Book excerpt: This report describes a screening study of in all ninety-nine conventional and emerging per- and polyfluoroalkyl substances (PFASs) in the Nordic environment. In addition, extractable organic fluorine (EOF) was analysed. The latter can provide the amount, but not identity, of organofluorine in the samples, which in turn can be used to assess the mass balance between known and unknown PFASs. The study was initiated by the Nordic Screening Group and funded by these and the Nordic Council of Ministers through the Chemicals Group.A total of 102 samples were analyzed in this study, including bird eggs, fish, marine mammals, terrestrial mammals, surface water, WWTP effluents and sludge, and air. Samples were collected by institutes from the participating countries and self-governing areas; Denmark, Faroe Islands, Finland, Greenland, Iceland, Norway, and Sweden.