The U.S. Environmental Protection Agency (EPA) has announced the designation of five known or probable carcinogens as High-Priority Substances (HPS) under the Toxic Substances Control Act (TSCA). These substances—acetaldehyde, acrylonitrile, benzenamine, 4,4’-methylene bis(2-chloroaniline) (MBOCA), and vinyl chloride—will undergo risk evaluations to assess their potential health and environmental impacts.
"Today we begin another five chemical risk evaluations under our nation’s strengthened chemical safety law and start the yearlong process to initiate five more," stated Michal Freedhoff, Assistant Administrator for the Office of Chemical Safety and Pollution Prevention. "These risk evaluations will be used to determine how to protect people from harmful chemical exposures."
The EPA had begun prioritizing these chemicals in December 2023. The agency has improved its prioritization process by using advanced software for earlier information review and enhancing systematic review approaches based on recommendations from the Scientific Advisory Committee on Chemicals.
In July 2024, EPA proposed these chemicals for evaluation, making more information available earlier in the process compared to previous evaluations. The goal is to determine if these substances pose an unreasonable risk without considering costs or other non-risk factors.
Vinyl chloride is primarily used in manufacturing plastics like polyvinyl chloride (PVC). Exposure may cause liver toxicity and it is a known human carcinogen. Acetaldehyde is used in producing adhesives and petrochemicals; it can irritate respiratory systems and is a probable human carcinogen. Acrylonitrile's primary uses include plastic materials production; it also poses respiratory risks as a probable carcinogen. Benzenamine is involved in dyes and pigments manufacturing with potential blood-related health effects. MBOCA is linked to genetic damage when exposed, particularly affecting infants and children.
Additionally, EPA will soon release preliminary lists of manufacturers subject to fees related to these chemicals on Regulations.gov. A webinar on this topic will occur on January 14, 2025.
Simultaneously, EPA begins prioritization for benzene, ethylbenzene, naphthalene, styrene, and 4-tert-octylphenol for future evaluation processes under TSCA guidelines.
Benzene exposure affects immune systems and fetal development; it's a known human carcinogen causing leukemia. Ethylbenzene poses risks such as liver damage and hearing loss; it's a probable human carcinogen linked to lung tumors in animals. Naphthalene may destroy red blood cells; it's associated with nasal tumors in animals as a probable carcinogen. Styrene exposure could result in memory loss; it's linked with various cancers according to epidemiological data. Lastly, 4-tert-octylphenol can impair fertility due to kidney inflammation.
EPA invites public comments over the next 90 days concerning usage details of these chemicals alongside any additional relevant information about their hazards.
