Apparent Half-Lives of Chlorinated-Perfluorooctane Sulfonate and Perfluorooctane Sulfonate Isomers in Aviation Firefighters

Elevated levels of perfluorooctane sulfonate (PFOS) and elevated detection frequency of chloro-substituted PFOS have been reported in Australian firefighters with historical exposure to aqueous-film forming foam (AFFF). The aim of this study is to estimate the apparent half-lives of Cl–PFOS and PFOS isomers in firefighters following the end of exposure to 3M-AFFF. Paired serum samples from 120 firefighters, collected approximately five years apart, were analyzed for 8-Cl–PFOS (8-chloroperfluoro-1-octanesulfonic acid) and PFOS isomers via targeted LC–MS/MS. Apparent half-life was estimated by assuming a first order-elimination model. Cl–PFOS was detected in 93% of all initial serum samples (