Mercury concentrations in urine, scalp hair, and saliva in children from Germany
Mercury levels measured in urine, hair, and saliva of 245 German children (8–10 years old) are reported. Mercury concentrations in urine ranged between <0.1 and 5.3 g/l [geometric mean (GM) 0.26 g/l or 0.25 g/g creatinine; median for both, 0.22 in g/l and g/g, respectively]. Using multiple linear regression analysis, two predictors have been found accounting for 25.3% of the variance of mercury levels in urine: the number of teeth with amalgam fillings (23.2%) and the number of defective amalgam fillings (2.1%). The mercury content in hair ranged from <0.06 to 1.7 g/g (GM 0.18 g/g; median 0.18 g/g). The frequency of fish consumption, the smoking habits of the parents, and the age of the children accounted for 20.4% of the variance of mercury levels in hair. The correlation between the hair mercury content and urine mercury concentration was low (r=0.297). Mercury levels in saliva ranged between <0.32 and 4.5 g/l (median 0.16 g/l). The mercury concentration in saliva was below the limit of quantification of 0.32 g/l in more than 70% of the samples. Mercury analysis in urine is suitable to estimate mercury exposure due to amalgam fillings, whereas hair mercury better reflects mercury intake by fish consumption. Up to now, saliva does not seem to be a suitable tool to monitor the mercury burden, at least not at low exposure levels.