PFAS – perfluoroalkyl and polyfluoroalkyl substances – are now either suspected or known to contribute to thyroid disease, elevated cholesterol, liver damage and cancer, among other health issues. They can be found in the blood of most Americans and in many drinking water systems, which is why the Environmental Protection Agency in April 2024 finalized the first enforceable federal limits for six types of PFAS in drinking water systems. The limits – between 4 and 10 parts per trillion for PFOS, PFOA, PFHxS, PFNA and GenX – are less than a drop of water in a thousand Olympic-sized swimming pools, which speaks to the chemicals’ toxicity. The sixth type, PFBS, is regulated as a mixture using what’s known as a hazard index.

https://theconversation.com/removing-pfas-from-public-water-systems-will-cost-billions-and-take-time-here-are-ways-you-can-filter-out-harmful-forever-chemicals-at-home-227670