EPA Initiates Risk Evaluations for Five Chemicals, Begins Prioritizing Five More

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On December 18, 2024, EPA designated five chemicals as high-priority substances, automatically initiating risk evaluations for them under the Toxic Substances Control Act (TSCA).  In a separate rulemaking, EPA also initiated the prioritization process for another round of five substances.

The five chemicals now undergoing risk evaluations are:

  • Vinyl chloride (CASRN 75-01-4)
  • Acetaldehyde (CASRN 75-07-0)
  • Acrylonitrile (CASRN 107-13-1)
  • Benzenamine (CASRN 62-53-3)
  • 4,4’-methylene bis(2-chloroaniline) (MBOCA) (CASRN 101-14-4)

More on those substances can be found here.

The five chemicals newly identified for prioritization are:

  • 4-tert-Octylphenol (CASRN 140-66-9);
  • Benzene (CASRN 71-43-2);
  • Ethylbenzene (CASRN 100-41-4);
  • Napthalene (CASRN 91-20-3); and
  • Styrene (CASRN 100-42-5).

According to EPA, benzene is a known carcinogen while ethylbenzene, naphthalene, and styrene are probable carcinogens.  4-tert-octylphenol may cause kidney inflammation and impaired fertility.  All five chemicals were selected from the 2014 TSCA Work Plan and have uses in consumer products.  National production volumes range from tens of millions to tens of billions of pounds annually, according to Chemical Data Reporting (CDR) data.

Comments on EPA’s initialization of prioritization are due March 18, 2025.  There will be another opportunity for comment when the agency formally proposes to designate these substances as high priority, which will likely occur in summer 2025.

All 10 chemicals are also covered by a recently finalized health and safety reporting rule, which applies to 16 substances in total.  A blog post on the rule is forthcoming.