EPA Pursuing Prioritization for Five New Chemicals Under TSCA

Petrochemical plant at twilight

February 2, 2024

Agency seeks further screening information and begins mandated reporting of adverse human health and environmental effects under the Toxic Substances Control Act

The 90-day public comment period for five new chemicals to be regulated under the Toxic Substances Control Act (TSCA) is now open through March 18.

The Environmental Protection Agency (EPA) began the prioritization process for acetaldehyde, acrylonitrile, benzenamine, 4,4'-Methylenebis(2-Chlororaniline) (MBOCA), and vinyl chloride — all selected from the 2014 Work Plan chemicals list — in December 2023. EPA is also now requiring companies to submit records of significant adverse human health and environmental effects reported to have been caused by MBOCA before Feb. 26. 

TSCA's chemical risk evaluation process

Under the Frank R. Lautenberg Chemical Safety for the 21st Century amendments to TSCA, EPA must use a risk-based screening process to designate chemicals as either high-priority substances for further risk evaluation or low-priority substances that do not currently warrant risk evaluations. Potential candidates are reviewed through a 12-month statutory process called prioritization, which includes initiation, a proposed designation, and a final designation. At initiation, EPA formally announces which chemicals are entering prioritization; EPA then publishes the chemical information, analysis, and basis supporting the proposed designation; and with final designation, EPA immediately begins the risk evaluation process for a high-priority chemical substance. 

Since the final designation of the initial set of 20 high-priority substances was announced in December 2019, EPA has published final risk evaluations and proposed risk management measures for a subset of these designated chemicals (trichlorethylene, perchloroethylene, methylene chloride, carbon tetrachloride, and asbestos). 

To ensure a sustainable pipeline of existing chemicals are queued for risk evaluation, EPA must designate at least one high-priority chemical substance upon the completion of each subsequent risk evaluation, per TSCA section 6(b)(3)(C). EPA expects to initiate prioritization for five chemicals every year going forward.

EPA expands information-gathering authority for new toxic chemicals

Those wishing to supply information as part of the public comment period for the five priority chemicals can do so at under docket EPA-HQ-OPPT-2023-0601-0002

The agency is especially seeking information related to the chemicals' conditions of use and product volume. The mandate for companies to submit records of significant adverse human health and environmental effects reported to have been caused by MBOCA (CASRN: 101-14-4) (see EPA-HQ-OPPT-2023-0312-0001), invoked under the authority of TSCA section 8(c), is the agency's first such mandate in the last 30 years. To assist companies impacted by these reporting obligations, EPA has published several relevant guidance documents such as:

For industry stakeholders such as chemical and product manufacturers, staying abreast of the proposed chemicals being considered for risk evaluation and risk mitigation under TSCA is important for understanding future regulatory requirements and impacts to the chemical marketplace, including the need to respond to data reporting requests.

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Exponent's multidisciplinary teams of chemists, health scientists, epidemiologists, risk assessors, industrial hygienists, ecological and human health toxicologists, and regulatory experts can help you respond to data reporting requests, prepare TSCA new chemicals submissions, and conduct human health and ecological hazard and risk evaluations for existing chemicals on the TSCA inventory.