EPA Finalizes TSCA Risk Evaluation for Diisodecyl Phthalate (DIDP)

Released January 3, 2025

Today, the U.S. Environmental Protection Agency (EPA) released the final risk evaluation for diisodecyl phthalate (DIDP) conducted under the Toxic Substances Control Act (TSCA). EPA has determined that DIDP presents an unreasonable risk of injury to human health, because unprotected female workers of reproductive age spraying adhesive, sealant, paint, and coating products that contain DIDP and are used on vehicles and building and construction materials could create high concentrations of DIDP in mist. The most sensitive health concern of DIDP is developmental toxicity, and if the Agency can protect against this, it would also protect all workers against other adverse effects such as liver toxicity.   

DIDP 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. There are other uses of DIDP that are generally excluded from TSCA, such as cosmetics, medical devices, and food contact materials, and EPA did not evaluate risk associated with these uses.  

Uses and Risks Associated with DIDP

EPA conducted the risk evaluation for DIDP at the manufacturer’s request. Under TSCA, manufacturers can request that EPA conduct risk evaluations on chemicals they manufacture. EPA received and granted this manufacturer request for a risk evaluation of DIDP in 2019.  

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 determine that DIDP causes cancer. EPA also did not find evidence to determine that DIDP affects the developing male reproductive system, known as “phthalate syndrome.” Therefore, EPA is not including DIDP in its cumulative risk analysis  for six other phthalates that do demonstrate effects consistent with phthalate syndrome, which will be released in early 2025. 

In the risk evaluation, EPA has determined that DIDP poses unreasonable risk of injury to human health when female workers of reproductive age are exposed to the chemical for six conditions of use (an increase from the one COU identified in the draft).  EPA received new information during public comment and peer review about how spray-applied phthalate containing products are used, and the health effects of those uses. 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 fluids. Spraying these products could create high concentrations of DIDP in mist that an unprotected worker could inhale. These uses represent approximately 1% of the DIDP production volume in the U.S. 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 DIDP.  

EPA 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 CPSC’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.  

Next Steps 

EPA will now begin the risk management process to address the unreasonable risk presented by DIDP. EPA will release a proposed rule under TSCA section 6 to protect workers from the identified risks.  

Read the final risk evaluation for DIDP. 

Additional Information 

Conditions of Use that Significantly Contribute to the Unreasonable Risk: 

• Industrial use – adhesives and sealants; 
• Industrial use – construction, paint, electrical, and metal products – paints and coatings; 
• Commercial use – construction, paint, electrical, and metal products – paints and coatings (including surfactants in paints and coatings); 
• Commercial use – construction, paint, electrical, and metal products – adhesives and sealants (including plasticizers in adhesives and sealants); 
• Commercial use – construction, paint, electrical, and metal products – lacquers, stains, varnishes, and floor finishes (as plasticizer); and 
• Commercial use – other uses – inspection fluid/penetrant. 

Conditions of Use that Do Not Significantly Contribute to the Unreasonable Risk: 

• Manufacturing – domestic manufacturing; 
• Manufacturing – importing; 
• Processing – incorporation into formulation, mixture, or reaction product – adhesives and sealants manufacturing; 
• Processing – incorporation into formulation, mixture, or reaction product – laboratory chemicals manufacturing; 
• Processing – incorporation into formulation, mixture, or reaction product – petroleum lubricating oil manufacturing; lubricants and lubricant additives manufacturing; 
• Processing – incorporation into formulation, mixture, or reaction product – surface modifier in paint and coating manufacturing; 
• Processing – incorporation into formulation, mixture, or reaction product – plastic material and resin manufacturing; 
• Processing – incorporation into formulation, mixture, or reaction product – plasticizers (paint and coating manufacturing; pigments; rubber manufacturing); 
• Processing – incorporation into formulation, mixture, or reaction product – processing aids, specific to petroleum production (oil and gas drilling, extraction, and support activities); 
• Processing – incorporation into formulation, mixture, or reaction product – other (part of the formulation for manufacturing synthetic leather); 
• Processing – incorporation into articles – abrasives manufacturing; 
• Processing – incorporation into articles – plasticizers (asphalt paving, roofing, and coating materials manufacturing; construction; automotive products manufacturing, other than fluids; electrical equipment, appliance, and component manufacturing; fabric, textile, and leather products manufacturing; floor coverings manufacturing; furniture and related product manufacturing; plastics product manufacturing; rubber product manufacturing; ink, toner, and colorant products manufacturing (including pigment); photographic supplies manufacturing; toys, playground, and sporting equipment manufacturing); 
• Processing – repackaging; 
• Processing – recycling; 
• Distribution in commerce; 
• Industrial use – abrasives; 
• Industrial use – functional fluids (closed systems); 
• Industrial use – lubricant and lubricant additives; 
• Industrial use – solvents (for cleaning and degreasing); 
• Commercial use – automotive, fuel, agriculture, outdoor use products– lubricants; 
• Commercial use – construction, paint, electrical, and metal products – building/construction materials (wire or wiring systems; joint treatment, fire-proof insulation); 
• Commercial use – construction, paint, electrical, and metal products – electrical and electronic products; 
• Commercial use – furnishing, cleaning, treatment/care products – furniture and furnishings; 
• Commercial use – furnishing, cleaning, treatment/care products – construction and building materials covering large surface areas including stone, plaster, cement, glass and ceramic articles; fabrics, textiles, and apparel (as plasticizer) (floor coverings (vinyl tiles, PVC-backed carpeting, scraper mats)); 
• Commercial use –packaging, paper, plastic, hobby products – ink, toner, and colorant products; 
• Commercial use – packaging, paper, plastic, hobby products – PVC film and sheet; 
• Commercial use –packaging, paper, plastic, hobby products – plastic and rubber products (textiles, apparel, and leather; vinyl tape; flexible tubes; profiles; hoses); 
• Commercial use – other uses – laboratory chemicals; 
• Commercial use – other uses – automotive articles; 
• Consumer use – automotive, fuel, agriculture, outdoor use products – lubricants; 
• Consumer use – construction, paint, electrical, and metal products – adhesives and sealants (including plasticizers in adhesives and sealants); 
• Consumer use – construction, paint, electrical, and metal products – building/construction materials covering large surface areas including stone, plaster, cement, glass and ceramic articles (wire or wiring systems; joint treatment); 
• Consumer use – construction, paint, electrical, and metal products – electrical and electronic products; 
• Consumer use – construction, paint, electrical, and metal products – paints and coatings; 
• Consumer use – furnishing, cleaning, treatment/care products – fabrics, textiles, and apparel (as plasticizer); 
• Consumer use – packaging, paper, plastic, hobby products – arts, crafts, and hobby materials (crafting paint applied to craft); 
• Consumer use – packaging, paper, plastic, hobby products – ink, toner, and colorant products; 
• Consumer use – packaging, paper, plastic, hobby products – PVC film and sheet; 
• Consumer use – packaging, paper, plastic, hobby products – plastic and rubber products (textiles, apparel, and leather; vinyl tape; flexible tubes; profiles; hoses); 
• Consumer use – packaging, paper, plastic, hobby products – toys, playgrounds, and sporting equipment; 
• Consumer use – other uses – automotive articles; 
• Consumer use – other – novelty articles, and 
• Disposal.