The U.S. Environmental Protection Agency (EPA) will hold a virtual public preparatory meeting for the Science Advisory Committee on Chemicals (SACC) members, ad hoc reviewers, and the public to comment on and ask questions regarding the scope and clarity of the draft charge questions to be used for the May 8-11, 2023, review of two draft documents related to cumulative risk assessment under the Toxic Substances Control Act (TSCA). As reported in our March 1, 2023, memorandum, earlier this year, EPA released for public comment and peer review a set of principles for evaluating cumulative risks under TSCA and an approach for applying those principles to the evaluation of the cumulative risk posed by certain phthalate chemicals undergoing TSCA Section 6 risk evaluation.

• Draft Proposed Principles of Cumulative Risk Assessment under the Toxic Substances Control Act: The document discusses what cumulative risk assessment is and how it could be used in the scientific and regulatory context of TSCA. EPA notes that a cumulative risk assessment “will not always be the best approach, or possible to complete in the statutory timeframes provided for TSCA risk evaluations. But when chemicals are sufficiently similar toxicologically and are found to present co-exposures -- meaning people are . . .  exposed to multiple chemicals at the same time -- a cumulative risk assessment may be appropriate.”

• Draft Proposed Approach for Cumulative Risk Assessment of High-Priority Phthalates and a Manufacturer-Requested Phthalate under the Toxic Substance Control Act: The document describes a proposed methodology for evaluating cumulative risk for the phthalate chemicals currently under review. EPA proposes in its approach submitted for public comment and peer review that di-ethylhexyl phthalate (DEHP), butyl benzyl phthalate (BBP), dibutyl phthalate (DBP), di-isobutyl phthalate (DIBP), dicyclohexyl phthalate (DCHP), and di-isononyl phthalate (DINP) (but not di-isodecyl phthalate (DIDP)) are toxicologically similar (and pose an additive hazard) and that the U.S. population is co-exposed to these phthalates. Therefore, EPA proposes to group these phthalates for cumulative risk assessment under TSCA as described in the “Draft Proposed Approach” document. EPA notes that this proposed approach “is not itself a cumulative risk assessment nor does it make a finding of risk, but rather is a methodology that EPA proposes to use and seeks public input about and peer review on.”

Registration for the virtual preparatory meeting is open. To participate as a listen-only attendee, registration will be open up to the end of the meeting. Requests to make brief (up to five minutes) oral comments to the SACC during the preparatory meeting can be submitted when registering and will be accepted until April 21, 2023.

The two draft documents, draft charge questions, and other supporting materials are available online in docket EPA-HQ-OPPT-2022-0918. Written comments are due April 28, 2023, for distribution to SACC before the meeting.