The U.S. Environmental Protection Agency (EPA) announced on July 25, 2024, that it is proposing to designate acetaldehyde, acrylonitrile, benzenamine, vinyl chloride, and 4,4-methylene bis(2-chloroaniline) (MBOCA) as high-priority substances (HPS) for risk evaluation under the Toxic Substances Control Act (TSCA). 89 Fed. Reg. 60420. EPA is providing a 90-day comment period, during which interested persons may submit comments on the proposed designations of these chemicals as HPSs for risk evaluation. EPA states that it is interested in comments that would inform the exposure and hazard assessments and the identification of conditions of use (COU) for these chemicals. Comments are due October 23, 2024.

Background

As reported in our December 27, 2023, memorandum, in December 2023, EPA began the process to prioritize these five chemicals for risk evaluation. EPA requested relevant information for each, including but not limited to, the chemical’s hazard and exposure potential; the chemical’s persistence and bioaccumulation; potentially exposed or susceptible subpopulations relevant to the prioritization; whether there is any storage of the chemical near significant sources of drinking water; the chemical’s COUs or significant changes in COUs, including information regarding trade names; the chemical’s production volume or significant changes in production volume; and any other information relevant to the potential risks of the chemical that might be relevant to the designation of the chemical’s priority for risk evaluation.

Information and Comments Received

EPA states that it received more than 9,000 submissions from commenters, including private citizens, potentially affected businesses, trade associations, Tribes, environmental and public health advocacy groups, and academia. According to EPA, comments addressed the overall prioritization process (e.g., the collection and consideration of relevant information); the review process (e.g., the use of data and approaches in risk evaluation); information specific to the candidate chemicals (e.g., relevant studies, assessments, and COUs); and topics not germane to this prioritization process (e.g., scheduling future chemicals for prioritization and concerns about risk evaluation fees). To the extent that comments provided information on additional COUs for these candidate HPSs, EPA states that those COUs are discussed in the proposed designation documents for each chemical. EPA notes that it will respond to those and any additional comments on the proposed designations when it issues the final priority designation of these chemicals.

Information, Analysis, and Basis Used to Support the Proposed High-Priority Substance Designations

EPA states that it used reasonably available information, including public comments received during the 90-day comment period following initiation of the prioritization process, to analyze the candidate chemicals against the criteria and considerations in TSCA Section 6(b)(1)(A) and 40 C.F.R. Section 702.9. EPA developed a proposed designation document for each chemical that identifies the information, analysis, and basis used to support the proposed designation of each as an HPS for risk evaluation. EPA developed a systematic review support document entitled “Updated Search Strategies Used to Identify Potentially Relevant Discipline-Specific Information” to explain further how potentially relevant data sources for various disciplines (e.g., physical and chemical properties, occupational exposure and environmental release, environmental and human health hazard), are identified from the larger set of data sources identified for each of the chemicals currently being proposed as an HPS for risk evaluation. EPA notes that these documents are available in the docket for each chemical. Each document also includes an explanation of the approach EPA used to conduct the review, as well as an overview of the requirements in TSCA Section 6(b)(1)(A) and the regulatory section addressing the following review criteria and considerations (40 C.F.R. Section 702.9).

Production Volume or Significant Changes in Production Volume

EPA states that it considered the reasonably available information on the current production volume or significant changes in production volume of the chemical. According to EPA, it primarily used reported information from manufacturers (including importers) under the Chemical Data Reporting (CDR) rule (40 C.F.R. Part 711). EPA assembled information reported from 1986 through 2020 on the production volume under the Inventory Update Rule (IUR) and CDR. The most recent principal reporting year for which CDR data are available is 2019, for which information was reported in 2020.

COUs or Significant Changes in COUs

EPA considered the reasonably available information on COUs or significant changes in COUs of the chemicals. TSCA Section 3(4) defines the term “conditions of use” to mean the circumstances, as determined by the Administrator, under which a chemical is intended, known, or reasonably foreseen to be manufactured, processed, distributed in commerce, used, or disposed of. EPA states that it assembled information submitted by manufacturers (including importers) during the 2016 and 2020 CDR reporting cycles. Based on the manufacturing information, industrial processing and use information, consumer and commercial use information reported under CDR during the 2016 and 2020 reporting cycles, EPA developed a list of COUs. In addition, EPA reviewed uses from other publicly available data sources such as the Toxics Release Inventory (TRI), Discharge Monitoring Reports (DMR), National Emissions Inventory (NEI), Safety Data Sheets (SDS), Chemical Exposure Knowledgebase (ChemExpo), High Priority Chemicals Data System (HPCDS), chemical-specific information received from public commenters, and chemical-specific information from EPA’s screening review of the reasonably available information for each chemical. EPA notes that should it make a final decision to designate a chemical as an HPS for risk evaluation, it will identify further characterization of relevant TSCA COUs during the risk evaluation process as part of its scope document.

Potentially Exposed or Susceptible Subpopulations

EPA considered reasonably available information to identify potentially exposed or susceptible subpopulations. At this stage, EPA analyzed information about children, women of reproductive age, consumers, workers, and overburdened communities for the following scenarios:

• For children, EPA screened for each chemical’s use in products and articles regulated under TSCA and intended for children, using CDR information reported during the 2016 and 2020 CDR cycles. EPA presented information regarding those commercial and consumer uses when the chemical was identified as being used in products intended for children and also indicated if use in children’s products was identified in the HPCDS. Additionally, EPA identified the potential for developmental hazards resulting from exposure to the chemical that may affect children;
• For women of reproductive age, EPA screened against the exposure and hazard information for the chemical that characterized potential for reproductive and/or developmental effects following exposure to the chemical;
• For consumers, EPA characterized the potential for consumer exposure based on consumer uses reported to CDR during the 2016 and 2020 reporting cycles, and reported consumer uses in the Chemical and Products database (CPDat), HPCDS, and public comments;
• For workers, EPA characterized the potential for occupational exposures to workers based on the COUs of each chemical; and
• For overburdened communities, EPA described the considerations for overburdened communities that may experience disproportionate environmental harms, risks, or multiple burdens from chemical exposure.

Persistence and Bioaccumulation

EPA states that it considered reasonably available information of the chemical and assessed physical and chemical properties used to determine persistence and bioaccumulation based on the best available science. In the proposed designation documents, EPA presents a summary of the physical, chemical, environmental fate, and transport properties of each chemical.

Storage Near Significant Sources of Drinking Water

EPA notes that TSCA Section 6(b)(1)(A) specifically requires the Agency to consider the chemical’s storage near significant sources of drinking water. EPA states that it reviewed reasonably available information, including certain existing regulations or protections in place for the proposed chemicals, such as existing National Primary Drinking Water Regulations (40 C.F.R. Part 141) and other regulations under the Clean Water Act (CWA) (40 C.F.R. Section 401.15). In addition, EPA considered the consolidated list of chemicals subject to reporting requirements under Sections 302 and 313 of the Emergency Planning and Community Right-to-Know Act (EPCRA), Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), and the Clean Air Act (CAA) (Section 112) (Regulated Chemicals for Accidental Release Prevention). According to EPA, “[r]egulation under one or more of these authorities is an indication that a substance is a potential health or environmental hazard, which, if released near a significant source of drinking water, may present unreasonable risk to health or the environment.” To identify storage of chemicals near significant sources of drinking water, EPA also identified facilities reporting the chemicals to the TRI in 2022 near potential sources of drinking water using public water systems data stored in EPA’s Safe Drinking Water Information System Federal Data Warehouse. EPA determined whether TRI reporting facilities are located inside defined Source Water Protection Areas or within four miles of wellheads to identify potential storage of each chemical near sources of surface water and groundwater, respectively.

Hazard Potential

EPA considered reasonably available information to identify the potential hazards for each chemical. EPA surveyed information from previous assessments and databases and summarized the reasonably available information for potential human health and environmental hazards by endpoints of concern.

Exposure Potential

EPA considered reasonably available information to identify potential environmental, worker/occupational, consumer, and general population exposure for each chemical for the following scenarios:

• For environmental exposure, EPA considered the COUs and activities associated with those COUs and considered environmental monitoring data and fate properties of each chemical to anticipate its presence in different environmental media;
• For worker/occupational exposure, EPA identified the COUs likely to result in workers being exposed to the chemical, such as manufacturing, processing, industrial and commercial use, distribution in commerce, and disposal;
• For consumer exposure, EPA considered consumer uses using CDR information and information from CPDat. Additionally, EPA considered the potential use in children’s products from the HPCDS and through public comments; and
• For general population exposure, EPA considered releases from certain COUs as reported in TRI, such as manufacturing, that may result in general population exposure via pathways and routes such as drinking water ingestion and/or inhalation from releases to the atmosphere.

Other Risk-Based Criteria EPA Determined to Be Relevant to the Designation of the Chemical

EPA states that it did not identify other risk-based criteria relevant to the proposed designations of the candidate chemicals as HPSs for risk evaluation.

Commentary

Bergeson & Campbell, P.C. (B&C^®) is not surprised that EPA proposed to designate these substances as HPSs for risk evaluation. We are, however, surprised by EPA’s proposed designation documents on the proposed HPSs. These documents appear to be lacking relevant information that would otherwise aid with EPA’s final HPS determinations. We discuss a few issues we identified using acetaldehyde as an example. We then discuss what entities should be mindful of if and when EPA identifies these five chemical substances as HPSs.

EPA used the systematic review process from its document titled “Draft Systematic Review Protocol Supporting TSCA Risk Evaluations for Chemical Substance” (2021 Draft SR Document) to identify relevant information on the proposed HPSs, per the criteria and considerations stated under 40 C.F.R. Section 702.9. EPA supplemented the 2021 Draft SR Document with its newly released systematic review support document for each of the proposed HPSs titled “Updated Search Strategies Used to Identify Potentially Relevant Discipline-Specific Information” (2024 Updated Strategy). EPA issued the 2024 Updated Strategy “Based upon recommendations by the Scientific Advisory Committee on Chemicals regarding the 2021 Draft [SR Document] … Specifically, EPA has incorporated additional data sources such as assessments published by other government agencies to identify potential hazards and exposures ….”

We agree with EPA’s inclusion of assessments published by other governmental agencies. EPA’s list of other government agencies was, however, incomplete and did not include relevant and more recent findings from these agencies. For example, EPA listed various findings from Environment Canada and Health Canada (EC/HC) (2000), the former National Industrial Chemicals Notification and Assessment Scheme (NICNAS) (2019) [which changed to the Australian Industrial Chemicals Introduction Scheme (AICIS) in 2020], and several other agencies in its document titled “Proposed Designation of Acetaldehyde as a High-Priority Substance for Risk Evaluation” (AA Proposed Designation). EPA did not mention key conclusions from the cited sources and did not cite more recent documents from the same agencies that provided relevant information for informing EPA’s final HPS designations. Examples of the excluded information include the following.

• EPA referenced EC/HC (2000) as a source for informing that acetaldehyde “may be present in ambient air, surface water, and soil,” “is not expected to bioaccumulate in aquatic species” in soil, and that it “is not expected to adsorb to soil particles and would be considered mobile in the soil.” EPA did not reference Health Canada’s 2017 conclusions that “The weight of evidence points to a non-linear (or threshold) mode of action (MOA) for acetaldehyde carcinogenesis.”
• EPA referenced the carcinogenicity classification from NICNAS (2019) that found acetaldehyde is “suspected of causing cancer.” EPA did not mention that NICNAS also concluded that “Based on the weight of evidence of the available data, a threshold-based mechanism of carcinogenicity for acetaldehyde is likely following inhalation exposure.”
• EPA referenced the U.S. Food and Drug Administration’s (FDA) 1991 “Total Diet Study.” EPA did not mention FDA’s 2023 conclusion that “the weight of evidence [supports] a nonlinear dose response for the carcinogenicity of acetaldehyde following oral administration ….”

The above issues are concerning because this is not the first time that EPA has not considered the scientific evaluations from assessments issued by other government agencies when those assessments conflict with EPA’s evaluations. For discussion, see our memorandum dated July 31, 2023.

EPA stated in the AA Proposed Designation that it “did not identify other risk-based criteria relevant to the proposed designation of acetaldehyde under TSCA.” Based on the conclusions of other government agencies (e.g., Health Canada, NICNAS, and FDA) that acetaldehyde is a threshold carcinogen, we question why EPA did not consider this relevant as a risk-based criterion, given that using a linear (i.e., no threshold) low-dose extrapolation versus a non-linear (i.e., threshold) extrapolation has a profound impact on carcinogenic risk assessments and subsequent conclusions about risk. We realize that EPA may not agree with the conclusions of other government agencies, but these conclusions should be stated in EPA’s proposed designation. A non-threshold approach is the default for chemical substances that are mutagenic carcinogens or carcinogens without an elucidated MOA. In comparison, a threshold approach is appropriate for non-mutagenic carcinogens with an elucidated MOA, a determination that requires more robust data. It is unclear if EPA’s oversight of the above-referenced information was due to limitations with its systematic review process, its disagreement with the threshold conclusions made by other agencies, or EPA’s preference with applying a linear low-dose extrapolation. After all, EPA used a linear low-dose extrapolation in its 2024 draft risk evaluation for formaldehyde, despite the World Health Organization’s (WHO) 2010 conclusion that “a threshold approach to setting a guideline for cancer effects is appropriate” and the French Agency for Food, Environmental and Occupational Health & Safety’s (ANSES) 2019 conclusion that “the carcinogenic mode of action of formaldehyde relies on a serie [sic] of key events above a threshold.” EPA is allowed to disagree with other competent authorities, but EPA should have a well-reasoned and articulated basis for doing so. Omitting or ignoring the conclusions of other competent authorities can lead to the appearance of outcome-determinative data selection — a violation of EPA’s scientific integrity policy. It is likely that EPA could justify designating acetaldehyde as an HPS even when considering the scientific disagreement, but without EPA’s thoughtful consideration of all of the facts, a reader is left to speculate.

B&C expects EPA to designate the five chemical substances as HPSs, and manufacturers (including importers) should be mindful of the potential financial obligations triggered by EPA’s final HPS designations. These obligations include EPA’s assessment of fees on manufacturers (including importers) of $4,287,000 for non-small businesses and $857,400 for small businesses, according to a cost-sharing formula established by EPA, unless one of the two following conditions is met:

• The manufacturer (including importer) had already ceased manufacturing prior to the defined cutoff dates and will not manufacture (including import) for five years; or
• The manufacturer (including importer) has not manufactured the chemical substance in the five-year period preceding publication of the preliminary lists.

The above fees are in addition to expenses that manufacturers will incur once EPA issues in final its proposed TSCA Section 8(d) rule on 16 chemical substances, including the five proposed HPSs, requiring the submission of certain unpublished health and safety studies. For discussion, see our commentary dated April 5, 2024. Additional costs may be incurred if, for example, EPA determines that any data gap exists that warrants the issuance of TSCA Section 4 test orders. This is unlikely for the five proposed HPSs because EPA stated that “data availability was a significant driver of the Agency’s selections” when it initiated prioritization on these substances in December 2023.

These expenses address the required fees for prioritization (stage 1) and risk evaluation (stage 2) as part of EPA’s three-stage process for assessing chemical substances under TSCA Section 6. EPA’s eventual risk management (stage 3) on these substances will impose additional financial obligations once risk management rules are issued in final.