U.S. EPA Finalizes Risk Evaluation for DINP and DIDP: No Broad Risks Found

In January 2025, the U.S. Environmental Protection Agency (EPA) published final risk evaluation for diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP), two widely used plasticizers in polyvinyl chloride (PVC) products. Both evaluations concluded that, under current usage practices, these chemicals pose no unreasonable risks to consumers, the general population, or the environment.

Regulatory Context

The EPA’s evaluations were conducted in response to voluntary requests from manufacturers under the Toxic Substances Control Act (TSCA). Through the Manufacturer Requested Risk Evaluation (MRRE) process, producers of DINP and DIDP—represented by the American Chemistry Council (ACC)—submitted petitions in 2019. The EPA approved both requests and released draft risk assessments in May and August 2024, incorporating public comments and peer review feedback from the Scientific Advisory Committee on Chemicals (SACC).

Key Findings

DIDP Assessment (January 10, 2025): 99% of Production Uses Deemed Safe

• Safe Applications: 43 out of 49 industrial/commercial/consumer uses (99% of U.S. production) were deemed safe, including PVC films, textiles, building insulation, non-spray coatings, and sealants.
• Identified Risks: Limited to 6 high-concentration spray coating scenarios (≤1% of U.S. production), posing potential risks to unprotected female workers of childbearing age.

DINP Assessment (January 16, 2025): 97% of Production Uses Cleared

• Safe Applications: 28 out of 32 industrial/commercial uses and all 15 consumer uses (97% of production) showed no unreasonable risks, covering resilient flooring, automotive parts, water supply pipes, and non-spray coatings.
• Identified Risks: 4 unprotected spray adhesive/coating operations flagged for worker exposure concerns.

Industry Response

While acknowledging the scientific rigor of the EPA’s assessments, the ACC raised two key critiques:

• Operational Realism Gap: The EPA’s assumption of “unprotected operations” conflicts with industry-wide automation practices and mandatory personal protective equipment (PPE) protocols.
• Toxicological Threshold Dispute: For DINP’s potential developmental effects on male reproductive systems (phthalate syndrome), the ACC emphasized that real-world exposure levels are 1,000-fold lower than rodent study thresholds, far below risk thresholds.

The ACC urged the EPA to prioritize existing industry safety practices in future risk management rules, avoiding overly restrictive policies based on theoretical models.

Next Steps

Under TSCA, the EPA must issue final rules within two years if unreasonable risks are identified. The agency will now initiate rulemaking for DIDP and DINP, with proposals expected by 2027 to address worker protection measures.

Conclusion

The completion of these assessments marks a new equilibrium between industry and regulators in chemical safety management. Balancing technological innovation, commercial interests, and public health remains a central challenge for global chemical regulation.

About CIRS

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Further Information

1. Risk Evaluation for Diisononyl phthalate (1,2-Benzene- dicarboxylic acid, 1,2- diisononyl ester) (DINP) | US EPA
2. Risk Evaluation for Di-isodecyl phthalate (1,2-Benzene- dicarboxylic acid, 1,2- diisodecyl ester) (DIDP) | US EPA
3. ACC’s High Phthalates Panel Statement on EPA’s Final Risk Evaluation for DINP Under TSCA - American Chemistry Council
4. ACC’s High Phthalates Panel Statement on EPA’s Final Risk Evaluation for DIDP Under TSCA - American Chemistry Council