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May 14, 2024

EPA Amends Procedural Framework Rule for Conducting TSCA Risk Evaluations

The ACTA Group

The U.S. Environmental Protection Agency (EPA) released a final rule on April 23, 2024, that amends the procedural framework rule for conducting risk evaluations under the Toxic Substances Control Act (TSCA). According to the final rule, published in the Federal Register on May 3, 2024, EPA reconsidered the procedural framework rule for conducting such risk evaluations and is revising certain aspects of that framework to align better with the statutory text and applicable court decisions, to reflect its experience implementing the risk evaluation program following enactment of the 2016 TSCA amendments, and to allow for consideration of future scientific advances in the risk evaluation process without the need to amend further the Agency’s procedural rule. 89 Fed. Reg. 37028. The final rule will take effect July 2, 2024.

General Provisions

EPA is amending the general provisions at 40 C.F.R. Section 702.31 as proposed. The procedures will apply to all risk evaluations initiated 30 days after the date of the final rule or later. For manufacturer-requested risk evaluations (MRRE) in process as of the date of the final rule, EPA expects to apply the proposed changes to those risk evaluations “only to the extent practicable, taking into consideration the statutory requirements and deadlines.”

EPA states that the final rule includes the minor clarification with respect to the applicability of the rule to risk evaluations on categories of chemical substances in 40 C.F.R. Section 702.31(d). EPA notes that the rule does not prescribe how or whether it will identify categories appropriate for prioritization and risk evaluation. The criteria for establishing categories are specified in TSCA Section 26(c). According to the final rule, if EPA does categorize chemicals as a category, it will provide, on a case-by-case basis, the justification for inclusion of the chemicals in a category.

Technical Corrections and Reorganization

The proposed rule reflects a number of minor updates and corrections and general organizational restructuring. EPA states that it aimed to improve the readability of certain provisions, and, ultimately, enhance the public’s ability to understand how EPA will undertake TSCA risk evaluations. EPA reorganized the sequence and structure of regulatory provisions to establish sections that distinguish between the components of the risk evaluation, the analytic considerations to be applied in the risk evaluation, and the associated procedural timeframes and actions. EPA carried these changes through into the final rule.


The final rule makes minor updates to definitions for “pathways,” “routes,” “aggregate exposure,” and “sentinel exposure.” The final rule also maintains the definitions for “act,” “conditions of use” (COU), “reasonably available information,” “uncertainty,” or “variability” — “all unchanged from the 2017 final rule.” EPA proposed to eliminate the codified definitions for “best available science” and “weight of scientific evidence.” According to the final rule, EPA “can say with confidence that the Agency is fully committed to meeting the requirements in the law, and to being transparent in each risk evaluation with respect to how scientific information, technical procedures, measures, methods, protocols, methodologies, or models are being employed in a manner consistent with the best available science and how decisions are based on the weight of the scientific evidence, as required by 15 U.S.C. 2625(h) and (i).” As such, the final rule removes these definitions from the codified regulatory text.

EPA also proposed changes to the definition of “potentially exposed or susceptible subpopulation” (PESS), which currently includes “infants, children, pregnant women, workers or the elderly.” Namely, EPA states, it proposed to add the phrase “overburdened communities” to the list of other examples of PESS that EPA might identify like “infants, children, pregnant women, workers, or the elderly.” After considering the comments, EPA determined to amend the PESS definition as proposed.

Scope of TSCA Risk Evaluations

Inclusion of All COUs

EPA states that it proposed a number of changes to the regulatory text to make clear that the scope of TSCA risk evaluations will not exclude any COUs. EPA states that it has some discretion; “the identification of a chemical’s conditions of use falls squarely within EPA’s purview and will necessarily involve the Agency applying both fact and professional judgment, particularly with respect to identifying whether a circumstance is reasonably foreseen.” EPA notes that it “also has discretion in tailoring its level of analysis with respect to individual conditions of use within the scope of the risk evaluation and may choose to, for example, take a more qualitative approach to conditions of use that it determines are negligible contributors to exposures and risks based on the reasonable available information.” According to the final rule, EPA does not view the statute as providing authority to exclude categorically known COUs or exposures from the scope of the risk evaluation entirely, however.

Determination of COUs

EPA distinguishes between its lack of discretion to exclude COUs as described in the previous section and its ability to exercise judgment in making its determination as to whether a particular circumstance is intended, known, or reasonably foreseen, and therefore falls within the definition of COU for a particular chemical. EPA states that for each risk evaluation, and consistent with the phrase “as determined by the Administrator” in the statutory definition of COUs, “EPA must analyze the reasonably available information and apply the facts, Agency expertise and professional judgment to determine that chemical’s conditions of use.” According to EPA, the determination of whether a particular circumstance is reasonably foreseen — and therefore an exposure that must be considered within the scope of the risk evaluation — “is necessarily going to require a fact-specific, chemical-by-chemical analysis.” EPA notes that ultimately, its determination on the chemical’s COUs and the rationale to support those conclusions will be subject to public review and comment as part of each risk evaluation.

Inclusion of All Exposure Pathways

EPA states that it concludes that the best interpretation of TSCA is that the law does not authorize the exclusion of relevant exposure pathways from consideration in a risk evaluation. EPA notes that certain risk evaluations published during the prior Administration were challenged, including on the grounds that EPA’s prior approach of excluding exposure pathways was inconsistent with TSCA requirements. According to EPA, the approach adopted in the final rule “may conserve judicial, EPA, and other federal government resources by avoiding or reducing the need for such litigation. In addition, EPA has discretion to carry out TSCA risk evaluations in a fit-for-purpose manner, tailoring the depth or extent of analysis commensurate with the nature and significance of the decision, and expects to employ these approaches to enable completion of risk evaluations within the statutory deadlines.”

Comprehensive but Fit-for-Purpose

As noted in the proposed rule, EPA “does not believe risk evaluations under TSCA should be so complex or procedurally cumbersome that they cannot reliably be completed within the timeframes required by the statute.” EPA states that at the same time, it cannot produce partial or incomplete TSCA risk evaluations or pursue risk evaluations in a manner that is otherwise incompatible with the statutory framework. EPA “appreciates the suggestion” that it develop guidance for how it might apply fit-for-purpose approaches in different circumstances. According to the final rule, EPA believes that fit-for-purpose approaches in risk evaluations are an essential part of implementing the TSCA program and sustaining it over the long-term.

Additional Efficiencies

EPA states that it will continue to abide by the statutory requirement to publish the final scope within the first six months after initiation of a risk evaluation. EPA has already been maintaining the practice of publishing a preliminary list of COUs during the Proposed Designation step of the prioritization process, as some commenters suggest. EPA sees additional value in publishing more robust preliminary information on the COUs, hazards, exposures, and PESS that it expects to consider, and any early indications as to how it may apply fit-for-purpose approaches, however. EPA notes that public comments received on this information can inform the final priority designation and, if the chemical is then designated as a high-priority substance, the scope of the risk evaluation.

Risk Determinations

Single Determination on the “Chemical Substance”

EPA states that it agrees that TSCA requires consideration of the chemical’s COUs and that the potentially different exposure scenarios presented by different COUs should be reflected in the risk evaluation’s exposure assessment. According to EPA, “the plain language of the law requires EPA to determine whether the chemical substance, rather than individual conditions of use, presents an unreasonable risk,” however. EPA notes that in addition to aligning its process with the statutory text and structure, this approach ensures that it is best positioned to incorporate reasonably available information, make determinations consistent with the best available science and based on the weight of scientific evidence, including, where appropriate, risk determinations that consider aggregate exposure resulting from multiple COUs. The final rule will amend the regulatory text to ensure risk evaluations will always culminate in a single risk determination on the “chemical substance,” including the language in 40 C.F.R. Sections 702.37(a)(5) and 702.39(f)(1).

Risk Communication Related to Single Risk Determination

EPA states that it appreciates the concerns regarding clear risk communication as part of each risk determination but disagrees with the suggestion that the single risk determination approach will lead to a finding of unreasonable risk in every instance. EPA “is strengthening its commitment” in the final rule to identify which COUs are significant contributors to the unreasonable risk by changing the text to indicate a more affirmative “will identify” from the proposed “intends to” and by moving the regulatory text directly into the section on the “Unreasonable Risk Determination” at 40 C.F.R. Section 702.39(f). According to EPA, “[w]hile not necessarily a perfect indicator of how EPA will ultimately regulate to address unreasonable risk, this communication should give industry stakeholders significant insight and more certainty.” EPA notes that in addition to providing a rationale and explanation in the risk determination itself, it is further committed to communicating clearly on its analysis of particular uses in other venues, “and will refrain from making unqualified statements about the risk associated with the chemical substance that could generate the type of confusion commenters are concerned about.”

Regulatory Approaches Based on Single Risk Determination

According to EPA, several commenters suggested that it use a singular risk determination “to regulate in an overly broad manner, creating unnecessary and duplicative requirements, and shifting the burden to industry to demonstrate that they should not be regulated.” EPA notes that an unreasonable risk determination does not mean that EPA will regulate all COUs for that chemical, and “EPA disagrees with commenters’ suggestion to the contrary.” EPA states that the determination itself has no bearing on which COUs will be the focus during the risk management phase. EPA’s statutory authority to regulate chemicals under TSCA Section 6 is available only “‘to the extent necessary so that the chemical substance or mixture no longer presents [unreasonable] risk.’ (15 U.S.C. 2605(a)).”

EPA notes that it “also strongly disagrees that a single risk determination on the chemical substance would be unscientific or arbitrary.” According to EPA, its basic methodological approach to risk assessments is unchanged in the final rule. EPA states that for every chemical, it will, “using the best available science and based on the weight of scientific evidence, conduct a hazard assessment, conduct an exposure assessment based on the chemical’s conditions of use, characterize the risks, propose a determination as to whether the risk is unreasonable under TSCA, and conduct a transparent and independent scientific peer review with opportunities for public comment.”

Preemption of State Laws/Regulations

According to EPA, the scope of permanent preemption is the same under either a single risk determination for the chemical substance or the use-based approach previously applied. Consequently, while EPA disagrees with commenters’ reading of TSCA with respect to the requirement for a single risk determination on the chemical substance, EPA agrees that Congress intended permanent preemption to apply to COUs EPA addresses in the risk evaluation. EPA states that it has concluded that the chemical-based approach to risk determination is required under a plain reading of the statutory text and structure and consistent with Congressional intent. EPA further notes that the plain language in TSCA Section 18 also supports the view that Congress intended EPA to make a single risk determination on the chemical substance, “namely, the numerous references to ‘chemical substance’ as opposed to uses of a chemical substance, and ‘determination’ in the singular.”

“Unreasonable Risk” Considerations

EPA states that neither TSCA nor the final rule define “unreasonable risk” “given the inherently unique nature of each risk evaluation and the need for EPA to make this determination on a case-by-case basis.” The proposed rule includes a discussion of considerations EPA may weigh in determining unreasonable risk, including, but not limited to: the effects of the chemical substance on health and human exposure to such substance under the COUs (including cancer and noncancer risks); the effects of the chemical substance on the environment and environmental exposure under the COUs; and the population exposed (including any PESS), the severity of hazard (the nature of the hazard, the irreversibility of hazard), and uncertainties. According to EPA, it did not receive significant comments on this topic and is amending the rule as proposed.

Risk Evaluation Considerations

Occupational Exposure Assumptions

The final rule includes new regulatory text at 40 C.F.R. Section 702.39(f)(2) to ensure that “consideration of occupational exposure scenarios will take into account reasonably available information” and that EPA will “not consider exposure reduction based on assumed use of personal protective equipment [(PPE)] as part of the risk determination.” EPA states that it believes that the assumed use of PPE in a risk determination could lead to an underestimation of the risk to workers. Where information on known occupational control measures is made available, however, EPA “is committed to taking that information into account in the exposure assessment.” According to EPA, it has been consistent in urging industry to provide information regarding worker exposure controls. EPA notes that it considers information from the risk evaluation’s exposure assessment in risk management action and that the information can be useful in facilitating consistency with broader industry best practices where possible. EPA “encourages commenters to continue engaging with EPA on this point on chemical-specific actions and to provide the Agency with timely and relevant data that can be considered during the TSCA process.”

Aggregate Exposure

EPA states that the proposed rule includes regulatory text committing it to consider aggregate exposures as part of TSCA risk evaluations and, when supported by reasonably available information, consistent with the best available science and based on the weight of scientific evidence, to include an aggregate exposure assessment in the risk evaluation, or otherwise explain the basis for not doing so. EPA also proposed minor revisions to the definition of “aggregate exposure.” After considering public comments on this issue, EPA is adopting the new regulatory text as proposed.

Cumulative Risk

EPA notes that although it did not propose any regulatory changes regarding consideration of cumulative risk, advancing the science of cumulative risk is a high priority to inform EPA’s effort to understand better and mitigate risks to PESS. After considering comments, EPA is issuing a final rule without an explicit requirement related to cumulative risk assessment. EPA states that it is “nonetheless committed to considering and applying cumulative risk assessment approaches for future chemicals undergoing risk evaluation, where supported by the reasonably available information and best available science.”


TSCA requires EPA to evaluate risk to PESS identified as relevant to the risk evaluation by the Administrator, under the COUs. TSCA defines PESS as “a group of individuals within the general population identified by the EPA who, due to either greater susceptibility or greater exposure, may be at greater risk than the general population of adverse health effects from exposure to a chemical substance or mixture, such as infants, children, pregnant women, workers, or the elderly.” EPA proposed to amend the definition by adding the term “overburdened communities” to the list of example subpopulations, reflecting EPA’s “understanding and acknowledgment that a chemical substance may disproportionately expose and/or may disproportionately impact communities already experiencing disproportionate and adverse human health or environmental burdens.” EPA is amending the PESS definition as proposed to reflect better its commitment to consider fully the impacts a chemical undergoing TSCA risk evaluation may present to communities already experiencing disproportionate and adverse human health or environmental burdens.

Risk-Based Occupational Exposure Values

As part of the proposed rule, EPA requested comment on how to improve the transparency of any risk-based occupational exposure values derived from the risk evaluation process. Although occupational exposure values for some of EPA’s first ten chemicals came out at a different time than the risk evaluations themselves, EPA states that it does not intend this to be the practice moving forward. The final rule includes a commitment in the regulatory text to calculate a risk-based occupational exposure value in the draft risk evaluation where EPA identifies unreasonable risk to workers through inhalation. As part of this commitment, EPA will explain in each risk evaluation how the value was calculated.

According to the final rule, to avoid confusion, EPA “is no longer referring to the risk-based occupational exposure value calculated in the risk evaluation as an Existing Chemical Exposure Limit (ECEL).” EPA will base the risk-based occupational exposure value calculated in the risk evaluation on the most sensitive hazard endpoint and standard occupational exposure scenarios assumption, and by law, cannot consider costs or other non-risk factors. EPA notes that the value is not a regulatory limit or level, though it can be used to inform risk management.

Scientific Guidance and Procedures

In General

EPA codified the use of appropriate Agency guidance (which EPA states can also include Agency guidelines, frameworks, handbooks, or standard operating procedures) in the development of risk evaluations in the 2017 final rule and proposed to maintain that regulatory text. According to EPA, it  received support from public commenters on this provision and is codifying it as proposed.

Peer Review

In the proposed rule, EPA proposed to amend the text on peer review to clarify the Agency’s flexibility in determining how and what to peer review. The proposed regulatory text read: “EPA expects that peer review activities on risk evaluations conducted pursuant to 15 U.S.C. 2605(b)(4)(A), or portions thereof will be consistent with the applicable peer review policies, procedures, guidance documents, and methods pursuant to guidance promulgated by Office of Management and Budget [(OMB)], EPA, and in accordance with 15 U.S.C. 2625(h) and (i).” In the final rule, EPA has amended the proposed text to affirm that EPA will conduct peer review: “EPA will conduct peer review activities on risk evaluations…” With respect to EPA’s use of “or portions thereof” in the proposed text, EPA states that it did not intend that phrase to reflect a policy change, but rather to clarify the allowable scope of peer review under both the EPA Peer Review Handbook 4th Edition 2015 (EPA Handbook) and OMB’s Information Quality Bulletin for Peer Review (Peer Review Bulletin). After considering the comments, EPA has removed the “or portions thereof” language, stating that it was “an unnecessary codification of a practice that is already allowed under existing guidance documents.” EPA notes that the final rule makes clear “that EPA will conduct peer review activities on TSCA risk evaluations, and expects those activities and related decisions regarding the appropriate scope and type of peer review to be consistent with the applicable guidances from OMB and EPA.”

Scientific Standards

Best Available Science

According to EPA, use of best available science involves the use of supporting studies conducted in accordance with sound and objective science practices, including, when available, peer reviewed science and supporting studies and data collected by accepted methods or best available methods (if the reliability of the method and the nature of the decision justifies use of the data). EPA states that it does not believe codifying a definition of “best available science” provides any additional transparency or improves consistency, as for each risk evaluation, EPA must determine what is the best available science based on the reasonably available information. The final rule requires EPA to “document that the TSCA risk evaluation is consistent with the best available science and based on the weight of the scientific evidence” in 40 C.F.R. Section 702.37(a). With respect to “best available science,” EPA is also codifying the list of considerations for determining what constitutes the best available science — considerations that it notes are taken directly from TSCA Section 26(h):

(1)        The extent to which the scientific information, technical procedures, measures, methods, protocols, methodologies, or models employed to generate the information are reasonable for and consistent with the intended use of the information;

(2)        The extent to which the information is relevant for the Administrator’s use in making a decision about a chemical substance or mixture;

(3)        The degree of clarity and completeness with which the data, assumptions, methods, quality assurance, and analyses employed to generate the information are documented;

(4)        The extent to which the variability and uncertainty in the information, or in the procedures, measures, methods, protocols, methodologies, or models, are evaluated and characterized; and

(5)        The extent of independent verification or peer review of the information or of the procedures, measures, methods, protocols, methodologies or models.

Systematic Review and Fit-for-Purpose Approaches

The final rule eliminates the codified definition of “weight of scientific evidence,” which EPA notes that it believes “inappropriately conflated the concepts of ‘weight of scientific evidence’ with ‘systematic review.’” According to EPA, “[t]he principles of systematic review are well-established and include ‘transparent and explicitly documented methods, consistent and critical evaluation of all relevant literature, application of a standardized approach for grading the strength of evidence, and clear and consistent summative language.’” (Citation omitted.) EPA states that it has codified the requirement to use and document systematic review methods to assess reasonably available information, and included flexibility to consider the appropriate level of review for a given evidence stream, while still ensuring EPA meets the requirements of TSCA Sections 26(h) and (i). In alignment with the recommendations from the National Academies of Science Engineering and Medicine (NASEM) report, Application of Systematic Review in TSCA Risk Evaluations, when EPA uses an alternative methodology, it will document why it has done so in lieu of the more traditional systematic review.

Weight of Scientific Evidence

The final rule eliminates the codified definition of “weight of scientific evidence” — “instead relying on long-established Agency guidance documents to guide weight of scientific evidence analyses under TSCA.” To meet the law’s requirement to base decisions in TSCA risk evaluations on the “weight of the scientific evidence,” EPA states that it expects to rely on established Agency guidance documents. According to EPA, “[t]hese peer reviewed guidances provide consistency and formality to a process that looks to integrate multiple and often heterogenic lines of evidence.”

Process for EPA Revisions to Scope or Risk Evaluation Documents

As part of the proposed rule, EPA added procedures and criteria for whether and how EPA would endeavor to revise or supplement final scope documents, and draft or final risk evaluations. Under the final rule, with respect to final scope documents, subsequent changes — if any — to the scope of the risk evaluation after publication of the final scope will be reflected and described in the draft risk evaluation instead of a revised final scope document. In its discretion, EPA will publish a notice in the Federal Register notifying the public that EPA has made information regarding changes to the risk evaluation scope available in the docket before releasing the draft risk evaluation.

With respect to draft risk evaluations, EPA states that it will reflect and describe any changes to the draft document in the final risk evaluation rather than reissue the risk evaluation in a second draft form. EPA noted in the proposed rule that, where changes from draft to final are significant in nature, nothing would prevent it from seeking additional advice or feedback from its independent scientific advisors or additional public comment on relevant topics, provided that such actions can be completed within the timeframes Congress contemplated for TSCA risk evaluations. According to EPA, this ensures that feedback is appropriately considered and reflected without unduly delaying progress towards completion of the risk evaluation.

With respect to revision of final risk evaluations, the final rule codifies a general practice and certain exceptions to that practice. As general practice, where circumstances warrant revisiting a chemical risk evaluation that has already been issued in final, EPA states that it may identify that chemical as a potential candidate for high-priority designation, and follow the procedures at 40 C.F.R. Part 702, Subpart A. EPA may make exceptions to that general practice where revisions to a final risk evaluation outside of re-prioritization of a chemical are in the interest of protecting human health or the environment.

Process and Requirements for MRREs

According to EPA, “the current process for MRREs is unrealistic and unsustainable.” EPA notes that the current process “allows MRRE requesters to provide EPA with a narrow set of information relevant to only certain conditions of use; requires EPA to quickly grant or deny the request, and then starts the clock for EPA to complete an entire risk evaluation on the chemical substance with the three-year statutory deadline.” EPA states that its “proposed changes would require that more fulsome information be included in incoming requests, allow EPA additional time to properly review requests and determine any additional information needs prior to initiating the evaluation, and provide flexibility in the process to accommodate additional data collection or development during the risk evaluation.” After considering the comments, EPA is codifying much of the regulatory text at 40 C.F.R. Section 702.45 as proposed. EPA “refer[s] the public to the preamble to the proposed rule for a more fulsome discussion of each of the substantive provisions, and EPA’s expected implementation.”

Scope of Request

The 2017 final rule allowed manufacturers to request a risk evaluation on particular COUs of interest to the requesting manufacturer, “leaving the Agency with the heavy burden of identifying the remaining conditions of use for the chemical substance.” According to EPA, for some, this provision created the misperception that, in instances where the requesting manufacturer only identified a narrow set of circumstances, EPA would or could carry out a similar, narrowly scoped risk evaluation. The final rule amends this language so that manufacturers are only permitted to make requests for evaluations of a chemical substance, not individual COUs or subsets of COUs, consistent with the statutory language in TSCA Section 6(b)(4)(C).

Contents of Request

The final rule includes specific updates to the required contents of an MRRE, and the criteria upon which EPA will judge completeness and sufficiency. MRRE requests must identify all intended, known, and reasonably foreseen circumstances of the chemical’s manufacture, processing, distribution in commerce, use, and disposal, and provide all available information regarding the chemical’s hazards and exposures. In the context of preparing an MRRE request and to meet the requirements in 40 C.F.R. Section 702.45(c), EPA states that it believes that “due diligence would, at a minimum, involve a thorough search and collection of publicly available information on the chemical’s hazards, exposures and conditions of use.” EPA expects that requesting manufacturers conduct a reasonable inquiry not only within the full scope of their organization regarding manufacturing processes and products (including imports), but also outside of their organization to fill gaps in knowledge. The final rule strikes the text regarding identification of PESS that the manufacturer believes to be relevant as “EPA must ultimately identify PESS — not the requesting manufacturer.”

EPA Process for Reviewing Requests

Under the final rule, upon receipt of an MRRE, EPA will provide the public with notice and begin reviewing the request for completeness. Where the MRRE request appears complete, EPA will open a docket for the MRRE and supporting information and solicit public comment. Following a second review, where EPA believes there is sufficient information, EPA will grant the request and publish a draft list of COUs and solicit additional comment. Following this comment period, and when EPA believes it has all necessary information, EPA states that it will formally initiate the evaluation and follow all the same processes and requirements for EPA-initiated risk evaluations.

Interagency Collaboration

EPA is also codifying 40 C.F.R. Section 702.47 as proposed. According to the final rule, EPA continues to collaborate with other relevant federal agencies and plans to coordinate further with them regarding interagency engagement and collaboration when carrying out the functions and responsibilities assigned to the Agency under TSCA Section 6(b), “starting even before the initiation of the prioritization process.” EPA states that it intends to develop and, subject to the interests of federal agencies involved, execute Memoranda of Understanding (MOU) that memorialize these interagency information exchanges, review and comment, and collaboration best practices.

With respect to critical/essential uses by other federal agencies, EPA states that it recognizes that identification and documentation of such uses requires substantial and early interagency engagement, as well as safeguards for national security or other sensitive information. For each chemical substance, EPA intends to engage at least four times with interested federal agencies and departments: first, before EPA begins the prioritization process for the substance; second, during the 9-12 month prioritization process; third, during the development of the draft risk evaluation; and fourth, after the draft risk evaluation has been released for public comment. At each engagement, in addition to receiving any information about the substance federal agencies wish to share, EPA would share scientific and other information about its progress on the risk evaluation, including any information it has developed related to federal agency uses of the substance.


The Acta Group (Acta®) stated on October 30, 2023, that “the proposed rule is potentially the most impactful that the Biden-Harris Administration has issued under TSCA.” We can now state with certainty that EPA’s final rule is the most impactful the Biden-Harris Administration has issued under TSCA. We have many concerns with EPA’s final rule. Several of these concerns include EPA’s removal of scientific “guardrails” for ensuring robust risk evaluations; EPA’s significant expansion of the scope of risk evaluations; and EPA’s single risk determination approach (formerly known as the “whole-chemical” approach). Below, we elaborate on each of these stated concerns.

We previously expressed our concern about EPA’s intent on removing the definitions for best available science and weight of scientific evidence. In the preamble to the final rule, EPA assured the public of its decision to do so by stating that it “can say with confidence that the Agency is fully committed to meeting the requirements in the law, and to being transparent in each risk evaluation…As such, EPA is finalizing the removal of these definitions from the codified regulatory text.” In our view, EPA should have revised the definitions of best available science and weight of scientific evidence, thereby providing greater transparency to EPA’s decision-making and limiting the susceptibility of EPA’s TSCA Section 6 activities to an administration-by-administration or substance-by-substance interpretation of the scientific standards under TSCA Section 26. Further, EPA’s prospective good intentions will not address the existing lapses in its completed and ongoing TSCA work products that failed to meet the current codified regulatory definitions. For discussion, see the commentary to our memorandum dated October 30, 2023.

EPA’s final rule appears to ignore a broad scientific consensus about de minimis thresholds in favor of EPA evaluating every possible exposure scenario. EPA stated that it “is finalizing the changes to the rule ensuring EPA will not exclude conditions of use from consideration within the scope of TSCA risk evaluations.” This decision includes “production of the chemical as a byproduct, presence of the chemical in trace or de minimis amounts such as an impurity or within an article…”

While it is vitally important for EPA to evaluate potential sources of exposure, it is a waste of EPA’s scarce resources to chase down de minimis quantities contrary to decades of scientific support that defensible exposure thresholds exist and exposures below a threshold will not present unreasonable risks. After performing over 25,000 new chemical substance risk assessments, EPA created exposure modeling thresholds below which EPA was confident it would not identify unreasonable risk. For discussion, see our memorandum dated August 22, 2022. Unfortunately, EPA’s final rule codifies requirements that it disregard its own scientists’ published research on the applicability of exposure thresholds and similar exposure thresholds used by other offices within EPA (e.g., Office of Pesticide Programs) and by external agencies (e.g., U.S. Food and Drug Administration (FDA) and European Food Safety Authority). EPA’s requirements to identify every quantity and source of a chemical substance undergoing a TSCA risk evaluation raise questions about how this approach will aid with balancing resource expenditures, ensuring manageability of the TSCA Section 6 program, while appropriately protecting human health and the environment.

We were disappointed to see that EPA codified its “whole-chemical” approach in the final rule. In the preamble, EPA referred to this as a “single risk determination” and stated that “this approach reflects a plain reading of the statutory text and structure.” We respectfully disagree. In our opinion, EPA has applied a strained reading of the statute that impermissibly introduces a hazard-based standard under TSCA, a risk-based statute, by including COUs that are not identified as presenting unreasonable risks within EPA’s “single risk determination.” This approach, along with EPA’s assumptions about the lack of worker protection, will ensure that essentially all substances that EPA evaluates will be an unreasonable risk (until EPA gets to low hazard substances) necessitating risk management rules.

To compensate for the single determination, EPA committed to providing clearer risk communication on its determinations and revised 40 C.F.R. Section 702.39(f)(3) as follows:

EPA will determine whether a chemical substance does or does not present an unreasonable risk after considering the risks posed under the conditions of use and, where EPA makes a determination of unreasonable risk, EPA will identify the conditions of use that significantly contribute to such a determination.

We fail to see how this will aid with clarifying EPA’s stated point in the preamble that “EPA believes these risk communication issues are addressable, and it is a priority area the Agency is committed to improve upon…Where one or more conditions of use for the chemical present an unreasonable risk, the chemical substance itself necessarily presents an unreasonable risk.” EPA’s commitment to improve was broken almost immediately. We point to EPA’s April 30, 2024, news release, which states:

Biden-Harris Administration Finalizes Ban on Most Uses of Methylene Chloride, Protecting Workers and Communities from Fatal Exposure

Along with a sub-head:

Rule requires stronger worker safety requirements for remaining industrial uses

But EPA does not state in its press release that EPA found that workplaces with robust protections were not an unreasonable risk. EPA only states that it is requiring workplace protection.  Unsurprisingly, subsequent media reporting does not mention that EPA found any COUs were not an unreasonable risk. EPA concluded that use of methylene chloride in compliance with EPA’s Workplace Chemical Protection Program (WCPP) does not pose an unreasonable risk. We do not question that misuse of methylene chloride may lead to deaths, but, given that consumer uses had already been banned, a more accurate headline is:

Biden-Harris Administration Finalizes Rules to Ensure That Workers Are Protected While Using Methylene Chloride

EPA further stated in the preamble that “a single risk determination on the chemical substance does not shift burdens from EPA to industry.” This may be true, but it will likely lead to potential liability concerns (e.g., toxic torts) over EPA’s single determination that “Chemical X presents unreasonable risks” even in cases where robust protections were present. The fact that those workplaces could defend against such lawsuits does not eliminate the costs and business risks from those lawsuits. This risk is exacerbated by EPA’s updated approach and methodology for evidence integration, which include causality statements (e.g., “Chemical X likely causes developmental toxicity in humans”). For discussion, see our memorandum dated December 21, 2023.

Finally, we expect that EPA’s final rule will eliminate the value of MRREs. We agree with EPA’s amendments to the final rule that MRREs will be performed on a chemical substance and not individual COUs or subsets of COUs, but EPA’s single determination approach will only ensure an MRRE will lead to EPA concluding the substance is an unreasonable risk and generate negative press.

Acta encourages interested parties to  review EPA’s final rule. The prospective impacts of EPA’s new codified approaches in the final rule may impact chemistries that for some users are not currently regulated under TSCA because EPA’s single determination will undoubtedly be interpreted to include all uses, even those not subject to TSCA. We encourage entities to monitor EPA’s prioritization activities under TSCA and diligently provide information and comments, as appropriate.