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March 8, 2022

EPA Publishes Final Scope of D4 Risk Evaluation, Seeks Comment on Draft Revision to PV29 Risk Determination

Bergeson & Campbell, P.C.

On March 7, 2022, the U.S. Environmental Protection Agency (EPA) announced the availability of the final scope of the risk evaluation to be conducted for octamethylcyclotetra-siloxane (D4), a chemical substance for which EPA received a manufacturer request for risk evaluation under the Toxic Substances Control Act (TSCA). 87 Fed. Reg. 12696. The scope document includes the conditions of use (COU), hazards, exposures, and the potentially exposed or susceptible subpopulations (PESS) that EPA plans to consider in conducting the risk evaluation for this chemical substance. EPA also published a separate notice announcing the availability of and requesting public comment on a draft revision to the risk determination for the Colour Index Pigment Violet 29 (PV29) risk evaluation. 87 Fed. Reg. 12690. EPA states that the draft revision finds that PV29, as a whole chemical substance, presents an unreasonable risk of injury to health when evaluated under its COUs. The draft revision would supersede the COU-specific no unreasonable risk determinations in the January 2021 PV29 risk evaluation, would withdraw the associated order, and would make a revised determination of unreasonable risk for PV29 as a whole chemical substance. EPA notes that in addition, the draft revised risk determination does not reflect an assumption that workers always appropriately wear personal protective equipment (PPE). Comments on the draft revision to the PV29 risk determination are due April 21, 2022.

Final Scope of D4 Risk Evaluation

According to the final scope, EPA plans to evaluate manufacturing (including importing); processing; distribution in commerce; industrial, commercial, and consumer uses; and disposal of D4 in its risk evaluation. D4 is manufactured (including imported) in the United States. The final scope states that D4 is processed as a reactant; incorporated into a formulation, mixture, or reaction product; and incorporated into articles. The identified processing activities also include the repackaging and recycling of D4. D4 is primarily used to make other silicone chemicals and as an ingredient in consumer products regulated by the Federal Food, Drug, and Cosmetic Act (FFDCA). Commercial and consumer uses were identified, including adhesives and sealants, automotive care products, laundry and dishwashing products, paints and coatings, and other plastic and rubber products.

Some of the COUs were identified in the manufacturer request as circumstances on which EPA was requested to conduct a risk evaluation. EPA identified other COUs from information reported to EPA through its Chemical Data Reporting (CDR) rule, published literature, and consultation with stakeholders for uses currently in production and uses whose production may have ceased. EPA states that in the final scope, it added the following COUs due to additional information from stakeholder outreach, public comments, and further research: processing aid (e.g., component in an antifoaming agent); commercial use in laundry and dishwashing products; and industrial use in general aircraft maintenance.

According to the final scope, EPA considered “reasonably available information” and comments received on the draft scope in determining the human and environmental exposure pathways, routes, receptors, and PESS for inclusion in the final scope. EPA plans to evaluate the following human and environmental exposure pathways, routes, receptors, and PESS in the scope of the risk evaluation:

  • Occupational Exposure: EPA plans to evaluate exposures to workers and occupational non-users (ONU) via the inhalation route, including incidental ingestion of inhaled dust, and exposures to workers via the dermal route associated with the manufacturing, processing, use, and disposal of D4. EPA plans to analyze dermal exposure for workers and ONUs to mists and dust that deposit on surfaces;
  • Consumer and Bystander Exposure: EPA plans to evaluate inhalation, dermal, and oral exposure to D4 for consumers and bystanders from the use of adhesives and sealants; automotive care products; cleaning and furnishing care, fabric, textiles, and leather materials not covered elsewhere; laundry and dishwashing products; paints and coatings; plastics and rubber products not covered elsewhere; toys, playground, and sporting equipment; and the direct contact and/or mouthing of products or articles containing D4 for consumers;
  • General Population Exposure: EPA plans to evaluate general population exposure to D4 via the oral route from drinking water, surface water, groundwater, soil, human milk, and fish ingestion; via the inhalation route from ambient air; and via the dermal route from contact with drinking water, surface water, groundwater, and soil;
  • PESS: EPA plans to include children; women of reproductive age (e.g., women who may be pregnant or breastfeeding); populations with elevated fish ingestion such as subsistence fishers and indigenous and native populations; workers; ONUs; consumers; and bystanders as PESS in the risk evaluation; and
  • Environmental Exposure: EPA plans to evaluate exposure to D4 for aquatic and terrestrial receptors.

Draft Revision to PV29 Risk Determination


As reported in our July 1, 2021, memorandum, on June 30, 2021, EPA announced plans to revise specific aspects of the first ten risk evaluations issued under TSCA to ensure that the risk evaluations appropriately identify unreasonable risks and thereby help ensure the protection of human health and the environment. The policy changes include:

  • Whole Chemical Approach: Under the previous Administration, EPA made separate unreasonable risk determinations for every COU of a chemical. For the first ten chemicals evaluated under TSCA and for any similar chemical that presents significant risks across many uses, EPA will assess and analyze each COU but then make a determination of unreasonable risk just once for the whole chemical when it is clear that the majority of the COUs warrant one determination; and
  • Use of PPE: In the final risk evaluations for the first ten chemicals, the previous Administration generally assumed that workers were always provided, and used, PPE appropriately. EPA states that data on violations of PPE use suggest that assumptions that PPE is always provided to workers, and worn properly, are not justified, however. EPA is therefore revisiting the assumption that PPE is always used in occupational settings when making risk determinations for a chemical. Instead, EPA plans to consider information on use of PPE, or other ways industry protects its workers, as a potential way to address unreasonable risk during the risk management process.

As reported in our January 25, 2021, memorandum, EPA reviewed 14 COUs for PV29, including as an intermediate for other perylene pigments, as well as a component of paints, coatings, industrial carpeting, and plastic and rubber products used primarily in the automobile industry, in ink used for commercial printing, and in consumer watercolors and artistic paints. EPA determined that there are unreasonable risks to workers and ONUs from ten out of 14 COUs. EPA found no unreasonable risks to the environment, consumers, or the general public.

Whole Chemical View of the Unreasonable Risk Determination for PV29

EPA proposes that a whole chemical approach better aligns with TSCA’s objective of protecting health and the environment. For PV29, EPA states that it favors the whole chemical approach “based in part on the benchmark exceedances for multiple conditions of use (spanning across most aspects of the chemical lifecycle — from manufacturing (including import), processing, commercial and industrial use, and disposal) for health of workers and occupational non-users and the irreversible health effects (specifically alveolar hyperplasia) associated with PV 29 exposures.” According to EPA, since the chemical-specific properties cut across the COUs within the scope of the risk evaluation, EPA’s risk findings and conclusions encompass the majority of those COUs, and EPA is better positioned to achieve its TSCA objectives for PV29 when issuing a whole chemical determination. EPA concludes that its risk determination for PV29 “is better characterized as a whole chemical risk determination rather than condition-of-use-specific risk determinations.”

EPA would base the revisions to the unreasonable risk determination on the existing risk characterization section of the risk evaluation (section 4 of the risk evaluation), and the revisions would not involve additional technical or scientific analysis. EPA states that it intends to change the risk determination to a whole chemical approach without considering the use of PPE and does not intend to amend, nor does a whole chemical approach require amending, the underlying scientific analysis of the risk evaluation in the risk characterization section of the risk evaluation. EPA notes that it views the peer-reviewed hazard and exposure assessments and associated risk characterization “as robust and upholding the standards of best available science and weight of the scientific evidence” per TSCA Sections 26(h) and (i).

EPA seeks public comment on the draft superseding unreasonable risk determination for PV29, including a list of COU-specific risks driving the unreasonable risk determination for the chemical substance as a whole. For purposes of TSCA Section 6(i), EPA states that it is making a risk determination on PV29 as a whole chemical. Under the revised approach, EPA proposes to supersede the no unreasonable risk determinations (and withdraw the associated order) for PV29 that were premised on a condition-of-use-specific approach to determining unreasonable risk.

Use of PPE for the Risk Evaluation

According to the notice, when characterizing the risk to human health from occupational exposures during risk evaluation under TSCA, “EPA believes it is appropriate to evaluate the levels of risk present in baseline scenarios where no mitigation measures are assumed to be in place.” EPA acknowledges that in some cases, baseline conditions may reflect certain mitigation measures, such as engineering controls, in instances where exposure estimates are based on monitoring data at facilities that have engineering controls in place. EPA states that this approach considers the risk to PESS of workers who may not be covered by Occupational Safety and Health Administration (OSHA) standards, such as self-employed individuals and public sector workers who are not covered by a State Plan. In addition, EPA states that it believes it is appropriate to evaluate the levels of risk present in scenarios considering applicable OSHA requirements (e.g., chemical-specific permissible exposure limits (PEL) and/or chemical-specific PELs with additional substance-specific standards), as well as scenarios considering industry or sector best practices for industrial hygiene “that are clearly articulated to the Agency.” Consistent with this approach, the January 2021 PV29 risk evaluation characterized risk to workers both with and without the use of PPE.

EPA states that when undertaking unreasonable risk determinations as part of TSCA risk evaluations, however, it “does not believe it is appropriate to assume as a general matter that an applicable OSHA requirement or industry practice is sufficient to address the risk, applicable to all potentially exposed workers, or consistently and always properly applied.” Therefore, going forward, EPA intends to make its determination of unreasonable risk from a baseline scenario that does not assume compliance with OSHA standards, including any applicable exposure limits or requirements for use of respiratory protection or other PPE. Making unreasonable risk determinations based on the baseline scenario “reflects EPA’s recognition that unreasonable risk may exist for subpopulations of workers that may be highly exposed because they are not covered by OSHA standards, such as self-employed individuals and public sector workers who are not covered by a State Plan, or because their employer is out of compliance with OSHA standards, or because EPA finds unreasonable risk for purposes of TSCA notwithstanding OSHA requirements.”

In accordance with this approach, EPA proposes that the draft revision to the PV29 risk determination not rely on assumptions regarding the occupational use of PPE in making the unreasonable risk determination under TSCA Section 6; rather, EPA would consider the use of PPE during risk management. EPA states that as a general matter, when undertaking risk management actions, it “intends to strive for consistency with applicable OSHA requirements and industry best practices, including appropriate application of the hierarchy of controls, when those measures would address an unreasonable risk; ensure the EPA requirements apply to all potentially exposed workers; and develop occupational risk mitigation measures to address any unreasonable risks identified by EPA.” Consistent with TSCA Section 9(d), EPA will consult and coordinate TSCA activities with OSHA and other relevant federal agencies to achieve the “maximum applicability” of TSCA while avoiding duplicative requirements. Informed by the mitigation scenarios and information gathered during the risk evaluation and risk management process, EPA “might propose rules that require risk management practices that may be already common practice in many or most facilities.”

EPA states that removing the assumptions of PPE use in making the whole chemical risk determination for PV29 would not alter the COUs driving EPA’s unreasonable risk determination for PV29 as a whole chemical. According to EPA, the draft revision to the risk determination would clarify that EPA does not rely on the assumed use of PPE when making the risk determination for the whole substance. EPA requests comment on this potential change.


B&C commends EPA for advancing its throughput of work products under TSCA Section 6 despite continuing staffing and resource limitations. B&C notes, however, that there are a number of unresolved issues in the final D4 scope document, the final PV29 risk evaluation, and the draft revised PV29 risk determination that warrant discussion and suggested action by readers.

Final D4 Scope Document

The data collection and screening of information in the final D4 scope document was based on a draft systematic review (SR) protocol that EPA released for public comment on December 20, 2021. Since its release, EPA has scheduled a public virtual meeting April 19-21, 2022, for the Science Advisory Committee on Chemicals (SACC) to peer review the draft SR protocol. It is unclear, however, how EPA will proceed on the final D4 scope document if the SACC determines that EPA’s draft SR protocol does not meet the scientific standards under TSCA Section 26.

Final PV29 Risk Evaluation

EPA stated that it “does not intend to amend, nor does a whole chemical approach require amending, the underlying scientific analysis of the [PV29] risk evaluation in the risk characterization section of the risk evaluation.” B&C understands EPA’s view, given that the changes relate to policy changes that EPA announced. We note, however, that the policy changes will not address two fundamental scientific issues in the final PV29 risk evaluation, nor will they address a potential environmental justice issue, as discussed below.

Scientific issue number 1: EPA stated in the final PV29 risk evaluation that it used an SR process to meet the scientific standards for best available science and weight of scientific evidence, under TSCA Section 26(h) and 26(i), respectively. The U.S. National Academies of Sciences, Engineering, and Medicine concluded, however, that EPA’s approach “to systematic review does not adequately meet the state-of-practice.” As with D4, EPA does not appear to have a plan to address this weakness.

Scientific issue number 2: EPA used the deposited dose of an analog (i.e., carbon black) in the lungs of rats, mice, and hamsters as the dose metric for PV29 in the final PV29 risk evaluation. EPA has acknowledged, however, that the best available science for poorly soluble particles, like carbon black and PV29, supports using the retained mass in the lungs as the proper dose metric. EPA does not explain why it is not using the best available science in this case.

Environmental justice issue: EPA dismissed the human equivalent concentration (HEC) derived using the deposited dose from hamsters (i.e., 0.16 mg/m3) and used an HEC derived using deposited dose from rats (i.e., 0.28 mg/m3) for quantifying risks. In other words, EPA chose a less conservative HEC from which to quantify risks, without adequately articulating the scientific basis for doing so.

Draft Revised PV29 Risk Determination

EPA’s whole chemical approach appears to be impermissible under the final risk evaluation rule, codified at 40 C.F.R. Part 702, Subpart B. For example, 40 C.F.R. Section 702.47 unambiguously states:

As part of the risk evaluation, EPA will determine whether the chemical substance presents an unreasonable risk of injury to health or the environment under each condition of uses [sic] within the scope of the risk evaluation …

We recognize that EPA has the discretion to reinterpret TSCA. EPA must, however, follow the required procedures to do so (i.e., notice and comment before rulemaking to revise the Final Risk Evaluation rule). In addition, EPA does not explain how its policy decision to assume that workers do not always wear PPE, as required by OSHA, and EPA then assumes that workers never wear PPE, meets the definition of reasonably foreseen. This interpretation is especially problematic when considering the legislative record for the TSCA amendments. For example, the U.S. Congressional record specifically states, “The term [conditions of use] is not intended to include “intentional misuse” of chemicals.” To address this apparent departure from Congressional intent, EPA points to self-employed and other employees who are not covered by OSHA, but does not explain how these employees might be exposed to PV29 during the COUs that EPA identifies as an unreasonable risk. Furthermore, if the unreasonable risk is as widespread as EPA concludes in its assessment of PV29, and, as is the case, that risk is present because of a simple physicochemical property (as a respirable insoluble particle), one would think that EPA would want to work with OSHA and other regulatory agencies to implement protective measures against the hundreds, if not thousands, of respirable insoluble particles. For example, EPA could work with OSHA to lower the PEL for particles not otherwise regulated (PNOR). TSCA’s substance-by-substance mechanism is a remarkably inefficient way to address this concern.

We have summarized a few issues of which readers should be aware with EPA’s new policy directions. Readers should, however, be mindful of two important points. First, the above list of issues is not comprehensive; rather, it was prepared to provide readers with representative examples of the types of issues presented in EPA’s documents. Second, readers should be aware that even if they do not engage in activities related to D4 or PV29, EPA’s policy decisions in these documents will be cross-cutting and will likely end up affecting every chemical EPA assesses under TSCA Section 26. Therefore, B&C encourages readers to consider the broad implications of EPA’s new policy directions and to submit public comments where appropriate.