PFAS carcinogenicity levels raised by IARC experts: PFOA and PFOS deemed more dangerous

A group of 30 scientists representing 11 countries convened at the International Agency for Research on Cancer (IARC) to reassess the hazardous nature of some Per- and Polyfluorinated Substances (PFAS). A summary of their evaluation, published in Lancet Oncology, revealed that perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), along with their isomers and salts, have been classified with higher levels of carcinogenicity. The detailed assessment will be published in 2024 as Volume 135 of the IARC Monographs.  

During the Monographs program, held from 7th to 14th November in Lyon, France, the working group meticulously reviewed extensive published literature on forever chemicals. As a result, PFOA was classified as a human carcinogen (Group 1), while PFOS was categorized as possibly carcinogenic to humans (Group 2B).

Previously, in 2014, IARC had only considered PFOA as a possible human carcinogen. However, it has now been elevated to the status of "carcinogenic to humans" (Group 1) due to "sufficient" evidence of cancer in experimental animals and "strong" mechanistic evidence in exposed humans. The evidence of cancer in experimental animals was deemed "sufficient", which observed an increased incidence of a suitable combination of benign and malignant neoplasms in both sexes of a single species. In exposed humans, strong mechanistic evidence was found, as PFOA was found to induce epigenetic alterations and exhibit immunosuppressive properties. Limited evidence of cancer in humans was noted regarding renal cell carcinoma and testicular cancer.    

As for PFOS, it has been classified as "possibly carcinogenic to humans" (Group 2B) based on strong mechanistic evidence. Evidence of cancer in experimental animals was deemed "limited," while evidence of cancer in humans was considered "inadequate."    

PFOA and PFOS are pervasive in the environment, even reaching remote areas. They have been detected in various products, including food packaging, carpets, building materials, cosmetics, cookware, waterproof clothing, and firefighting foams, among others. Drinking water supplies, especially near production or extensive use sites, have also been found to contain PFOA and PFOS. Workers involved in the production or direct use of these chemicals are expected to experience higher exposures, primarily through inhalation.  

The general population is primarily exposed to PFOA and PFOS through food and drinking water, and potentially through consumer products. In areas with contamination, drinking water becomes the main source of exposure for the general population, one example is the region of Veneto in Italy. Here, citizens' groups and associations, and local politicians welcomed the study, considering it as further confirmation of the dangers associated with PFAS.    

Philippe Grandjean, a professor of Environmental Medicine at the University of Southern Denmark, Boston University, and Harvard, who also served as a consultant in the ongoing trial in Veneto region concerning water poisoning and associated issues, expressed his views on the dangers of PFAS prior to the IARC study's publication.
According to Grandjean, substantial documentation now demonstrates a clear association between PFAS exposure and adverse effects on human health, particularly at high levels, such as those observed in Veneto's "red zone."
The expert also highlighted a calculation error made by the European Food Safety Authority (EFSA) in 2020, which established a tolerable weekly intake of the sum of four PFAS at a level he considered erroneously high. In contrast, the United States Environmental Protection Agency recommended exposure limits a hundred times lower than those of EFSA. Prof. Grandjean emphasized that evaluating cumulative PFAS exposure in the body cannot solely rely on blood concentrations, as these pollutants accumulate in organs and tissues. Due to their persistence and long-term effects, Grandjean likened PFAS to asbestos, an even more apt comparison now that these forever chemicals have been officially recognized as carcinogenic.    

The IARC's recent findings shed further light on the potential risks associated with PFOA and PFOS, reinforcing the need for continued research and regulation to protect public health and minimize exposure to these harmful substances.    

 

Source:  

The Lancet Oncology