Survey of methylmercury in fish and seafood from the southwestern German market

Mercury is an environmental contaminant and may occur as methylmercury in marine organisms. Methylmercury is considered as having higher toxicity than the inorganic form; therefore, it is important to differentiate the mercury species in order to evaluate the potential risk for seafood consumers. In the largest study of the German market to date, 536 marine foods from the state of Baden-Wurttemberg (southwestern Germany) were analyzed using gas chromatography with atomic emission detection. Methylmercury was found at levels ranging from non-detectable (below 6 μg/kg) up to 567 μg/kg. The average, median, 90th, 95th, and 99th percentile contents were 38, 22, 78, 117, and 316 μg/kg, respectively. The average methylmercury proportion of total mercury was 70%. Based on a daily total fish and seafood consumption of 30 g according to the German National Nutrition Survey II, the methylmercury exposure was estimated to range between 5 μg/week (median) and 67 μg/week (99th percentile), which was below the provisional tolerable weekly intake (PTWI) established by the Joint FAO/WHO Expert Committee on Food Additives. The risk of methylmercury for the German fish consumer was judged to be rather low, being restricted to the unlikely worst-case scenario of daily consumption of highly contaminated fish, which could exceed the PTWI. In conclusion, the previous opinions that the benefits of the moderate fish consumption appear to outweigh the risks associated with methylmercury exposure were confirmed by our survey.