified. For inhalation exposures, EPA, where possible, estimated ONU exposures and described the risks separately from workers directly exposed. For ONUs, EPA determined that the conditions of use that presented unreasonable risks included import of MC, processing MC as a reactant in several industrial sectors, some industrial and commercial uses, and disposal. EPA determined in some cases that a condition of use presented an unreasonable risk not only to workers but also ONUs; in other cases, EPA determined that a condition of use presented an unreasonable risk only to one or the other. This resulted from expectations regarding PPE use by workers or uncertainty regarding ONU exposures.

Unreasonable Risk to Consumers

EPA evaluated consumer acute inhalation and dermal exposures for non-cancer risks and determined whether the risks indicated are unreasonable. The driver for EPA’s determination of unreasonable risk is central nervous system effects from acute inhalation or dermal exposure. Generally, risks for consumers were indicated by acute inhalation and dermal exposure at medium and high intensity use. For consumers, EPA determined that all but two consumer conditions of use present unreasonable risks.

Unreasonable Risk to Bystanders (from Consumer Uses)

EPA evaluated bystander acute inhalation exposures for non-cancer risks and determined whether the risks indicated are unreasonable. The driver for EPA’s determination of unreasonable risk is central nervous system effects from acute inhalation exposure. Generally, risks for bystanders were indicated by acute inhalation exposure scenarios at medium and high intensity use. Because bystanders are not expected to be dermally exposed to MC, EPA did not identify dermal non-cancer risks to bystanders. When EPA determined that a condition of use presented risks to consumers, unreasonable risks were often, but not always, identified for bystanders.

Questions and Answers (Q&A) Regarding MC

EPA’s web page regarding the draft risk evaluation for MC includes the following Q&As regarding MC:

  • What should the public do in the meantime regarding products containing, or uses of, MC? For any chemical product, EPA strongly recommends that users carefully follow all instructions on the product’s label to ensure proper use, eliminating undue risk for harmful exposure. Workers using MC products should continue to follow label instructions and applicable workplace regulations and should properly use appropriate PPE when necessary.
  • I use products containing MC in my workplace. What should I do? Workers using MC products should continue to follow label instructions and applicable workplace regulations and should properly use appropriate PPE, as needed.
  • Are there alternatives for MC? There are many solvents on the market, some of which might be suitable replacements for MC depending on the condition of use. EPA has done some analysis of alternatives to MC with respect to paint and coating removal products and there are a variety of alternatives available. These include other chemical products as well as mechanical methods. Additional work on identifying whether alternatives exist for other MC uses will take place in the coming months.

Commentary

As noted in our earlier memorandum on this topic, the risk evaluation of MC is interesting for several reasons, including the presence of an earlier EPA risk assessment of MC from 2014 and the regulatory actions that have been proposed or taken on MC’s paint and coating removal use. Now that the draft risk evaluation has been released for review, its scope of risk concerns as outlined above can only now be appreciated. The unreasonable risk issues identified by EPA go far beyond the paint and coating removal use that was the focus of EPA’s recent regulatory efforts and include a wide and almost comprehensive array of MC’s current occupational and non-occupational uses and exposures, consumer uses, and exposures to bystanders from consumer uses. In its approach to general population risk, a policy approach that has been used previously in risk evaluations but is nonetheless controversial, EPA has taken the position that the protections afforded by regulations under other environmental statutes sufficiently assess and effectively manage general population exposures. Based on this position, EPA did not identify a need to include those aspects in its risk evaluation and did not make a general population risk determination. Whether EPA’s policy rationale for not including these exposures in its evaluation will be convincing to the public will be interesting to observe. At the same time, we note that, all things considered -- especially the many large and complex challenges that EPA faces in completing the first ten risk evaluations as well as the subsequent need to take the regulatory actions required by those risk evaluations when issued in final -- there is a certain logic and pragmatic appeal to this aspect of EPA’s approach. A final comment is to note that the new risk evaluation includes risk conclusions concerning MC’s environmental effects, whereas the earlier risk assessment did not consider the environmental impact.