Risk Assessment of PFOS-Contaminated Fish a Swedish Example

In Sweden extensive use of fire-fighting foams containing perfluorooctane sulfonate (PFOS) and related substances has resulted in PFOS contamination of freshwater fish (e.g. perch, pike). PFOS intake from contaminated fish in relation to the EU tolerable daily intake (150 ng PFOS/kg/day, TDI), was modelled as a scientific basis for risk management decisions about fish consumption. PFOS levels in freshwater fish of up to 1000 ng PFOS/g have been reported. In scenario calculations, PFOS levels in other foods were assumed to be at background levels. Food consumption data came from nation-wide food consumption surveys Riksmaten 2003 (children) and Riksmaten 2010-11 (adults). Assuming adult consumption of freshwater fish with an average background PFOS level (4 ng PFOS/g fresh weight), median PFOS intake was estimated to 1.1 ng/kg body weight/day (95th percentile: 3.2 ng/kg/d). Consumption of fish with 150 ng PFOS/g gave a median intake of 16 ng/kg/d (68 ng/kg/d) among adults. Using the same scenarios, median intake among 4 year old children increased from 0.53 ng/kg/d (1.0 ng/kg/d) to 46 ng/kg/d (130 ng/kg/d). At 1000 ng PFOS/g, median intake among adults and 4 year old children was estimated to 100 ng/kg/d (450 ng/kg/d) and 300 ng/kg/d (870 ng/kg/d), respectively. The amount of contaminated fish that could be consumed without exceeding the TDI was estimated (threshold consumption, TC). Relationships between fish consumption and PFOS intake was described using a Hill model. For fish containing 200 ng PFOS/g, geometric mean TC for adults was 58 g/d (95% confidence interval: 55-60 g/d). For 4 year old children TC was estimated to 14 (13-14) g/d. At 1000 ng/g, adults had a TC of 11 (11-11) g fish/d and 4 year old children 2.7 (2.7-2.8) g/d. Regular consumption of contaminated fish greatly influences total PFOS intake from food. At very high PFOS levels in fish, one portion of contaminated fish (100 g) per month is enough for young children to exceed the TDI.