EPA recently released two documents regarding cumulative risk assessments under TSCA section 6, Draft Proposed Principles of Cumulative Risk Assessment Under the Toxic Substances Control Act, and Draft Proposed Approach for Cumulative Risk Assessment of High-priority Phthalates and Manufacturer-Requested Phthalate under the Toxic Substances Control Act. The first document details a set of principles for evaluating the cumulative risk of substances under TSCA; the second document presents a proposed approach for applying those principles to the evaluation of the cumulative risk posed by certain phthalate chemicals which are currently undergoing TSCA section 6 risk evaluation.
In the Draft Proposed Principles of Cumulative Risk Assessment Under TSCA, EPA explained that it plans to alter its approach to individual substance evaluations under TSCA section 6 by taking a cumulative assessment approach when appropriate. Previously, the Agency looked at the risks posed by a single substance under its specific conditions of use. The Agency now intends to implement a new approach to evaluating human health effects, which it believes is more appropriate when considering human exposure to these substances. People are often exposed to many chemical substances with similar effects at the same time, and looking at the combined exposure health risk will paint a more complete picture. The Agency believes that this approach will allow for more effective mitigation of identified unreasonable risks and provide particularly useful information for communities that face higher than normal levels of chemical pollution.
Phthalates will be subjected to a cumulative risk assessment because the group of substances has similar effects on human health and has generally been found concurrently in the human body. The phthalates to be assessed as a group include DEHP, BBP, DBP, DIBP, DCHP, DINP, and DIDP. The chemical group is often used in industrial and consumer products to make plastics more flexible and durable. The draft proposal requests comment and peer review on its assessment that six phthalate substances are toxicologically similar, and the U.S. population is frequently co-exposed to these substances, making a cumulative risk assessment the most appropriate course of review action under TSCA.
The Agency is accepting comments on these documents through April 28, 2023.