On June 15, 2024, the U.S. Environmental Protection Agency (EPA) issued a proposed rule under Section 6(a) of the Toxic Substances Control Act (TSCA) that would protect workers and consumers from exposure to N-methylpyrrolidone (NMP). 89 Fed. Reg. 51134. To address the identified unreasonable risk, EPA proposes to: prohibit the manufacture (including import), processing, distribution in commerce, and use of NMP in several occupational conditions of use (COU); require worker protections through an NMP workplace chemical protection program (WCPP) or prescriptive controls (including concentration limits) for most of the occupational COUs; require concentration limits on a consumer product; regulate certain consumer products to prevent commercial use; and establish recordkeeping, labeling, and downstream notification requirements. Comments are due July 29, 2024. Under the Paperwork Reduction Act (PRA), comments on the information collection provisions are best assured of consideration if the Office of Management and Budget (OMB) receives a copy of the comments on or before July 15, 2024.

According to EPA’s June 5, 2024, press release, NMP is used to manufacture and produce many electronics, polymers, agricultural chemicals, and petrochemical products. EPA states that NMP is used in the production of specialized electronics, such as semiconductors and magnet wire, as well as lithium-ion batteries used in a wide variety of applications, including aerospace vehicles and electronic devices. EPA notes that NMP “also has numerous other industrial, commercial and consumer applications, including adhesives and sealants, paints and coatings, paint removers, lubricants, automotive care products, degreasers, cleaning and furniture care products.”

The proposed rule states that pursuant to TSCA Section 6(b), EPA determined that NMP presents an unreasonable risk of injury to health, without consideration of costs or other non-risk factors, including an unreasonable risk to potentially exposed or susceptible subpopulations (PESS) identified as relevant to the 2020 NMP risk evaluation, under the COUs. EPA states that the term “conditions of use” is defined at TSCA Section 3(4) to mean the circumstances under which a chemical substance is intended, known, or reasonably foreseen to be manufactured, processed, distributed in commerce, used, or disposed of. EPA notes that all TSCA COUs of NMP are subject to the proposed rule. Accordingly, to address the unreasonable risk, EPA proposes, under TSCA Section 6(a), to:

• Prohibit the manufacture (including import), processing, distribution in commerce, and use of NMP for five occupational COUs;
• Require container size limits and labeling requirements for the manufacture (including import), processing, and distribution in commerce of NMP for seven consumer uses;
• Require prescriptive controls, including concentration limits and personal protective equipment (PPE) for seven occupational COUs;
• Require strict workplace controls, including an NMP WCPP, that would include requirements to prevent direct dermal contact with NMP for all other occupational COUs, including the commercial use of paints and coatings and paint, coating, and adhesive removers containing high concentrations of NMP in uses essential to the missions of the Department of Defense (DOD) and National Aeronautics and Space Administration (NASA);
• Require a concentration limit on NMP for the import, processing, and distribution in commerce of one consumer use; and
• Establish recordkeeping and downstream notification requirements.

In addition, EPA proposes to amend the general provisions of 40 C.F.R. Part 751, Subpart A, to define the following terms so that these definitions may be commonly applied to this and other rules under TSCA Section 6 that would be codified under 40 C.F.R. Part 751: “Direct dermal contact,” “Exposure group,” and “Restricted area.” EPA notes that it may codify these definitions in another rule under 40 C.F.R. Part 751 prior to the publication of the final rulemaking for NMP. EPA seeks public comment on all aspects of the proposed rule.

Commentary

The proposed NMP rule demonstrates that EPA’s approach to risk management continues to evolve as EPA learns more during its early implementation of TSCA Section 6. We are pleased that EPA did not seek to ban most COUs and acknowledges the value and efficacy of workplace exposure protection. We agree with EPA’s focus on dermal exposure. NMP is well absorbed dermally and is also a penetration aid for solutes, so it is critical for workers not to be exposed dermally. EPA’s WCPP requires review of which workers are reasonably likely to be exposed, including whether they may handle equipment or empty containers that may have NMP present. The WCPP also requires employers to evaluate NMP under the industrial hygiene (IH) hierarchy of controls: elimination, substitution, engineering controls, and administrative controls, including an evaluation of feasibility and effectiveness of such controls. If exposures cannot be eliminated, dermal protection is required. If inhalation exposure occurs during use of NMP in paints or coatings or removal of paints or coatings, respiratory protection is also required.

EPA did not find unreasonable risk for consumer products containing NMP below 45% by weight. Given this, and that EPA found a WCPP to be protective, we are surprised that EPA is proposing to ban certain commercial and industrial uses. EPA is again banning uses for which it has insufficient exposure data rather than simply imposing a WCPP (or a combination of a WCPP and concentration limit). Whether this course of action meets or exceeds the “extent necessary” provision of TSCA Section 6(a) remains to be seen. It also illustrates the need for stakeholders throughout the supply chain to develop and provide to EPA measures taken in the workplace demonstrating that workers are properly protected through the hierarchy of controls. Too often, downstream users rely on their suppliers to advocate for a substance. EPA needs release and exposure information throughout the supply chain, and manufacturers are not well suited to provide such information to EPA on behalf of users. EPA has requested information on these COUs, so users have an opportunity to provide EPA with the necessary information, but we hope that for future risk evaluation and risk management activities, downstream customers engage more fully with EPA and engage earlier in the process.

We are also pleased to see that EPA has again provided a threshold for the applicability of the rule and that EPA has selected 0.1% as the de minimis threshold, as it did for methylene chloride. For discussion, see our memorandum dated May 17, 2024. EPA correctly acknowledges that zero is not a reasonable threshold for the applicability of a rule because a manufacturer or importer cannot prove the absence of a substance, only presence below a level of detection. EPA found that 0.1% was sufficiently protective and that a lower de minimis threshold is not required, so relying on the 0.1% de minimis threshold from the hazard communication standard is justified.

A reader of the proposed TSCA requirements might recognize the aspects of a well-crafted and -executed hazard communication, training, and workplace protection plan under the Occupational Safety and Health Administration (OSHA). This begs the question of whether the TSCA rule is necessary for protecting workers, although we recognize the different statutory mandates under the Occupational Safety and Health Act of 1970 (OSH Act) versus TSCA, which requires an evaluation of PESS.

A more significant concern with EPA’s proposed rule is its reliance on non-reproducible science as the basis for its risk management actions. This is a common theme with EPA’s risk evaluations and risk management activities, particularly for NMP and trichloroethylene. For discussion, see our memorandum dated November 3, 2023.

We encourage interested persons to review EPA’s proposed rule and to submit comments, as necessary. EPA’s proposal includes reasonable decisions, such as focusing on protecting against dermal exposures, but the lingering, underlying scientific issues are troubling because they will likely set precedence with EPA’s continued use of science, despite not being reproducible in subsequent, more robust studies. This outcome is unlikely to change in future risk evaluations unless regulated entities challenge EPA’s final rule and seek a court’s help in addressing EPA’s failure to comply with the scientific standards under TSCA Section 26.