IARC Publishes Monograph on Two PFAS
The International Agency for Research on Cancer (IARC) in February published volume 135 of its monograph series, which evaluates the carcinogenicity of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), and their corresponding isomers and salts. PFOA and PFOS are both per- and polyfluoroalkyl substances, also known as PFAS, and are “extremely resistant to degradation,” according to IARC.
PFOA has a wide range of uses, such as in surface coatings intended to make certain household products, carpets, textiles, leather products, and food packaging resistant to stains, oil, and water. Other uses include in fluoropolymer manufacture and applications, in electrics and electronics, and in construction materials, the agency notes. IARC’s monograph classifies PFOA as Group 1, carcinogenic to humans, due to “the combination of sufficient evidence for cancer in experimental animals and strong mechanistic evidence of key characteristics of carcinogens in exposed humans.”
PFOS, which has some similar uses to PFOA, falls into Group 2B and is possibly carcinogenic to humans, according to IARC. While there is “strong evidence that PFOS exhibits multiple key characteristics of carcinogens in exposed humans,” IARC found only “limited evidence” that it causes cancer in experimental animals and “inadequate evidence” for its carcinogenicity in humans. According to the agency, PFOS is used in aqueous film-forming foams for firefighting as well as in insulation, dyes, and ink. It is also used to make imaging devices and semiconductors, and in photolithography and electroplating.
Workers exposed to PFOA and PFOS include those who produce and use fluorochemicals and firefighters. According to NIOSH, ski wax technicians are also known to be exposed more than the general U.S. population.
An infographic accompanying the monograph explains that current uses of PFOA and PFOS are limited by the Stockholm Convention, a global treaty intended to protect human health and the environment from these and other persistent organic pollutants, and other regulations. The Stockholm Convention was adopted in 2001, entered into force in 2004, and today there are 186 parties to the convention. The U.S. signed the convention in 2001 but has not ratified it “because we currently lack the authority to implement all of its provisions,” according to the Department of State website.
A U.S. EPA rule that went into effect in July 2024 designates both PFOA and PFOS, including their salts and structural isomers, as hazardous substances under CERCLA, the Comprehensive Environmental Response, Compensation, and Liability Act, which is also known as Superfund. The chemicals’ designation as CERCLA hazardous substances means that entities responsible for PFOA and PFOS must inform federal, state, and local authorities of any release of these chemicals that meets or exceeds the “reportable quantity” of one pound in a 24-hour period.
“The latest science is clear: exposure to PFOA and PFOS over long periods of time can result in significant health risks,” an EPA webpage with questions and answers about the CERCLA designation states. “If not addressed, PFOA and PFOS will continue to migrate, further exacerbating exposure risk and potential cleanup costs.”
The new volume of the IARC monographs series is available from the agency’s website. Additional information can be found in an IARC news article.
Related: An article published in the March 2022 issue of The Synergist focuses on the challenges in researching and managing exposure to PFAS. Another article published later that year explores how PFAS complicate product stewards' efforts to plan ahead.
