Science Alert  August 5, 2022 An international team of researchers (Sweden, Switzerland) hypothesized that environmental contamination by per- and polyfluoroalkyl substances (PFAS) defines a separate planetary boundary and that this boundary has been exceeded. They tested the hypothesis by comparing the levels of four selected perfluoroalkyl acids (PFAAs) in various global environmental media (i.e., rainwater, soils, and surface waters) with recently proposed guideline levels. On the basis of the test, the researchers concluded that (1) levels of PFOA and PFOS in rainwater often greatly exceed US EPA Lifetime Drinking Water Health Advisory levels and the sum of the four PFAAs […]