The U.S. Environmental Protection Agency announced on December 18, 2024 that it will formally designate five known or probable carcinogens as High-Priority Substances (HPS) to undergo a risk evaluation under the Toxic Substances Control Act (TSCA): acetaldehyde, acrylonitrile, benzenamine, 4,4’-methylene bis(2-chloroaniline) (MBOCA), and vinyl chloride.
Risk evaluation could lead to restrictions on manufacturing, use or disposal of the chemicals to eliminate unreasonable risk to human health or the environment, or to low-risk designation with no limitations.
Vinyl chloride is primarily used in the manufacturing and processing of plastic materials like polyvinyl chloride (PVC), plastic resins, and other chemicals. Many of these materials are used for pipes employed widely in the groundwater supply and monitoring and in insulating materials and consumer goods. This chemical was also involved in the Norfolk Southern train derailment in East Palestine, Ohio. Exposure to vinyl chloride may result in a range of harmful health effects such as liver toxicity. Vinyl chloride is also a known human carcinogen.
In the 1970s, the White House Council on Environmental Quality and EPA officials raised serious concerns about the health impacts of vinyl chloride. These concerns were the impetus for Congress to write the “original TSCA” law in 1976 to ensure chemicals were made and used safely.
Approximately two million miles of PVC pipe have been installed for utility water and wastewater lines in North America , not including indoor PVC water supply and wastewater plumbing in homes and commercial structures.
4,4’-methylene bis(2-chloroaniline) is used as a curing agent for polyurethane that has been used for environmentally friendly grouts used to contain groundwater contamination or preferentially control groundwater migration in sensitive areas.
In the coming weeks, EPA will also release for public comment preliminary lists of manufacturers (including importers) subject to fees for the five chemicals designated as HPS under TSCA. The preliminary lists will soon be available in the docket EPA-HQ-OPPT-2024-0501 at the Regulations.gov page. Additionally, the EPA will host a webinar on the list of fee payers, including steps to self-identify, how to certify as meeting an exemption, and how to report production volume at 1 p.m. ET on January 14.
The EPA also announced the beginning of the nine- to 12-month statutory process to prioritize the next five chemicals under TSCA to determine whether to initiate risk evaluations on them: benzene, ethylbenzene, naphthalene, styrene, and 4-tert-octylphenol.
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