The U.S. Environmental Protection Agency (EPA) published the final risk evaluation for carbon tetrachloride on November 4, 2020. The EPA found unreasonable risks to workers and occupational non-users (ONU) for 13 of the 15 conditions of CCl4 use, but no unreasonable risks to the environment. According to the EPA, there are no consumer uses of this chemical. Most agree the findings are not unexpected. This article explains the assessment and the results.
Background
TSCA Section 6 requires the EPA to conduct risk evaluations to determine whether a chemical substance presents an unreasonable risk of injury to health or the environment. For each risk evaluation, the agency must publish a document outlining the scope of the risk evaluation, including the hazards, exposures, conditions of use, and the potentially exposed or susceptible subpopulations. The risk evaluation must not consider costs or other nonrisk factors.
Risk Evaluation for Carbon Tetrachloride
The EPA evaluated workplace exposures and water releases for industrial/commercial uses of CCl4. The EPA did not identify any “‘legacy uses’ (i.e., circumstances associated with activities that do not reflect ongoing or prospective manufacturing, processing or distribution) or ‘associated disposal’ (i.e., future disposal from legacy uses) of carbon tetrachloride.” Therefore, the EPA did not add any such uses or disposals to the scope of the risk evaluation following the issuance of the opinion in Safer Chemicals, Healthy Families v. EPA. The EPA did not evaluate “legacy disposal” (i.e., disposals that have already occurred) in the risk evaluation “because legacy disposal is not a ‘condition of use’ under Safer Chemicals.”
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The EPA made the following final risk evaluation findings, stating, that in making these determinations, it considered the hazards and exposure, magnitude of risk, exposed population, severity of the hazard, uncertainties and other factors.
• There are no consumer uses of this chemical. In the final risk evaluation, the EPA reviewed 15 conditions of use, all of which are associated with industrial and commercial work and primarily involve the manufacturing of other chemicals.
• The EPA assessed the impact of CCl4 on aquatic and sediment-dwelling species through surface water and sediment exposures, and on terrestrial species. After reviewing these data, the agency found no unreasonable risk to the environment from any conditions of use.
• The EPA found unreasonable risks to workers and ONUs from 13 of the 15 conditions of use of CCL4. The agency found unreasonable risks from most commercial uses of CCl4 to workers in direct contact and workers nearby but not in direct contact with CCL4 (known as ONUs). Unreasonable risks to workers and ONUs include potential cancer and liver toxicity effects from long-term (chronic) inhalation or dermal (through the skin) exposures. Carbon tetrachloride does not pose an unreasonable risk for two conditions of use: when processed as a reactant in reactive ion etching and in distribution in commerce.
Discussion
The draft risk evaluation did not find any unreasonable risks for workers. This changed substantially in the final version as the EPA determined that 13 of 15 conditions of use presented unreasonable risks to workers. Relative to the draft document, the EPA found unreasonable risks to ONUs for several additional conditions of use. The bottom line, as noted above, is that 13 of 15 conditions of use presented unreasonable risks to both workers and ONUs and that CCl4 will, as required by TSCA, be regulated as needed under Section 6. Unlike other risk evaluations, the EPA concluded that CCl4 does not have “legacy” conditions of use.
The EPA did not evaluate hazards or exposures to the general population in this risk evaluation. The EPA excluded these exposures based on TSCA’s function as a “gap-filling” statute. The EPA regulates CCl4 under the Clean Water Act; Clean Air Act; Federal Insecticide, Fungicide, and Rodenticide Act; Resource Conservation and Recovery Act; and Emergency Planning and Community Right-to-Know Act. As a result, the EPA states it “tailored the scope of the risk evaluation” using authorities in TSCA Sections 6(b) and 9(b)(1). The latter concerns TSCA’s relationship to other laws administered by the EPA. The agency has used this argument in other final risk evaluations, and it remains to be seen if this approach prompts legal challenge.
