In December of 2023, the EPA announced that it was beginning the process to prioritize five additional toxic chemicals, including vinyl chloride, for risk evaluation. This began the 9-12 month process statutory time frame during which the EPA must designate the chemical substances as either high or low priority.

Screening Review
During this phase of the process, the EPA reviewed: The hazard and exposure potential of the chemical substance; Persistence and bioaccumulation;
Potentially exposed or susceptible subpopulations; Storage near significant sources of drinking water; The conditions of use or significant chances in the conditions of use of the chemical substance; and  the volume or significant changes in the volume of the chemical substance manufactured or processed.

The EPA proposed to designate five chemicals including vinyl chloride as High-Priority Substances for risk evaluation under TSCA. If EPA finalizes these designations as proposed, the agency would immediately move forward with the risk evaluation process.

 Prioritization is the first step under EPA’s authority to regulate existing chemicals currently on the market and in use. EPA’s proposed designations are not themselves a finding of risk. If EPA finalizes these designations, the agency will initiate risk evaluations for these chemicals to determine whether they present an unreasonable risk to human health or the environment under the TSCA conditions of use (the way the chemical is made and used), which the agency is required to complete within 3-3.5 years. If at the end of the risk evaluation process EPA determines that a chemical presents an unreasonable risk to health or the environment, the agency must begin the risk management process to take action to eliminate these unreasonable risks.

The EPA has conducted a preliminary screening and technical review of large data sets to more efficiently identify relevant information for prioritization and risk evaluation and can easily flag information that may be useful to retrieve later in the risk evaluation process. As a result, EPA now has a head start on risk evaluations.

After considering public comments, the EPA designated vinyl chloride as a high-priority substance under the Toxic Substances Control Act. This designation acknowledges the significant risks posed by this hazardous chemical, which is widely used in water infrastructure materials. In addition to the proposed designation, the EPA published the information, analysis, and basis used to make the designation. The EPA will take public comment on the proposed designation and supporting materials for 90 days.

Vinyl chloride has been designated a high-priority substance, meaning EPA determined that it may pose an unreasonable risk to human health or the environment, and is now undergoing a formal risk evaluation by the EPA.
In January 2025, EPA released the draft scope for this evaluation, and the public comment period concluded in April 2025. The agency is now in the full risk evaluation phase, which is expected to take 3–3.5 years to complete.
In December 2024, EPA designated vinyl chloride as a high-priority substance for risk evaluation under TSCA - a determination that vinyl chloride may pose an unreasonable risk to human health or the environment. In January 2025, EPA released the draft scope for the risk evaluation, and the public comment period closed on April 2, 2025. The agency is now in the full risk evaluation phase, which has a statutory timeframe of 3–3.5 years. The outcome of this process could range from new use restrictions to significant regulatory action affecting PVC products, including pipes used in drinking water systems. Regardless of the pace or outcome of EPA’s review, the underlying health and environmental concerns associated with vinyl chloride are well established and will not change with the regulatory timeline

Risk Management determination happens within one year of the final risk evaluation regarding the chemical substance being published. If at the end of the risk evaluation process the EPA determines that a chemical presents an unreasonable risk to the health or the environment, the chemical must immediately move to risk management. The EPA is required to implement via regulation, regulatory restrictions on the manufacture, processing, distribution, use or disposal of the chemical to eliminate the unreasonable risk. EPA is given a range of risk management options under TSCA, including labeling, record keeping or notice requirements, actions to reduce human exposure or environmental release, and a ban of the chemical or certain uses. Like the prioritization and risk evaluation processes, there is an opportunity for public comment.