Perfluorerte alkylerte stoffer (PFAS) - en litteraturstudie om PFAS i akvatiske miljø, effekter og kunnskapshull

Perfluorinated alkylated substances (PFAS) are organic fluorinated compounds of wide application in several industrial and commercial products, including fire fighting foam. Due to extensive use, persistence in the environment and bioaccumulative properties, these compounds have been detected in all environmental matrices, wildlife and humans. High levels of PFAS have also been detected in water and aquatic organisms in Norway such as fish. The environmental prevalence is a result of both deposition from atmospheric long range transport and local point sources of emissions of PFAS. Application of firefighting agents containing PFAS represents an important point source of PFAS emission to the environment from the fire training grounds at the Norwegian Armed Forces’ airbases. Concerns about the toxic properties of PFAS led to the phasing out of such compounds in firefighting foam. However, due to the persistency of PFAS, there are concerns regarding the prolonged effects in fish and other organisms in the aquatic recipients characterized by PFAS contamination originating from the previous use of firefighting foam as well as other sources. The present literature study addresses the properties, transport, sources and fate of PFAS in aquatic environment and organisms, in addition to PFAS precursors and degradation processes of these. The study also focuses on levels and potential toxic effects of PFAS in fish. Finally, possible passive sampling technologies to monitor aquatic levels of PFAS are reviewed. This report uncovers knowledge gaps in our understanding of the fate and effects of PFAS in the environment. In particular, degradation mechanisms of precursor compounds is an important area of further research, since there are clear indications of precursors being a key source of the presence of persistent PFAS in the environment. It is still the case that we know the most about the two most analyzed compounds perfluorooctane sulphonic acid (PFOS) and perfluorooctanoic acid (PFOA). These compounds will, however become less relevant due to the phasing out in the 2000s, and the replacement with other PFAS and precursor compounds. Furthermore, there is a need for greater understanding of the adverse effects, and the underlying mechanisms of the various PFAS. This knowledge gap is particularly prominent in relation to risk assessment and determination of critical values in environment and food items, due to the fact that such critical values only exist for PFOS and PFOA today. PFAS is a chemical group of very different physical and chemical properties, which does not enable them to be treated as a homogeneous group of chemicals. High PFAS concentrations are detected in particular places in water and fish near point sources. The environmentally relevant PFAS levels in surface water have not been demonstrated to be acute toxic to fish. Today, there are few, or no known examples of adverse effects on free ranging fish as a result of PFAS contamination in their natural habitat. Passive samplers may be a useful tool for semi quantitative or qualitative monitoring of PFAS levels in water, and they may be useful in comparing runoff from different sources in an aquatic recipient. Passive sampling technologies for PFAS are still under development, so that grab sampling remains the recommended method in measuring concentrations of PFAS in water.