Exposure to methylmercury in non-fish-eating people in Sweden

The extensive use of fish meal as a source of protein for poultry and swine may lead to additional exposure to methylmercury (MeHg). We determined the concentration of MeHg and inorganic mercury (I-Hg) in blood and total mercury (T-Hg) in hair in 27 persons (9 men and 18 women, 20-58 years of age) who stated that they had consumed no fish for a period of 2 years or more. The participants answered a food frequency questionnaire and reported their number of dental amalgam fillings. The MeHg concentrations in blood (median, 0.10 microg/L; range, 0.0-1.0 microg/L) were very low and did not constitute a concern for health effects. We also analyzed selenium (Se) in serum. The median concentration was 76 microg/L (range, 53-103 microg/L), which is in agreement with previous studies of the Swedish general population, indicating that the Se status of non-fish-eating individuals is not substantially lower than that of people who include fish in their diet. We found a significant association (P=0.002) between the number of dental amalgam fillings and the I-Hg concentration in blood (median, 0.09 microg/L; range, 0.03-0.57 microg/L). The T-Hg in hair (median, 0.06 mg/kg; range, 0.04-0.32 mg/kg) was significantly associated (R2=0.89; P<0.001) with the MeHg in blood, but not with the I-Hg in blood. Therefore, the T-Hg in hair seems to reflect MeHg exposure and not I-Hg exposure even in persons with no intake of fish.