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IARC Assesses The Carcinogenicity of PFOS and PFOA

The IARC recently conducted a working group to evaluate evidence regarding the carcinogenicity of two well-known and well-regulated PFAS: PFOA and PFOS.

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December 12, 2023

By Krystal Spickler, program manager, Supply Chain team, UL Solutions

In November 2023, the World Health Organization’s (WHO) cancer agency, the International Agency for Research on Cancer (IARC) brought together a collective of experts originating from 11 countries in Lyon, France. The objective, as part of the IARC Monographs meetings, was to finalize an evaluation of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) for human carcinogenicity. PFOA and PFOS are two out of many chemicals included in the per- and polyfluoroalkyl substances (PFAS) class but are well-studied and have been subject to periodic regulatory action. Both substances are present in the environment and found in consumer products like cookware, clothing, and cosmetics, in addition to non-product applications.

A cancer hazard evaluation was conducted through reviewing published literature. PFOA was determined to be carcinogenic to humans (Group 1) based on “sufficient evidence of cancer in experimental animals and strong mechanistic evidence (for epigenetic alterations and immunosuppression) in exposed humans.” A handful of other carcinogenic characteristics were identified as well, including limited evidence for renal cell carcinoma and testicular cancer. PFOS received a group 2B classification, identifying it as possibly carcinogenic to humans. The basis for this classification included strong mechanistic evidence, including in exposed humans, along with other indicators of carcinogenicity. Limited evidence for cancer in experimental animals and inadequate evidence for cancer in humans was found.

Though the group’s full analysis will not be published until 2024 as Volume 135 of the IARC Monographs, a summary of the work is currently available in the journal The Lancet Onocology.


IARC Monographs evaluate the carcinogenicity of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) – IARC

The Lancet Oncology Journal - Assessment Summary

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