As part of the Environmental Protection Agency’s (EPA) decision to determine risk via a “whole chemical” approach for Toxic Substances Control Act (TSCA) risk evaluations, the Agency has released a final revised risk determination for n-methylpyrrolidone (NMP). The EPA has determined that NMP presents an unreasonable risk of injury to health under its current conditions of use.
- 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 ( 15 U.S.C. § 2601 et seq., 2016). 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. TSCA then imposed additional statutory requirements to ensure that risk evaluations and potential risk management rules continued on a rolling basis as the risk evaluations are completed.
- 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.”
- The EPA evaluates hazard and exposure, uses 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. The evaluation excludes consideration of costs or other non-risk factors.
- Weight of scientific evidence means a systematic review method, applied in a manner suited to the nature of the evidence or decision, that uses a pre-established protocol to comprehensively, objectively, transparently, and consistently, identify and evaluate each stream of evidence, including strengths, limitations, and relevance of each study and to integrate evidence as necessary and appropriate based upon strengths, limitations, and relevance.
- Conditions of use is defined under TSCA as “the circumstances, as determined by the Administrator, under which a chemical substance is intended, known, or reasonably foreseen to be manufactured, processed, distributed in commerce, used or disposed of.” The EPA states that it may determine that certain uses fall outside the definition of “conditions of use” during the risk evaluation scoping process and may decide to narrow the scope of the risk evaluation further, potentially excluding conditions of use that present low risk.
- The Risk Evaluation process is the second step, following Prioritization and before Risk Management, in EPA’s existing chemical process under TSCA. EPA bases the risk determination on the information and supporting documents provided in the risk evaluation. The risk evaluation determines whether a chemical substance presents an unreasonable risk to health or the environment, under the conditions of use.
- In accordance with TSCA Section 6(b), if EPA finds unreasonable risk under the conditions of use in any final risk evaluation, the EPA will propose actions to eliminate the unreasonable risk within the required timeframe.
- n-Methylpyrrolidone (NMP) is a solvent utilized in several industries, from paint and paint removal products to petrochemical manufacturing. Between 100 and 250 million pounds of NMP were reportedly either imported into the U.S. or manufactured in the country according to data received from the 2020 Chemical Data Reporting rule.
- The EPA published the initial risk evaluation for NMP in December 2020. In the risk evaluation, the EPA identified 37 separate conditions of use, with 26 of those conditions presenting an unreasonable risk. Most consumer uses of the product (such as using NMP as a paint stripper) were considered to not present an unreasonable risk, but similar industrial and commercial uses were considered to present an unreasonable risk.
December 2022 final revised risk determination
- On December 19, 2022, the EPA published notice for the final revised risk determination in the Federal Register. The newly published final revised risk determination changes the determination to find that NMP use presents an unreasonable risk of injury to health under its current conditions of use. The EPA reconsidered two major factors from the 2020 risk evaluation: first, the EPA analyzed NMP as a “whole chemical” rather than via conditions of use and second, the EPA no longer made assumptions regarding the use of personal protective equipment (PPE).
- The EPA’s analysis of NMP led to three new conditions of use, specifically covering import, processing, commercial use, consumer use, with 29 of the 37 risks determined to present an unreasonable risk. However, because the EPA now determines risk based on the “whole chemical” rather than via conditions of use, the EPA determined that NMP presented an unreasonable risk to human health.
- In addition, the final revised risk determination touched on the EPA’s change in policy regarding PPE. The new baseline assumes that PPE may not be used based on employers that may be out of compliance with Occupational Safety and Hazard Administration (OSHA) regulations, and that many chemical-specific Permissible Exposure Limits (PELs) are considered by OSHA to be inadequate for the purposes of protecting worker health.
- The next steps will involve the EPA proposing risk management regulatory action to the extent necessary so that NMP no longer presents an unreasonable risk. The use of PPE and other methods to reduce NMP exposure risk could be included in these risk management actions, but the actions may take some time to be published by the EPA.
- Based on EPA responses to comments on other chemicals that have been reassessed under the new EPA methods, the EPA may take into consideration specific uses of NMP as well as industry-standard practices for PPE use surrounding NMP. As NMP is widely used across the country, it is likely that there will be some future rules regarding risk management that may be more lenient towards industry and consumer uses.
Contains previous research by Walker Livingston.
To contact the author of this analysis, please email Walker Livingston ( [email protected])
To contact the editor of this analysis, please email Patricia Iscaro ( [email protected])