Risk Evaluation for Di-isodecyl phthalate (1,2-Benzene- dicarboxylic acid, 1,2- diisodecyl ester) (DIDP)

In December 2024, EPA released the risk evaluation under the Toxic Substances Control Act (TSCA) for di-isodecyl phthalate (1,2-Benzene- dicarboxylic acid, 1,2- diisodecyl ester) (DIDP) for public comment and peer review. EPA granted the manufacturer request for risk evaluation for DIDP in December 2019.

Learn more about manufacturer-requested risk evaluations.

Find other information about other chemicals undergoing risk evaluations under TSCA.

On this page:

Risk Evaluation Findings
Background on DIDP
Uses of DIDP
Recent Activities and Opportunities for Public Comment
Draft Risk Evaluation and Supporting Documents

Risk Evaluation Findings

EPA has determined that DIDP poses unreasonable risk of injury to human health to female workers of reproductive age exposed to the chemical. EPA did not identify risk of injury to human health for consumers or the general population or the environment that would significantly contribute to the unreasonable risk determination for DIDP.

EPA has determined that six of the 49 conditions of use of DIDP that are subject to TSCA significantly contribute to the unreasonable risk to workers. EPA found that female workers are at risk if they are unprotected from the DIDP contained in spray adhesives and sealants; paints and coatings; lacquers, stains, varnishes, and floor finishes; or penetrants and inspection fluid that contain DIDP because spraying these products could create high concentrations of DIDP in mist that an unprotected worker could inhale.

The human health hazard that EPA identified as having the strongest evidence to support this risk evaluation is developmental toxicity, which means that laboratory animals dosed with DIDP had litters where more rodent offspring died than was the case with the litters of rodents that were not dosed with DIDP. As the most sensitive health effects of concern relate to exposure of the developing fetus during gestation the population to which this risk determination is most relevant is female workers of reproductive age. DIDP can cause developmental toxicity and liver damage, but EPA determined that the evidence is not strong enough to conclude that it can cause cancer in people. EPA also did not find evidence to determine that DIDP affects male development and production, known as “phthalate syndrome.” Therefore, EPA is not including DIDP in its cumulative risk assessment for six other phthalates that do demonstrate effects consistent with phthalate syndrome, which will be released in early 2025.

EPA did not evaluate uses and potential exposure pathways that are not by statute covered by TSCA, such as food additives or cosmetics. Past assessments, including the U.S. Consumer Product Safety Commission’s risk assessment found that DIDP exposure comes primarily from diet for women, infants, toddlers, and children. While it is possible that DIDP 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 DIDP that are not subject to TSCA, and that EPA did not evaluate.

Background on DIDP

DIDP is a common chemical name for the category of chemicals that includes the following substances: 1,2-benzenedicarboxylic acid, 1,2-diisodecyl ester and 1,2-benzenedicarboxylic acid, di-C9-11-branched alkyl esters, C10-rich. The primary use for DIDP is as a plasticizer in plastic and rubber products. Information from the 2016 Chemical Data Reporting (CDR) for DIDP indicates the reported production volume is between 100 million and 270 million lbs/year (domestic manufacture including import).

Uses of DIDP

In the final scope of the DIDP risk evaluation, EPA identified conditions of use regulated under TSCA associated with the importing; processing; distribution in commerce; industrial, commercial and consumer uses; and disposal of DIDP, including:

As a plasticizer in polyvinyl chloride (PVC);
In building and construction materials;
In automotive articles; and
In other industrial. commercial, and consumer products, including adhesives and sealants, paints and coatings, electrical and electronic products, and other plastic and rubber products.

The above listed conditions of use are ways that a person or the environment could be potentially exposed to DIDP. However, when conducting a risk evaluation, EPA also considers the hazards (i.e., health effects or environmental impacts) that could occur from coming in contact with a chemical.

There are other uses of DIDP that do not fall under TSCA, such as food, food additives, drugs, cosmetics, and devices.

Recent Activities and Opportunities for Public Comment

In May 2024, EPA released the draft risk evaluation for DIDP for public comment and peer review. EPA accepted public comments on the draft risk evaluation for 60 days following publication in the Federal Register via docket EPA-HQ-OPPT-2024-0073 at www.regulations.gov.

EPA held a virtual peer review public meeting of the Science Advisory Committee on Chemicals (SACC) to discuss the draft risk evaluation from July 30-August 2, 2024. EPA also held a virtual preparatory 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. View the SACC website for more information on these meetings.

In August 2021, EPA published the final scope document outlining the hazards, exposures, conditions of use, and the potentially exposed or susceptible subpopulations the agency expects to consider in its risk evaluation. The agency released the draft scope in November 2020 and took public comments on the draft document.

As EPA continues to move through the risk evaluation process there will be additional opportunities for public comment. In addition to multiple public comment periods, EPA will continue to engage with stakeholders as it develops the risk evaluation. Stakeholders should reach out to EPA via the staff contact to engage with the agency.

Risk Evaluation and Supporting Documents

Read the Federal Register notice.

View the supporting documents in docket EPA-HQ-OPPT-2018-0435.