The Environmental Protection Agency (EPA) has conducted a detailed review of the risk assessments for two widely used phthalates, Di-isodecyl Phthalate (DIDP) and Di-isononyl Phthalate (DINP), as part of its ongoing evaluation of chemical safety. The assessments were discussed during a virtual meeting held from July 30 to August 1, 2024, where the Science Advisory Committee on Chemicals (SACC) evaluated the potential hazards posed by these chemicals in consumer products, indoor dust, and environmental exposure scenarios.
Overview of Risk Assessments
The EPA's review of DIDP and DINP is part of its mandate under the Toxic Substances Control Act (TSCA). Phthalates, including DIDP and DINP, are commonly used as plasticizers in a variety of consumer products such as vinyl flooring, automotive interiors, and children's toys. The risk evaluations aimed to determine the exposure risks from these chemicals, focusing on human health and environmental impact.
Concerns Raised by the SACC
During the virtual meeting, the SACC raised concerns about the methodology used in the assessments, particularly around exposure scenarios that may have been omitted or underestimated. For DIDP, the committee noted that the assessment failed to fully account for long-term exposure in certain environments, such as vehicle interiors and distribution centers, where workers may come into contact with phthalate-laden dust.
Impact on Vulnerable Populations
Another key issue identified was the potential exposure risks to vulnerable populations, including children and communities living near industrial or distribution hubs. The SACC emphasized the need to consider cumulative exposure from multiple sources of phthalates, including ingestion, inhalation, and dermal contact.
Environmental Exposure
The EPA's environmental assessment for DIDP raised concerns over the accuracy of predicted concentrations in water bodies. The committee noted that some of the modeled concentrations of DIDP in surface water exceeded its water solubility by over 60,000 times, highlighting the potential for overestimation. The lack of U.S.-based environmental monitoring data was also flagged as a significant gap in the assessment.
Recommendations for Refinement
The SACC suggested several refinements to improve the transparency and reliability of the risk evaluations. These include obtaining more robust data on phthalate concentrations in various environments, expanding exposure scenarios, and utilizing updated probabilistic models for more accurate risk assessment. The committee also recommended further research into the potential cumulative effects of exposure to multiple phthalates.
The EPA's review of DIDP and DINP is ongoing, with the SACC's recommendations likely to shape future evaluations. As the agency continues its work under TSCA, the focus on vulnerable populations and environmental impact will remain critical in ensuring the safe use of phthalates in everyday products.
