EPA Issues Draft Revision to Risk Determination for Carbon Tetrachloride and Finds Carbon Tetrachloride, as a Whole Chemical Substance, Presents an Unreasonable Risk
On August 29, 2022, the U.S. Environmental Protection Agency (EPA) announced the availability of and requested public comment on a draft revision to the risk determination for the carbon tetrachloride risk evaluation issued under the Toxic Substances Control Act (TSCA). 87 Fed. Reg. 52766. EPA states that the draft revision to the carbon tetrachloride risk determination reflects its announced policy changes to ensure the public is protected from unreasonable risks from chemicals in a way that is supported by science and the law. In the draft revision, EPA finds that carbon tetrachloride, as a whole chemical substance, presents an unreasonable risk of injury to health when evaluated under its conditions of use (COU). Comments are due September 28, 2022.
In addition, the revised risk determination does not reflect an assumption that all workers always appropriately wear personal protective equipment (PPE). EPA states that it understands that there could be occupational safety protections in place at workplace locations. According to EPA, not assuming use of PPE reflects EPA’s recognition that unreasonable risk may exist for subpopulations of workers who may be highly exposed because they are not covered by Occupational Safety and Health Administration (OSHA) standards, or their employers are out of compliance with OSHA standards, or because “many of OSHA’s chemical-specific permissible exposure limits [PEL] largely adopted in the 1970’s are described by OSHA as being ‘outdated and inadequate for ensuring protection of worker health.’”
In its August 29, 2022, press release, EPA states that 13 of the 15 COUs that EPA evaluated would drive the carbon tetrachloride whole chemical unreasonable risk determination due to risks identified for human health. Removing the assumption that workers always and appropriately wear PPE when making the whole chemical risk determination for carbon tetrachloride would not alter the COUs that drive the unreasonable risk determination for carbon tetrachloride. EPA states that without the assumed use of PPE, inhalation exposures to workers would now also drive the unreasonable risk, however, and dermal exposures would also drive the unreasonable risk due to non-cancer effects (specifically liver toxicity).
EPA notes that the November 2020 risk evaluation contained a typographical error in the acute dermal point of departure (POD). EPA corrected this error in a July 2022 errata memorandum posted to docket EPA-HQ-OPPT-2019-0499. EPA states that the changes to the risk estimates for acute dermal exposures are reflected in the draft revision to the risk determination. According to EPA, the corrections do not alter the COUs that drive the unreasonable risk determination for carbon tetrachloride.
EPA states that two out of the 15 COUs do not drive the unreasonable risk: when carbon tetrachloride is processed as a reactant in reactive ion etching and in distribution in commerce. EPA is not proposing to make COU-specific risk determinations for those COUs or to issue an order under TSCA Section 6(i)(1), however.
EPA states that following the final revised risk determination for carbon tetrachloride, consistent with the statutory requirements of TSCA Section 6(a), it will propose risk management regulatory action to the extent necessary so that carbon tetrachloride no longer presents an unreasonable risk. EPA expects to focus its risk management action on the COUs that drive the unreasonable risk. EPA notes that under TSCA Section 6(a), it is not limited to regulating the specific activities found to drive unreasonable risk and may select from among a suite of risk management requirements in Section 6(a) related to manufacture (including import), processing, distribution in commerce, commercial use, and disposal as part of its regulatory options to address the unreasonable risk. As a general example, EPA may regulate upstream activities (e.g., processing, distribution in commerce) to address downstream activities (e.g., consumer uses) driving unreasonable risk, even if the upstream activities do not drive the unreasonable risk.
Separately, EPA is conducting a screening approach to assess potential risks from the air and water pathways for several of the “first 10” chemicals, including carbon tetrachloride. For carbon tetrachloride, the exposure pathways that were or could be regulated under another EPA-administered statute were excluded from the 2020 risk evaluation. According to EPA, this resulted in the ambient air and ambient/drinking water pathways not being assessed. EPA states that its screening approach will identify if there are risks that were unaccounted for in the risk evaluation for carbon tetrachloride. While this analysis is underway, EPA is not incorporating the screening-level approach into this draft revised unreasonable risk determination. If the results suggest there is additional risk, EPA will determine if the risk management approach being contemplated for carbon tetrachloride will protect against these risks or if the risk evaluation will need to be supplemented formally or revised.
As reported in our July 12, 2022, memorandum on the draft revisions to the risk determinations for perchloroethylene (PCE), N-methylpyrrolidone (NMP), methylene chloride (MC), and trichloroethylene (TCE), and in our July 21, 2022, memorandum on the draft revisions to the risk determination for 1-bromopropane (1-BP), Bergeson & Campbell, P.C. (B&C®) identified several common issues that EPA did not address as comprehensively as it might. Specifically, in each evaluation, EPA is using a systematic review method that fails to meet the scientific standards under TSCA Section 26, and as a result, EPA made a whole chemical risk determination that conflicts with 40 C.F.R. Subpart B, and in making a baseline assumption of the absence of PPE, EPA made a decision that many believe ignores reasonably available information, in violation of TSCA. These same deficiencies are common to the draft revised risk determination for carbon tetrachloride and the underlying final risk evaluation. We have focused the following discussion on several observations based on our review of the final risk evaluation on carbon tetrachloride, including EPA’s pragmatic approach for evaluating de minimis consumer exposures.
Perhaps the most controversial aspect of the Final Risk Evaluation for Carbon Tetrachloride is EPA’s use of a linear low-dose extrapolation to quantify cancer risks based on adrenal tumors in male mice from a two-year cancer study. EPA used the linear low-dose extrapolation because of the absence of a fully elucidated mode of action for these tumors. In comparison, when the TSCA Science Advisory Committee on Chemicals (SACC) reviewed the draft Risk Evaluation for Carbon Tetrachloride, it recommended that “EPA should apply a non-linear model in estimating cancer risks, in light of the preponderance of evidence that [cellular toxicity, not mutagenicity is] the origins of tumors of the liver and adrenal gland.” This is an important point given that disregarding the SACC’s recommendations may serve as a potential “red flag” if the final risk management rule is challenged in court.
B&C is pleased to see EPA’s justification for not evaluating consumer exposures. EPA noted in the draft revised risk determination that the U.S. Consumer Product Safety Commission (CPSC) “banned the use of carbon tetrachloride in consumer products (excluding unavoidable residues not exceeding 10 ppm atmospheric concentration) in 1970.” EPA went on to state that it “expects that consumer use of [products that contain carbon tetrachloride as an impurity] present only negligible exposure to carbon tetrachloride…” B&C agrees with this pragmatic approach, but we are perplexed that EPA did this given EPA’s views on similar issues with new chemicals, as discussed below.
First, it is not clear why EPA assumes compliance with the CPSC’s ban on carbon tetrachloride in consumer products when EPA simultaneously assumes non-compliance with OSHA’s standards. In B&C’s view, non-compliance with either standard would be misuse, a characterization Congress specifically stated was not within the meaning of “reasonably foreseen” COU.
Second, EPA concluded that “consumer uses of carbon tetrachloride in commercially available aerosol and non-aerosol adhesives and sealants, paints and coatings, and cleaning and degreasing solvent products would present only de minimis exposures or otherwise insignificant risks and did not warrant further evaluation or inclusion in the risk evaluation.” While B&C agrees with EPA’s conclusion, this stance conflicts with EPA’s recent announcement that it will calculate risks from all exposures, regardless of how low they might be. More information on EPA’s policy to discontinue the use of exposure modeling thresholds when assessing the health and environmental risks of new chemicals under TSCA is available in our August 22, 2022, memorandum.
In addition to these issues, we note that the Office of Pollution Prevention and Toxics (OPPT) received a request for correction (RFC) of information on the Final Risk Evaluation for Carbon Tetrachloride on January 26, 2021. As of the date of this memorandum, OPPT has not provided a response to the RFC. It is not clear why EPA did not account for the RFC as part of its review of the risk evaluation and EPA provides no explanation. It implies that EPA’s intent with this update was limited to updating its conclusion about unreasonable risk regardless of the potential flaws in its analysis.
B&C encourages interested parties to review the revised draft risk determination on carbon tetrachloride, and the other recent revised draft risk determinations (e.g., PCE, NMP, MC, TCE, and 1-BP). These documents contain common issues that raise questions as to whether EPA has satisfied its legal requirements under TSCA with regard to using the best available science and weight of scientific evidence. B&C suggests commenting on common issues whenever EPA solicits comments. Doing so maximizes the opportunity to place issues on the record, should future challenges be required on the pending risk management rules. We mention this because of the importance of building an administrative record in the event that judicial challenge becomes necessary on a final risk management rule, a possibility that B&C views as a near certainty, given the novelty of the statute and precedents that the final rules will set.