EPA Finalizes Risk Evaluation for Diisodecyl Phthalate DIDP

On January 3, 2025, the U.S. Environmental Protection Agency (EPA) released its final risk evaluation for diisodecyl phthalate (DIDP), concluding that it poses an unreasonable risk to human health, particularly to unprotected female workers of reproductive age who use spray products such as adhesives, paints, and coatings. The main concern is DIDP's potential to cause developmental toxicity, along with liver damage.  

DIDP is commonly used as a plasticizer in PVC, building materials, and automotive products, but EPA did not assess risks for uses exempted from TSCA, such as cosmetics, medical devices, and food contact materials (FCMs). 

DIDP Uses and Associated Risks  

EPA conducted a risk evaluation of DIDP at the manufacturer’s request under TSCA and approved it in 2019. During manufacture or used, DIDP can be released into water, settling in sediment or into the air where it attaches to dust particles. Indoors, DIDP can be released from products over time and adhere to dust, posing risks if inhaled or ingested. 

The evaluation found that DIDP poses a risk of developmental toxicity and liver damage, but did not find sufficient evidence of a cancer risk or male reproductive system harm, known as "phthalate syndrome.". Therefore, DIDP is excluded from the cumulative risk analysis for other phthalates linked to phthalate syndrome. 

Workers at Risk from Spray-Applied DIDP Products 

EPA identified an unreasonable risk of injury to female workers of reproductive age exposed to DIDP in six conditions of use, particularly from spray-applied products such as adhesives, sealants, paints, and coatings, which can create high concentrations of DIDP mist. This exposure represents about 1% of U.S. DIDP production. However, EPA found no unreasonable risks to consumers, the general population, or the environment. 

Regulatory Scope and Next Steps 

Uses not covered by TSCA, such as in food additives and cosmetics, were not evaluated by the EPA. Although past assessments suggest that dietary exposure is the primary risk from DIDP for certain groups, EPA's findings cannot be applied to uses of DIDP not covered by TSCA. 

Additional Information  

The list of conditions that contribute significantly to unreasonable risk are available here: 

EPA Finalizes TSCA Risk Evaluation for Diisodecyl Phthalate (DIDP) | US EPA