engleski

Suitability of biomarkers of low-to-medium mercury exposure in pregnant women,

Based on the results obtained in a preliminary and a large-scale study as part of the PHIME project (EU 6th framework programme), suitability of selected biomarkers of low-to-moderate mercury (Hg) exposure was evaluated. In the preliminary study, MeHg (methyl mercury) and THg (total mercury) were determined in maternal blood, umbilical cord blood, placenta, meconium, maternal scalp and pubic hair collected from 28 mother-child pairs. In the following longitudinal cohort study, THg and MeHg were determined in maternal scalp hair, maternal blood, umbilical cord blood and breast milk from 618 mother-child pairs from Mediterranean region. Both studies showed variable proportion of Hg as MeHg in maternal and cord blood (12 to 100 %) and scalp hair (10 to 100 %), and highly variable inter-individual hair-to-blood MeHg ratio (67 to 760). Nevertheless, the median values for proportion of Hg as MeHg in cord blood and hair were 97 and 99 %, respectively. Maternal scalp hair MeHg was associated more strongly with blood than pubic hair MeHg (r=0.621, p=0.008 and r=0.468, p=0.058, respectively). Th e significance of placenta as an indicator of MeHg or inorganic Hg exposure is questionable, while meconium was found to indicate MeHg exposure to a certain extent, although the negligible proportion of Hg present as MeHg in meconium indicated possible demethylation of MeHg in the foetus. In contrast to blood and hair, very weak association between THg and MeHg was observed in breast milk (r=0.138, p=0.025), while the proportion of Hg as MeHg was negatively associated with THg (r=-0.305, p<0.001). In all conducted studies, Hg in blood and hair was positively and significantly associated with the frequency of fish consumption, while THg in urine was positively and significantly associated with the number of dental amalgam fillings. Hg in breast milk was more strongly and significantly associated with the number of amalgam fillings than with the frequency of fish consumption. Although Hg in blood is the most suitable biomarker of inorganic Hg or MeHg exposure, when speciation analysis is performed, THg in hair was found to be sufficient as an approximate indicator of exposure to MeHg resulting from fish consumption and THg in urine as a good indicator of exposure to inorganic Hg from dental amalgam fillings. Breast milk THg was observed to indicate mainly inorganic Hg exposure

biomarkers of mercury exposure; pregnant women

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