From the publication:

Per- and polyfluoroalkyl substances (PFAS), previously referred to as “perfluorinated compounds”, are a class of manufactured chemicals that have been detected in nearly all sampling of geographic locations and environmental matrices worldwide, including sites that had no nearby manufacture or use of PFAS. PFAS are used in hundreds of industrial and consumer products including food packaging and waterproof/stain resistant fabrics. Their strong carbon-fluorine bonds provide both hydrophobic and oleophobic properties, which make these chemicals extremely persistent in the environment. The class of PFAS includes tens of thousands of potential environmental contaminants including over one thousand chemicals previously or currently approved for use in the U.S..

For PFAS measured at concentrations already found in the general population, exposure may suppress the immune system. Additionally, exposure to PFAS, with most studies on PFOA and PFOS, has been associated with many health harms, including an increased risk of cancer, high cholesterol, thyroid disease, and reproductive and developmental harms.

The median level of total targeted PFAS in fish fillets from rivers and streams across the United States was 9,500 ng/kg, with a median level of 11,800 ng/kg in the Great Lakes. PFOS was the largest contributor to total PFAS levels, averaging 74% of the total. The median levels of total detected PFAS in freshwater fish across the United States were 278 times higher than levels in commercially relevant fish tested by the U.S. Food and Drug Administration in 2019–2022. Exposure assessment suggests that a single serving of freshwater fish per year with the median level of PFAS as detected by the U.S. EPA monitoring programs translates into a significant increase of PFOS levels in blood serum.

Additional information:

In June 2018, the Agency for Toxic Substances and Disease Registry (ATSDR) released a draft Toxicological Profile that derived minimal risk levels (MRLs), which are similar to RfDs, for intermediate duration exposure (15–364 days) of four PFAS routinely measured in NHANES [28]. The MRL [minimal risk levels] values for PFOA (3 ng/kg/day) and PFOS (2 ng/kg/day) are 6.7 and 10 times lower than the RfDs EPA used to develop its 2016 HAs and similar to those developed by New Jersey, though they are based on different studies and endpoints. View full publication