EPA Releases Draft TSCA Risk Evaluation for DCHP, Draft Cumulative Risk Analysis for Phthalates, and Draft Hazard Technical Support Documents for DIBP, DBP, DEHP, and BBP

Released January 6, 2024

Today, the U.S. Environmental Protection Agency (EPA) released its draft risk evaluation and associated technical support documents for dicyclohexyl phthalate (DCHP) under the Toxic Substances Control Act (TSCA) for public comment. In the draft risk evaluation, EPA preliminarily determined that DCHP presents an unreasonable risk of injury to human health for workers from inhalation exposure. Among other possible effects, exposure to DCHP can harm the developing male reproductive system both individually and cumulatively with exposure to other phthalates, in a phenomenon known as “phthalate syndrome” (e.g., decreased fetal testicular testosterone, male reproductive tract malformations, male nipple retention, and decreased male fertility).   

EPA is also releasing two draft cross-phthalate technical support documents related to cumulative risk analysis for benzyl butyl phthalate (BBP), dibutyl phthalate (DBP), di(2-ethylhexyl) phthalate (DEHP), diisobutyl phthalate (DIBP), and di-isononyl phthalate (DINP), and a dozen draft technical support documents that will be relied upon in the risk evaluations for  BBP, DBP, DEHP, and DIBP. This follows the phthalates documents release schedule laid out by EPA on December 10th. 

Draft Risk Evaluation for DCHP 

DCHP is used primarily as a plasticizer or stabilizing agent in polyvinyl chloride (PVC) products and in adhesives, sealants, paints, coatings, rubbers, and other applications. EPA preliminarily determined that DCHP presents an unreasonable risk of injury to human health for workers. Nine conditions of use significantly contribute to the unreasonable risk to workers. EPA preliminarily shows that DCHP does not pose unreasonable risk to the environment, the general population, or consumers.  There are other uses of DCHP that are generally excluded from TSCA’s definition of chemical substance, such as food contact materials, and EPA did not evaluate risk associated with these uses. As such, the conclusions in this draft risk evaluation cannot be extrapolated to form conclusions about uses of DCHP that are not subject to TSCA, and that EPA did not evaluate. 

Workers may be exposed to DCHP when making products or otherwise using DCHP in the workplace. When it is manufactured or used to make products, DCHP can be released into the water where most of it will end up in the sediment at the bottom of lakes and rivers. If released into the air, DCHP will attach to dust particles and be deposited on land or into water. Indoors, DCHP 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 DCHP.  

Read the draft risk evaluation for DCHP.   

Cross-phthalate Cumulative Risk Analysis  

EPA has conducted a cumulative risk analysis of BBP, DBP, DEHP, DIBP, DCHP, and DINP in similar fashion as the U.S. Consumer Product Safety Commission, the National Academies of Sciences, Engineering, and Medicine (NASEM), and Health Canada have previously done. EPA and others conducted cumulative risk analysis because of phthalates’ widespread use in industrial and consumer products, which results in people being exposed to many phthalates that all cause the same adverse health effect at once. Laboratory animal studies have demonstrated that prenatal exposures to rodents to each of these chemicals results in an adverse developmental effect called phthalate syndrome. In the cumulative risk analysis, EPA used data from the Center for Disease Control’s National Health and Nutrition Examination Survey to estimate cumulative risk that people face from being exposed to multiple phthalates. EPA has incorporated this analysis into the DCHP draft risk evaluation, since it represents the best available science, and plans to do the same in support of the subsequent individual draft chemical risk evaluations.  

Underlying both the cumulative risk analysis and the individual human health hazard technical support documents is the “Draft Meta Analysis and Benchmark Dose Modeling of Fetal Testicular Testosterone for BBP, DBP, DEHP, DIBP, and DCHP.” EPA’s approach was similar to that used by NASEM (2017) and included newly available phthalate syndrome -related information for these phthalates.  

Results from this analysis are used in the individual phthalate risk evaluations and human health hazard technical support documents and the phthalate cumulative risk analysis technical support document. The technical support document implements a relative potency factor (RPF) approach which relies on a common hazard outcome (i.e., reduced fetal testicular testosterone) across BBP, DBP, DEHP, DIBP, DCHP, and DINP. The RPF approach is commonly used in mixtures and cumulative risk analyses by EPA. For some chemicals, use of the RPF approach represents a more sensitive and robust endpoint than the individual chemical hazard value. The DCHP draft risk evaluation includes an example of the application of the RPF approach, which will also be included in the remaining four following phthalate risk evaluations. 

Technical Support Documents for DIBP, DBP, DEHP, BBP 

EPA is releasing the physical chemistry and environmental fate, human health non-cancer hazard, and environmental hazard technical support documents for DIBP, DBP, DEHP, and BBP. The physical chemistry and environmental fate and transport technical support documents describe the physical and chemical properties that will be used to estimate exposures and to characterize persistence and transport of the chemical when released to the environment. The human health non-cancer technical support documents identify non-cancer hazard values that will be used to estimate risks from exposures in the draft risk evaluations. The environmental hazard technical support documents identify the potential environmental hazards associated with exposures and the concentration of concern that will be used to estimate risks from exposures in the draft risk evaluations.     

Next Steps 

Upon publication of the Federal Register notice, EPA will accept public comments on the DCHP draft risk evaluation for 60 days via docket EPA-HQ-OPPT-2018-0504 on regulations.gov.  

EPA is also opening the chemical-specific dockets for DIBP, DBP, DEHP, and BBP for public comments, but the official 60-day public comment period for these chemicals will not begin until EPA releases the associated draft risk evaluations. For more information, view the phthalates documents release schedule laid out by EPA on December 10th. 

• DIBP: EPA-HQ-OPPT-2018-0434  
• DBP: EPA-HQ-OPPT-2018-0503  
• DEHP: EPA-HQ-OPPT-2018-0433 
• BBP: EPA-HQ-OPPT-2018-0501 

Read the draft risk evaluation for DCHP.  

Additional Information on DCHP 

Conditions of Use that Preliminarily Significantly Contribute to the Unreasonable Risk: 

• Manufacturing – Domestic manufacturing; 
• Processing – Incorporation into formulation, mixture, or reaction product – Adhesive and sealant chemicals in adhesive manufacturing;  
• Processing – Incorporation into formulation, mixture, or reaction product – Plasticizer (adhesive manufacturing; paint and coating manufacturing; and printing ink manufacturing);  
• Processing – Incorporation into formulation, mixture, or reaction product – Stabilizing agent (adhesive manufacturing; asphalt paving, roofing, and coating materials manufacturing; and paints and coating manufacturing); 
• Industrial Use – Finishing agent – Cellulose film production;  
• Industrial Use – Inks, toner and colorant products (e.g., screen printing ink); 
• Industrial Use – Paints and coatings;  
• Commercial Use – Inks, toner and colorant products (e.g., screen printing ink); and  
• Commercial Use – Paints and coatings. 

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

• Manufacturing – Importing; 
• Processing – Incorporation into article – Plasticizer in plastics product manufacturing and rubber product manufacturing;  
• Processing – Repackaging (e.g., laboratory chemicals);  
• Processing – Recycling; 
• Distribution in commerce; 
• Industrial Use – Adhesives and sealants (e.g., computer and electronic product manufacturing; transportation equipment manufacturing); 
• Industrial Use – Other articles with routine direct contact during normal use including rubber articles; plastic articles (hard) (e.g., transportation equipment manufacturing); 
• Commercial Use – Adhesives and sealants;  
• Commercial Use – Building/construction materials not covered elsewhere;  
• Commercial Use – Laboratory chemicals; 
• Commercial Use – Other articles with routine direct contact during normal use including rubber articles; plastic articles (hard); 
• Consumer Use – Adhesives and sealants; 
• Consumer Use – Other articles with routine direct contact during normal use including rubber articles; plastic articles (hard); 
• Consumer Use – Other consumer articles that contain dicyclohexyl phthalate from: inks, toner and colorants; paints and coatings; adhesives and sealants (e.g., paper products, textiles, products using cellulose film, etc.); and 
• Disposal.