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On March 19, 2021, the California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) stated an intent to list perfluorooctanoic acid (PFOA) as carcinogenic under Proposition 65 (OEHHA, 2021a). PFOA was listed as a developmental toxicant under Proposition 65 in 2017. OEHHA since determined that PFOA also meets the criteria for listing as a carcinogen based on the National Toxicology Program (NTP) 2020 report NTP Technical Report on the Toxicology and Carcinogenesis Studies of Perfluorooctanoic Acid Administered in Feed to Sprague Dawley Rats (OEHHA, 2021a; NTP, 2020). The NTP study concluded that there was “clear evidence of carcinogenic activity” based on liver tumors (predominately hepatocellular adenomas) and pancreatic tumors (predominately acinar cell adenomas) in rats. According to OEHHA (2021), the NTP report constitutes a formal carcinogenicity identification by an authoritative body (OEHHA, 2021a; NTP, 2020).

While PFOA is no longer produced in the United States, its environmental persistence alongside the breakdown of other per- and polyfluoroalkyl substances create opportunities for continued PFOA exposure (OEHHA, 2021a).

Comments regarding PFOA and the data regarding its carcinogenicity must be received by OEHHA by May 3, 2021 (OEHHA, 2021a).

Updates on other PFAS under Proposition 65

Additionally, on March 26, 2021, OEHHA issued two notices of selection for perfluorooctane sulfonate (PFOS) and its salts and transformation and degradation precursors, and for perfluorodecanoic acid (PFDA), perfluorohexanesulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and perfluoroundecanoic acid (PFUnDA) and each of its salts for possible listing under Proposition 65 (OEHHA, 2021b). PFOS is currently listed under Proposition 65 as a developmental toxicant, and was selected in 2020 as one of the seven chemicals prioritized by the by the Carcinogen Identification Committee (CIC) for potential listing as a carcinogen (OEHHA, 2021b; OEHHA, 2021c). The other nominated PFAS will be reviewed by the Developmental and Reproductive Toxicant Identification Committee (DARTIC).

The notice for these PFAS initiates the 45-day data call-in period during which the public can submit relevant information regarding the carcinogenicity of these per- and polyfluoroalkyl substances (PFAS) (OEHHA, 2021b). Information will be accepted until Monday, May, 10, 2021, and will be considered as OEHHA develops the hazard identification materials for these PFAS (OEHHA, 2021b).

Other Agencies’ Evaluations of the Carcinogenic Hazards of PFAS 

Health agencies differ in their conclusions regarding PFAS’ potential carcinogenicity in humans. While the EPA concluded there is “suggestive evidence of carcinogenic potential” for PFOS and PFOA based on animal evidence and epidemiological studies of highly exposed populations, it considered the non-cancer health advisories for drinking water as protective of cancer, and has not developed an oral slope factor for either substance (US EPA, 2016a; US EPA, 2016b; Wisconsin Department of Health Services, 2019). In an evaluation of human health risks related to the presence of per- and polyfluoroalkyl substances in food, the European Food and Safety Authority (EFSA) concluded that there was “insufficient support for carcinogenicity of PFOS and PFOA in humans” (EFSA CONTAM Panel, 2020). Finally, the International Agency for Research on Cancer (IARC) has not evaluated the carcinogenic potential of PFOS, but has classified PFOA as “possibly carcinogenic to humans” based on “limited evidence” of carcinogenicity in both humans and animals (IARC 2008).

These varying conclusions indicate that further evaluation of the carcinogenicity of PFAS, including PFOA and PFOS, is warranted.

Cardno ChemRisk has assisted companies in understanding potential product exposures and health risks. Our scientists have evaluated diverse scenarios for Proposition 65 compliance, ranging from a single product to entire product lines, and have extensive professional experience evaluating the possible hazards posed by chemicals such as PFAS. Please visit Cardno ChemRisk’s Proposition 65 and PFAS pages for more information regarding our capabilities.

For an evaluation of health-based federal and state PFOA drinking water guidelines in the United States, please visit this publication by ChemRisk scientists.