Increasing levels of long-chain perfluorocarboxylic acids (PFCAs) in Arctic and North Atlantic marine mammals, 1984-2009

► In general levels of long-chained PFCAs increased between 1984 and 2009. ► In general levels of PFOS were steady or decreasing. ► A change in PFOS exposure to ringed seals were indicated by analyzing structural isomers.