On March 26, the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment (OEHHA) gave notice of its selection of several per- and polyfluoroalkyl substances (PFAS) for review and possible listing under California's Proposition 65 (Prop 65). OEHHA published two separate notices for public comment:  one notice for perfluorooctane sulfonate (PFOS) and its salts and transformation and degradation precursors, and  another notice for perfluorodecanoic acid (PFDA), perfluorohexanesulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and perfluoroundecanoic acid (PFUnDA), as well as each of their salts. The public comment period for both notices closes on May 10, 2021.

Although PFOS, PFDA, PFHxS, PFNA, and PFUnDA are undergoing simultaneous review, OEHHA elected to publish two separate notices given that the chemicals will be reviewed by two different expert committees of OEHHA's Science Advisory Board: the Carcinogen Identification Committee (CIC) and the Developmental and Reproductive Toxicant Identification Committee (DARTIC).

While PFOS is already a listed substance under Prop 65 for reproductive toxicity, PFOS will undergo review by the CIC, which will make a determination as to whether PFOS has been clearly shown to cause cancer. The selection of PFOS for this review was previewed by the CIC's designation of PFOS as “high priority” for review at its  November 17, 2020 committee meeting. Meanwhile, PFDA, PFHxS, PFNA, and PFUnDA will undergo review by the DARTIC. Unlike the CIC, the DARTIC's main function is to render an opinion about whether a chemical has been clearly shown to cause reproductive toxicity. DARTIC selected these chemicals for review from a list of prioritized chemicals created at its  December 10, 2020 committee meeting.

While there are several additional steps that OEHHA must take prior to listing PFDA, PFHxS, PFNA, and PFUnDA under Prop 65 and adding a cancer designation for PFOS, these notices are a clear indication of California's intention to press forward with its regulation of additional PFAS under Prop 65. Although the listing process could take upward of another year to be finalized, it is highly likely — if not a foregone conclusion — that the noticed substances will be listed by their respective OEHHA Science Advisory Board committees.

Companies doing business in California should anticipate that any products containing these substances (including their salts and, in the case of PFOS, its transformation and degradation precursors) eventually will require compliance with Prop 65, including the obligation to provide a clear and reasonable warning to California residents prior to exposure and the drinking water discharge ban. Additionally — because salts and PFOS transformation/degradation precursors are now implicated by these notices — companies doing business in California should take special care to thoroughly screen their products for these additional substances and compounds, which may not easily appear to be associated with these PFAS substances at first glance.

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