U.S. Environmental Protection Agency (EPA) is advancing its review of four chemicals under the Toxic Substances Control Act (TSCA)—1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8-hexamethylcyclopenta [g]-2-benzopyran (HHCB), phthalic anhydride, o-dichlorobenzene (oDCB) and p-dichlorobenzene (pDCB)—by releasing draft documents related to the review of these chemicals and convening a peer review meeting of the Science Advisory Committee on Chemicals (SACC). These chemicals are found in fragrances, paints, coatings, cleaners, and industrial processes, meaning decisions in these cases can directly affect the air we breathe at work and at home.
Released today are the draft risk evaluations for HHCB and phthalic anhydride and the draft hazard assessments and supporting documents for oDCB and pDCB. These draft documents are now available for public comment and independent scientific peer review—two essential steps in ensuring the integrity, radical transparency, and quality of EPA’s chemical safety assessments.
The release of these draft documents marks a critical milestone in EPA’s ongoing work to assess potential risks to human health and the environment from chemical exposures. The agency is committed to using the best available science and adhering to rigorous, gold standard scientific practices throughout the evaluation process. This includes the application of standardized metrics and evaluation methods such as systematic review, robust analyses of available data, and, when appropriate, the use of data from new approach methods (NAMs). For example, EPA used transcriptomic analysis, a molecular approach that measures differences in gene expression that informs cancer and non-cancer effects for both pDCB and oDCB. The draft risk evaluation for phthalic anhydride exemplifies EPA’s use of NAMs by applying computational approaches that integrate data from in chemico studies and in vitrostudies in human tissues to inform dermal hazard characterization within established frameworks (i.e., adverse outcome pathways) that organize toxicity data in a way that can be used to link cellular changes caused by chemical exposure to health impacts. Application of these data were informed by EPA’s collaborations with other government organizations, animal welfare organizations, and in vitro method developers who enabled the inclusion of cutting-edge science.
The documents released today show:
- HHCB: For HHCB, a fragrance ingredient used in air care and cleaning products, EPA’s draft risk evaluation did not identify an “unreasonable risk” under current law across 22 conditions of use. EPA used real‑world monitoring data and conservative modeling to look at exposures to workers, consumers, and the general population, including Tribal communities and subsistence fishers. We are inviting comments on whether there is a need for additional scientific considerations.
- Phthalic anhydride: For phthalic anhydride, used to make paints, coatings, adhesives, and plastics, EPA’s draft risk evaluation identifies unreasonable risk to workers from dermal and inhalation exposure (36 conditions of use); unreasonable risk to consumers from dermal and inhalation exposure (2 conditions of use) in certain uses of solvent‑based products. Because this chemical is a strong respiratory and skin sensitizer, EPA will move quickly, after peer review and public comment, to finalize the risk evaluation. Should EPA continue to find unreasonable risk, EPA will then propose risk management actions to reduce or eliminate these unsafe exposures in workplaces and in the home.
- pDCB and oDCB: For pDCB and oDCB, chemicals used in manufacturing and cleaning, EPA’s draft hazard assessments confirm serious non‑cancer health concerns, including effects on the liver, kidneys, respiratory system, and the nervous and reproductive systems. EPA used modern molecular tools (transcriptomics) to develop health‑protective benchmarks for inhalation, oral, and dermal exposure. While current evidence suggests pDCB is not likely to cause cancer in people and that a formal quantitative cancer assessment for oDCB is not warranted, EPA recognizes that many families and advocates remain concerned about long‑term cancer risks. Peer review and public comment will allow independent experts and the public to closely review our cancer analyses and identify scientific information that will inform our development of draft and final risk evaluations for these chemicals.
EPA emphasizes that these documents are draft and do not represent final agency determinations regarding the risks posed by these chemicals. The findings and conclusions may change based on feedback received during the public comment period and peer review process. Additionally, the release of these draft evaluations does not alter or impact any existing protections, regulations, or risk management measures currently in place for these chemicals. All current safeguards remain fully effective.
Following the close of the public comment period and completion of peer review, EPA will carefully consider all input before finalizing the risk evaluations in accordance with TSCA requirements.
June 2026 Peer Review Meeting
On June 8-12, 2026, EPA will hold a virtual public meeting of the SACC to review the draft risk evaluations for HHCB and phthalic anhydride and technical support documents for pDCB and oDCB.
EPA will also hold a preparatory virtual public meeting on May 26, 2026, for the SACC and the public to consider and ask questions regarding the scope and clarity of the draft charge questions that will be used in the peer review meeting.
EPA will publish registration links for the June SACC meeting and the May preparatory meeting on the SACC website approximately one month prior to each meeting.
The draft risk evaluations, draft hazard assessments, related supporting materials, and draft charge questions will be available in the peer review docket EPA-HQ-OPPT-2026-1189 at www.regulations.gov. To have your comments on the draft risk evaluations, draft hazard assessments, related supporting materials, and draft charge questions considered by the SACC for peer review, they must be submitted to the peer review docket listed above no later than 45 days after publication of the Federal Register Notice announcing the peer review.
Draft Risk Evaluation for HHCB
HHCB is a liquid used as an odor agent in fragrances, such as air care and cleaning products. EPA’s draft risk evaluation found that HHCB does not present an unreasonable risk of injury to human health or the environment under the conditions of use, including manufacture, processing, commercial and consumer use, and disposal. This preliminary determination of no unreasonable risk applies to workers, consumers, and the general population (including subsistence fishers and Tribal populations), as well as aquatic and terrestrial ecological receptors.
In the draft risk evaluation, EPA used both real world monitoring data and modelling to assess potential risks for workers from inhalation exposure via dust or vapor, inhalation exposure to consumers via continuous action air fresheners, and to the general population from fish and water consumption. The combination of screening-level approaches and refined analysis resulted in the very conservative evaluation and a preliminary finding of no unreasonable risks. This conclusion is also supported by the European Union and the Australian National Industrial Chemicals Notification and Assessment Scheme.
In addition to the public comment period associated with the peer review docket, the draft risk evaluation will also be available for public comment in a TSCA docket. Upon publication of the Federal Register notice announcing the availability of the draft risk evaluation, EPA will accept public comments on the draft risk evaluation for 60 days in the HHCB TSCA docket EPA-HQ-OPPT-2018-0430 on www.regulations.gov.
Draft Risk Evaluation for Phthalic Anhydride
Phthalic anhydride is a white solid used as a reactant for producing adhesives, laboratory chemicals, and various paints, coatings, and plastic materials. Once in the environment, phthalic anhydride can react with water or moisture in the air to become phthalic acid, and therefore EPA also evaluated risks from exposure phthalic acid for its assessment of risks to the general population and risks to the environment. Phthalic anhydride is a strong respiratory sensitizer and dermal sensitizer. In contrast, phthalic acid is not.
EPA’s draft risk evaluation found that phthalic anhydride presents an unreasonable risk for workers and from dermal and inhalation exposure across manufacturing, processing, industrial, and commercial conditions of use. The draft risk evaluation also found unreasonable risk to consumers from dermal and inhalation exposure in certain uses of solvent based paints, coatings, adhesives, and sealants. The draft risk evaluation did not identify unreasonable risk to the general population or the environment.
In addition to the public comment period associated with the peer review docket, the draft risk evaluation will also be available for public comment in a TSCA docket. Upon publication of the Federal Register notice announcing the availability of the draft risk evaluation, EPA will accept public comments on the draft risk evaluation for 60 days in the phthalic anhydride TSCA docket EPA-HQ-OPPT-2018-0459on www.regulations.gov.
Technical Support Documents for pDCB and oDCB
EPA is releasing draft human health and environmental hazard assessments for pDCBand oDCB. These assessments present a robust review of available studies related to potential harm to human health and the environment. They compile and evaluate reasonably available evidence, calculate the levels at which these chemicals may cause harm to human health and the environment, and will inform the forthcoming draft risk evaluations that integrate hazard and exposure to characterize risk.
Along with these draft hazard assessments EPA is also releasing an assessment of the use of NAMs related to both chemicals. In support of Administrator Zeldin’s commitment to end animal testing at EPA, the agency used new scientific techniques and approaches to screen for health effects, including transcriptomics, to develop conservative risk estimates.
pDCB is a colorless to white crystalline solid with a strong, pungent odor used to manufacture plastics and other chemicals and as an odor agent. Non-cancer hazards associated with pDCB exposure include respiratory system, liver, and kidney toxicity as well as neurotoxicity and developmental and reproductive toxicity. For pDCB, the agency’s draft assessment shows this chemical is not likely to cause cancer in humans. This conclusion is based on long-term studies showing that while pDCB causes mice to develop liver tumors, due to the differences in how our bodies work, exposures of humans to pDCB will not result in liver tumors.
oDCB is a colorless liquid with a pleasant, aromatic odor used in the manufacture of dyes, paints, and pigments, and in products used for cleaning, degreasing, and painting. For oDCB, EPA used transcriptomics to screen for gene expression. Using this approach, EPA was able to develop conservative and protective inhalation, oral and dermal risk estimates and fill in gaps found in existing studies on this chemical. Non-cancer hazards associated with oDCB exposure include respiratory system, liver, and kidney toxicity. Using the ReCAAP framework, a weight of evidence framework, EPA determined a quantitative cancer assessment is not warranted for this chemical.
EPA will release draft risk evaluations for pDCB and oDCB prior to the June SACC meeting. However, because of the unique and novel scientific approaches used in the human health and environmental assessments for these chemicals, the agency is seeking peer review from the SACC on the draft technical documents released today. EPA anticipates that the reminder of the draft risk evaluations for these chemicals will use scientific approaches and techniques the SACC has previously commented on; therefore, EPA does not expect the need for an additional peer review of the forthcoming risk evaluations for pDCB and oDCB. The agency will use the feedback from the SACC to inform the final risk evaluations.
Upon publication of the peer review Federal Register notice, EPA will accept public comments on these documents for oDCB and pDCB for 45 days in the peer review docket EPA-HQ-OPPT-2026-1189 on www.regulations.gov. These documents, along with the draft risk evaluations for these chemicals, will also be available for public comment in separate TSCA dockets later this year.
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