Mercury levels in the hair of pregnant women in a polluted area in Sweden.

Total mercury concentration in hair, sampled at delivery, was determined in women living in an area polluted with atmospheric emissions of mercury from a metal smelter, (n = 122) and in a control area (n = 75). Information on fish consumption was obtained at the 10th week of pregnancy. The average mercury concentration in hair was 0.27 mg/kg (range 0.07-0.96 mg/kg), which is somewhat lower than previously reported for pregnant women in Sweden and very low compared with levels in fish-eating populations in other parts of the world. Women living in the polluted area had significantly lower mercury levels in hair than women in the control area when comparing groups with quantitatively similar consumption of freshwater fish. Possibly, the population in the smelter area does not catch fish in the neighbourhood and/or the fish in the control area has elevated mercury levels. Consumption of freshwater fish > or = once a week resulted in approximately twice as high hair mercury levels as in those who did not eat freshwater fish at all. Also consumption of saltwater fish > or = once a week resulted in significantly higher hair mercury levels than in those consuming saltwater fish < once a month. Hair levels from the 10th week of pregnancy were similar to the levels at delivery in women with high (> or = once a week) consumption of freshwater fish but decreased during this period in women who did not eat freshwater fish at all, which could be explained by decreased exposure during pregnancy and measurement in recently formed hair.