On January 16, 2025, the U.S. Environmental Protection Agency (EPA) announced the availability of and requested public comment on the draft scope of the risk evaluation to be conducted under the Toxic Substances Control Act (TSCA) for vinyl chloride. 90 Fed. Reg. 4738. EPA notes that under TSCA, the scope documents must include the conditions of use (COU), hazards, exposures, and the potentially exposed or susceptible subpopulations (PESS) that EPA expects to consider in conducting its risk evaluation. EPA states that the purpose of risk evaluations under TSCA is to determine whether a chemical substance presents an unreasonable risk of injury to health or the environment under the COUs, including unreasonable risk to PESS identified as relevant to the risk evaluation by EPA, and without consideration of costs or non-risk factors. Comments are due March 3, 2025.

Reasonably Available Information

According to the draft scope document, EPA leveraged the data and information sources described in the Proposed Designation of Vinyl Chloride as a High-Priority Substance for Risk Evaluation to inform the development of the draft scope document. EPA applied systematic review methods to identify and screen reasonably available information across multiple evidence streams (i.e., chemistry, fate, release and engineering, exposure, and hazard) for consideration in the risk evaluation. This information includes the hazards, exposures, PESS, and TSCA COUs that may help inform the risk evaluation for vinyl chloride. EPA focused on the data collection phase during prioritization and preparation of the draft scope document; in contrast, according to EPA, the data extraction, evaluation, and integration stages will occur during the development of the draft risk evaluation and thus are not part of the scoping activities. EPA plans to consider additional information identified following release of the draft and final scope, as appropriate, in developing the draft risk evaluation — including Chemical Data Reporting (CDR) information received in November 2024.

COUs

EPA states that it plans to evaluate manufacturing (including importing); processing; distribution in commerce; industrial, commercial, and consumer uses; and disposal of vinyl chloride in the risk evaluation. According to EPA, vinyl chloride is manufactured domestically and imported into the United States. Vinyl chloride is processed as a reactant; incorporated into a formulation, mixture, or reaction product; incorporated into articles; and used in other industrial and commercial processes. The processing activities identified in the draft scope document also include the repackaging and recycling of vinyl chloride. EPA notes that all of the identified industrial, commercial, and consumer uses are related to vinyl chloride serving as a monomer in plastics — primarily polyvinyl chloride (PVC) — and other polymers. EPA identified these COUs from information reported through CDR, public comments, and other publicly available data sources, including emissions databases, safety data sheets (SDS), published literature, and company websites.

Conceptual Model

The conceptual models are graphical depictions of the actual or predicted relationships of COUs, exposure pathways, exposure routes, hazards, and populations throughout the lifecycle of vinyl chloride. EPA states that it considered reasonably available information, including public comments, in considering the exposure pathways, exposure routes, and hazards it expects to evaluate in the risk evaluation. Furthermore, EPA’s plan for evaluating exposure in the scope of the risk evaluation considers major or minor exposure pathways and routes based on physical and chemical information, release information, fate and transport properties, and other information such as industry standards in PVC production.

Analysis Plan

The analysis plan for vinyl chloride outlines the general science approaches that EPA plans to use for the various evidence streams (i.e., releases, fate, engineering, exposure, and hazard) supporting the risk evaluation. EPA states that the analysis plan is based on its knowledge of vinyl chloride to date that includes a review of identified information. EPA notes that should additional data or approaches become reasonably available, it plans to consider them for the draft risk evaluation.

Peer Review

EPA states that the draft risk evaluation for vinyl chloride will be peer reviewed as required by the TSCA Risk Evaluation Rule (89 Fed. Reg. 37028). Peer review will be conducted in accordance with relevant and applicable methods for chemical risk evaluations, including using EPA’s Peer Review Handbook and other methods consistent with TSCA Section 26.

Commentary

Vinyl chloride is no stranger to the regulatory spotlight and stakeholders can be expected to gather and share robust, pertinent, and accurate data with EPA to assist the Agency in this important initiative. Given the size of the vinyl industry and its contributions to the economy, stakeholders are urged to collaborate with EPA to ensure the scope of the risk evaluation is properly calibrated and supported by the best available information.