Fish as a source of exposure to mercury and selenium

Abstract

In a total of 395 subjects with varying fish consumption habits, mercury levels in whole blood (BHg), and selenium levels in plasma (PSe) were studied. Also, in subcohorts, mercury levels in blood cells (EryHg; n = 79), plasma (PHg; n = 158) and urine (UHg; n = 125) were analysed. There were statistically significant associations between fish intake on the one hand, and BHg, EryHg and PHg, on the other, but not so with UHg. In subjects who never had fish, the average BHg was 1.8 ng/g, in subjects who had at least two fish meals each week, 6.7 ng/g. EryHg, and to a less extent PHg, were associated with levels of marine n-3 polyunsaturated fatty acids (PUFA) in serum phosphatidylcholine. PHg and UHg were associated with numbers of teeth with amalgam fillings. PSe also correlated with fish intake. In subjects who never had fish, PSe averaged 80 μg/l, in subjects who had at least two fish meals per week, 91 μg/l. There was an association between PUFA and PSe. Further, there were statistically significant associations between PSe on the one hand, and BHg, EryHg and PHg on the other. The data clearly demonstrate the importance of fish for the exposure to methylmercury and selenium in the Swedish diet, and the impact of amalgam as a source of exposure to inorganic mercury.