On January 14, 2025, the U.S. Environmental Protection Agency (EPA) released the final risk evaluation for diisononyl phthalate (DINP) conducted under the Toxic Substances Control Act (TSCA). EPA states that it has determined that DINP presents an unreasonable risk of injury to human health because workers could be exposed to high concentrations of DINP in mist when spraying adhesive, sealant, paint, and coating products that contain DINP. According to EPA, DINP can cause developmental toxicity and harm the liver and can cause cancer at higher rates of exposure. EPA notes that DINP can also harm the developing male reproductive system, known as “phthalate syndrome,” and that it is including DINP in its cumulative risk analysis for six phthalates that demonstrate effects consistent with phthalate syndrome. EPA released this draft risk analysis on January 6, 2025.

According to EPA, DINP is used as a plasticizer to make flexible polyvinyl chloride (PVC) and to make building and construction materials; automotive articles; and other commercial and consumer products, including adhesives and sealants, paints and coatings, and electrical and electronic products. EPA notes that it conducted the risk evaluation for DINP at the manufacturer’s request.

EPA states that workers may be exposed to DINP when making products or otherwise using DINP in the workplace. According to EPA, when DINP is manufactured or used to make products, it can be released into the water where most will end up in the sediment at the bottom of lakes and rivers. If released into the air, DINP will attach to dust particles and be deposited on land or into water. Indoors, DINP has the potential over time to come out of products and adhere to dust particles that could be inhaled or ingested.

In the risk evaluation, EPA determined that DINP poses unreasonable risk of injury to human health when workers are exposed to the chemical under four conditions of use (COU) that represent approximately three percent of the DINP production volume in the United States. EPA states that it found that workers are at risk if they are unprotected from the DINP contained in spray-applied adhesives and sealants and paints and coatings. Spraying these products could create high concentrations of DINP in mist that an unprotected worker could inhale. EPA did not identify risk of injury to human health for consumers or the general population or the environment that would contribute to the unreasonable risk of DINP.

EPA notes that it did not evaluate uses and potential exposure pathways that are excluded by statute from TSCA, such as food additives or cosmetics. Past assessments, including the U.S. Consumer Product Safety Commission’s (CPSC) risk assessment, found that DINP exposure comes primarily from diet for women, infants, toddlers, and children. According to EPA, while it is possible that DINP could pose risks to human health through uses or exposure pathways that are not regulated under TSCA, EPA’s risk evaluation and unreasonable risk determination cannot be extrapolated to form conclusions about uses of DINP that are not subject to TSCA and that EPA did not evaluate.

Next Steps

EPA states that it will now begin the risk management process to address the unreasonable risk presented by DINP. EPA will release a proposed rule under TSCA Section 6 to protect workers from the identified risks.

Commentary

Bergeson & Campbell, P.C. (B&C^®) is pleased that EPA has made progress on the risk evaluation for DINP. EPA’s evaluation efforts, however, fall short. In the summary statement of the Federal Register notice, EPA states “EPA used the best available science to prepare this final risk evaluation and determined, based on the weight of scientific evidence, that DINP poses unreasonable risk to human health.” EPA makes this conclusion presumably because of its “single determination” (formerly referred to as the whole chemical approach) construction. What concerns us is that this statement condemns DINP; it is a characterization of blunt force, and a reasonable reader would conclude that any COU poses an unreasonable risk to industrial and commercial workers, consumers, and the general population. EPA did a better job on its website for the final risk evaluation for DINP, where EPA states “EPA has determined that DINP presents an unreasonable risk of injury to human health, because workers could be exposed to high concentrations of DINP in mist when spraying adhesive, sealant, paint, and coating products that contain DINP.” EPA, however, does not explain that its conclusion is based on its assumption that workers are not protected. Taken literally, EPA’s statement is that all such workers are at risk, not just unprotected workers. This may seem trivial, but words matter, especially those written by EPA. EPA may wish going forward to be a bit more deliberate in framing its bottom line conclusion and clearly communicate to the public, especially workers, what the risks are and the importance of following the hierarchy of controls, including using respiratory protection, all without unduly alarming workers or the public.

It is critically important that the final risk evaluation accurately represent the COUs that are an unreasonable risk because that final determination provides the basis for any risk management rule. The very limited scope of the COUs that are an unreasonable risk suggests that any risk management rule would also be narrowly tailored. It remains to be seen if EPA will seek to issue bans for DINP for any COU or if EPA will impose a Workplace Chemical Protection Program (WCPP) that addresses the specific COUs for which EPA identifies unreasonable risk.