EPA Releases Draft Risk Evaluation Documents for Two Phthalates for Public Comment and Peer Review
Released May 17, 2024
Today, the U.S. Environmental Protection Agency (EPA) released its draft risk evaluation for Diisodecyl phthalate (DIDP) and the physical chemical, fate, and hazard assessments for Diisononyl phthalate (DINP) prepared under the Toxic Substances Control Act (TSCA). EPA preliminarily determined that all but one of the uses of DIDP EPA evaluated under TSCA do not contribute to unreasonable risk to human health. Additionally, EPA preliminarily determined that DINP causes liver damage at lower concentrations than DIDP, and unlike DIDP, could cause cancer at higher levels of exposure.
The primary uses of DIDP and DINP under TSCA are use as plasticizers in polyvinyl chloride (PVC) in consumer, commercial, and industrial applications. There are other uses of DIDP and DINP that are generally excluded from TSCA, such as personal care products, cosmetics, and food contact materials, and EPA did not evaluate risk associated with these uses.
The risk evaluations of DIDP and DINP are the first two manufacturer-requested risk evaluations EPA has conducted. Under TSCA, manufacturers can request that EPA conduct risk evaluations on chemicals they manufacture. EPA received and granted manufacturer requests for risk evaluations of DIDP and DINP in 2019.
DIDP
DIDP is used to make building and construction materials; automotive care and fuel products; and other commercial and consumer products including adhesives and sealants, paints and coatings, electrical and electronic products. When it is manufactured or used to make products, DIDP can be released into the water where most of it will end up in the sediment at the bottom of lakes and rivers. If it is released into the air, it will attach to dust particles and then be deposited onto land or into water. Indoors, DIDP has the potential over time to come out of products and adhere to dust particles. If it does, people could inhale or ingest dust that contains DIDP. EPA found that DIDP has the potential to cause developmental toxicity and harm the liver. However, like U.S. Consumer Product Safety Commission (CPSC), Health Canada, the European Chemicals Agency, and Australia’s National Industrial Chemicals Notification and Assessment Scheme, EPA did not find enough evidence to preliminarily determine that DIDP causes cancer.
In the draft risk evaluation for DIDP, EPA preliminarily determined that DIDP poses unreasonable risk of injury to human health to workers exposed to the chemical. EPA also preliminarily determined that DIDP does not pose unreasonable risk of injury to human health for consumers or the general population or pose unreasonable risk to the environment. EPA preliminarily determined that only one of the 47 conditions of use of DIDP that are subject to TSCA contribute to the unreasonable risk to workers: if unprotected workers were to spray adhesives and sealants that contain DIDP with high-pressure sprayers, because doing so could create high concentrations of DIDP in mist that an unprotected worker could inhale. EPA is not certain whether this particular use of DIDP is ongoing, and expects that public comments on this draft will help address this uncertainty.
EPA did not evaluate uses and potential exposure pathways which are not by statute covered by TSCA, such as food packaging. Past assessments, including the CPSC’s risk assessment found that DIDP exposure comes primarily from diet for women, infants, toddlers, and children. It is possible that DIDP could pose risks to human health through uses or exposure pathways that are not regulated under TSCA. While EPA is preliminarily concluding in this draft risk evaluation that only one TSCA condition of use contributes to its draft unreasonable risk finding for DIDP, this conclusion cannot be extrapolated to form conclusions about uses of DIDP that are not subject to TSCA, and that EPA did not evaluate.
DINP
Although DIDP and DINP have similar uses, EPA identified several important differences in the potential effects on human health posed by DIDP and DINP. Both DIDP and DINP can cause developmental toxicity and liver damage, but DINP is considered the more toxic of the two because effects are observed at lower levels of exposure in rodent models. For DIDP, EPA determined that the evidence is not strong enough to conclude that it can cause cancer in people. By contrast, EPA determined that DINP could cause cancer at higher levels of exposure than those that cause liver damage and developmental toxicity.
Because of these hazard differences, EPA is also requesting peer review on the DINP human hazard assessments before releasing the full draft risk evaluation for public comment later this year. While EPA will not be requesting peer review on the full risk evaluation for DINP, the peer review on the DINP hazard assessments will cover all the scientific questions that need to be addressed for the DINP risk evaluation. For DINP, EPA will use the same exposure models used for the DIDP risk evaluation that are being released for peer review today and may use the same models for the other phthalate chemicals as well.
Finally, as EPA previously described in the Draft Proposed Approach for Cumulative Risk Assessment of High-Priority Phthalates and a Manufacturer Requested Phthalate Under the Toxic Substance Control Act, which went to SACC peer review in 2023, the evidence suggests that DIDP does not cause effects on the developing male reproductive system commonly known as phthalate syndrome. However, DINP does have the potential to cause phthalate syndrome. Therefore, EPA is including DINP in its cumulative risk assessment along with five other phthalate chemicals that have the potential to cause phthalate syndrome, while DIDP is excluded from the cumulative risk assessment.
Next Steps
Upon publication of the Federal Register notice, EPA will accept public comments on the draft documents for 60 days via docket EPA-HQ-OPPT-2024-0073 at www.regulations.gov. The draft documents will also be peer reviewed by the Agency’s Science Advisory Committee on Chemicals (SACC). Following a call for nominations in February 2024, the biographical sketches of the candidates under consideration as prospective peer reviewers were posted for public comment in April 2024.
EPA will hold a virtual public meeting for the SACC to discuss the draft documents from July 30-August 2, 2024. Registration instructions for the meeting will be announced on the SACC website in early July 2024, including information about how to register to present oral comments during the meeting. For additional information, please see the Federal Register notice or contact the Designated Federal Official, Dr. Alaa Kamel kamel.alaa@epa.gov.
In addition, EPA will hold a preparatory virtual public meeting on July 23, 2024, for the SACC and the public to consider and ask questions regarding the scope and clarity of the draft charge questions and areas of review.
Any feedback received from the public and the SACC will be considered in order to inform the final risk evaluations for DIDP and DINP.
Read the draft risk evaluation for DIDP.
Read the draft physical chemical, fate, and hazard assessments for DINP.