Vinyl Chloride Among Next Five Chemicals Designated for TSCA Risk Evaluation
On Dec. 18, 2024, EPA announced that it had designated five more chemicals as high-priority substances that will undergo risk evaluations under the Toxic Substances Control Act. The chemicals are all known or probable carcinogens: acetaldehyde, acrylonitrile, benzenamine, 4,4’-methylene bis(2-chloroaniline) or MBOCA, and vinyl chloride. EPA also announced that it has selected five more chemicals to determine whether the agency should perform risk evaluations for them: benzene, ethylbenzene, naphthalene, styrene, and 4-tert-octylphenol.
Vinyl chloride, one of the substances to undergo risk evaluation, made headlines in February 2023 as one of several hazardous substances that first responders vented from derailed train cars near East Palestine, Ohio. The chemical, a known carcinogen, is primarily used in the manufacturing of plastics such as polyvinyl chloride. According to EPA, concerns over the health effects of vinyl chloride prompted Congress to promulgate the original TSCA in 1974.
Acetaldehyde is mainly used in manufacturing and processing adhesives, petrochemicals, and other chemicals, and in intermediates for products like packaging and construction materials. Acetaldehyde exposure may cause respiratory irritation. Exposure to acrylonitrile, which is used to process plastics, paints, petrochemicals, and other chemicals, is also associated with respiratory irritation. Benzenamine exposure may affect the blood, fetal development, and reproduction, and the chemical is used to manufacture and process dyes and pigments, petrochemicals, plastics, resins, and other chemicals. The substance MBOCA is used in the manufacturing and processing of rubbers, plastics, resins, and other chemicals. EPA states that there is “extensive evidence” showing that exposure to MBOCA may damage genetic material in cells and lead to other adverse health effects, especially in infants and children.
On Dec. 31, 2024, EPA released for public comment a preliminary list of manufacturers and importers that may be subject to fees for the five chemicals newly designated as high-priority substances. This and other supporting documents may be accessed in the docket EPA-HQ-OPPT-2024-0501 at Regulations.gov.
Of the five additional chemicals selected for potential prioritization under TSCA, benzene is a known carcinogen that causes leukemia, as well as immune system effects and developmental abnormalities. Ethylbenzene, naphthalene, and styrene are probable carcinogens also associated with various health effects, and 4-tert-octylphenol is linked with kidney inflammation and impaired fertility. All five substances are used in a range of manufacturing and processing applications.
EPA’s statutory prioritization process is expected to take nine to 12 months and will end when the agency determines whether the chemicals in question present an unreasonable risk to human health or the environment. If so, the agency must immediately begin the risk management process. In the past year, EPA has streamlined the prioritization process by updating its technology, implementing recommendations from the Science Advisory Committee on Chemicals, and making more information on the chemicals of concern publicly available earlier in the process. The agency has opened a public comment period ending March 18, 2025. The dockets for each of the chemicals being considered for prioritization can be accessed through EPA’s website.
More information about the chemicals recently selected for risk assessment, as well as those undergoing prioritization, may be found in EPA’s Dec. 18 press release.
