Strand, J., Bossi, R., Sortkjær, O., Landkildehus, F. & Larsen, M.M. 2007. NERI Technical Report No. 608. 49 pp.
The study shows that the occurrence of several perfluorated alkylated substances (PFAS) and organotin compounds are widespread at point sources and in the aquatic environments in Denmark.
The fluorinated compounds PFOS and PFOA are generally the most dominating components of the measured PFAS in both the point sources and in the aquatic environment. Moreover five other PFAS have also been found in this study. PFAS were found both in the inflow and outflow water and the sewage fraction from municipal and industrial wastewater treatment plants (WWTPs), indicating that WWTPs can be significant sources to PFAS in the environment. This is also reflected in the locally elevated PFAS concentrations found in fish like eels (Anguilla anguilla) from shallow freshwater and marine areas. However, the highest PFAS concentration (156 µg/kg) found in fish in this study was in plaice (Pleuronectes platessa) from the Skagerrak, but it is unknown if this can be related to local sources.
Butyltin compounds like TBT, DBT and MBT are the most widespread organotin compounds at both point sources and in mussels and fish from the freshwater and the marine environments. The highest concentrations in the sewage treatment plants were found in inflow water and sewage and not so much in the outflow water, which show that the WWTPs generally have an efficient removal of organotin compounds from the outflow water. The occurrence of butyltin compounds including TBT in relatively high concentrations in sediment, mussel and biota from freshwater and marine environments may primarily be ascribed to the use of TBT as antifouling agent in paints for ships. In addition, a very high TBT concentration has also been found in drainage water from a former industrial area. Phenyltin compounds like triphenyltin are primarily found accumulated in freshwater and marine fish, but it is not known whether the main course is the former use of TPhT as agricultural fungicide or its use as antifouling agent in paints for ships. Octyltin compounds are only found in samples of inflow water and sewage from some of the analysed WWTPs.
It is assessed that the found concentration levels of the most toxic triorganotin compounds TBT and TPhT pose a risk to the aquatic environment and especially to organisms at the lower trophic levels of the food web. However, no surface water samples have been analysed in this study because the detection limit is above the EU proposal to environmental quality standard (EQS) at 0.2 ng/l for TBT, and sediment and biota are therefore regarded as a better matrix to assess the occurrence of organotin in the environment.
PFAS compounds also seem to pose an environmental risk, but to a higher degree to fish-eating birds and mammals at the higher trophic levels, because the PFOS concentration in most of the analysed fish samples was above the PNEC (predicted no effect concentration) level for secondary poisoning at 17 µg/kg in food. However, it has to be noticed that liver samples and not whole fish have been analysed in this study.
It is recommended that PFAS and organotin compounds are included in future monitoring programmes for point sources, freshwater and marine environments in Denmark.
Full report in pdf-format (1,095 kB).
