Risks and Effects of the dispersion of PFAS on Aquatic, Terrestrial and Human Populations in the vicinity of international airports.
RE-PATH is a five year research project financed by Swedavia Swedish Airports and the Foundation for the Swedish Environmental Research Institute (SIVL). The SIVL is funded by grants from the Swedish Research Council FORMAS and the Swedish Environmental Protection Agency. The aim with the project is to investigate the consequences of the use of PFOS containing fire fighting foams that were used for decades at airports airports in Sweden, and this study includes Stockholm Arlanda Airport and Gothenburg Landvetter Airport.
Perfluorooctane sulfonate (PFOS) is an extremely persistent and toxic compound that biomagnifies in biota due to its protein binding properties. One of the main areas of usage was in Aqueous Film Forming Foam (AFFF), a product which contained several perfluoroalkylated substances (PFAS). From the 27th of June 2011 it is not allowed to use fire fighting foams containing PFOS and both of the airports have used products free from PFOS the last years. Despite this, PFOS and other PFAS is still leaking out from the fire fighting training areas to the surrounding environment. Within RE-PATH sediment, surface water and fish has been sampled from the catchment areas of the two airports. The sampling has been performed each spring and fall since 2009 and different PFAS has been analysed. Also samples from reference lakes have been collected, i.e. from lakes where the contamination mainly origins from atmospheric deposition.
The results show that at both Stockholm Arlanda Airport and Gothenburg Landvetter Airport, there is a clear covariation between the concentrations of PFOS found in surface water and the distance to the fire fighting areas at the airports. The water concentrations in the recipient lakes Västra Ingsjön (Landvetter airport) and Lake Halmsjön (Arlanda airport), are much higher compared to the reference lakes, especially Lake Halmsjön which contain about 50 times higher levels. Also the fish (perch) in these two lakes contain higher PFOS levels compared to the perch from the reference lakes. It is only perch from the reference lakes that contain levels of PFOS below what is recommended for daily consumption by the Swedish EPA.
For all individuals of perch that have been analysed, the sex and age is always determined but these biological parameters have not shown to have any influence on the bioaccumulation potential and the concentrations in the fish. Bioconcentration factors (BCF) from water to the fish from the literature and when the BCF are applied to the RE-PATH data from all the lakes included in the sampling program, the predicted concentration in fish agrees well with the actual concentration in the perch. This can be a useful tool in monitoring. Due to consumption and human exposure, it is the muscle in the fish that has been analysed. But for several individuals of female perch, also liver, gills, blood and gonads were analysed. The liver and the blood contain the highest levels of PFOS, approximately 15 times more than the muscle where only a few per cent of the total amount of PFOS is accumulated.
Sediment was sampled during the first year of RE-PATH when the concentration of PFOS was higher in samples from Lake Halmsjön compared to the reference lake, but the same levels as in Lake Halmsjön were also found in different sediment samples from Mälaren. Sediment was further investigated in order to study if it can act as possible source of PFOS to the water. Experiments on sediment from Lake Halmsjön showed that the contribution from the sediment to the water concentration can be neglected. Further, sediment seems not to be acting as a sink for PFOS.
Since RE-PATH started several ecotoxicological studies have been performed. Effect concentrations in perch, frog and zebrafish have been determined for PFOS, AFFF but also for Moussol FF, the fire fighting foam that is used today with no fluorine containing compounds. Perch roam has been collected from Lake Västra Ingsjön and Lake Halmsjön and the hatching frequency and the deformation frequency were studied. The frequency for hatching was high for both lakes and the deformation of the fries was low. Bioaccumulation and excretion of PFOS have been studied in zebrafish and crayfish. The zebrafish was exposed for ten weeks and a steady state was never reached during the time period. However, it was shown that the males were able to bioaccumulate the double amount of PFOS compared to the females, but the concentrations did not decrease in neither of the sex during a two week excretion period. Crayfish from Lake Halmsjön did excrete PFOS and after four weeks the concentration had decreased to approximately halft of the original concentration. However, after 16 week, the decrease was significant and the crayfish contained 10% of their original PFOS-concentration.
During the four years of the RE-PATH project has been going on, the concentrations in fish and water has not changed. Questions that have been raised are for how long will this leakage go on and are there remediation possibilities to reduce the leakage? At the moment there are no ways to clean soil and water from PFOS that has shown to be efficient and a mass balance model have been conducted to calculate how long time is needed before the concentrations will reach background levels. The model simulates that it will take approximately 60 years for the area to reach background levels of PFOS.