Total and Inorganic Mercury in Breast Milk and Blood in Relation to Fish Consumption and Amalgam Fillings in Lactating Women

Abstract

Total mercury concentrations (mean +/- standard deviation) in breast milk, blood, and hair samples collected 6 wk after delivery from 30 women who lived in the north of Sweden were 0.6 +/- 0.4 ng/g (3.0 +/- 2.0 nmol/kg), 2.3 +/- 1.0 ng/g (11.5 +/- 5.0 nmol/kg), and 0.28 +/- 0.16 microg/g (1.40 +/- 0.80 micromol/kg), respectively. In milk, an average of 51% of total mercury was in the form of inorganic mercury, whereas in blood an average of only 26% was present in the inorganic form. Total and inorganic mercury levels in blood (r = .55, p = .003; and r = .46, p = .01 6; respectively) and milk (r = .47, p = .01; and r = .45, p = .018; respectively) were correlated with the number of amalgam fillings. The concentrations of total mercury and organic mercury (calculated by subtraction of inorganic mercury from total mercury) in blood (r = .59, p = .0006, and r = .56, p = .001; respectively) and total mercury in hair (r = .52, p = .006) were correlated with the estimated recent exposure to methylmercury via intake of fish. There was no significant between the milk levels of mercury in any chemical form and the estimated methylmercury intake. A significant correlation was found between levels of total mercury in blood and in milk (r = .66, p = .0001), with milk levels being an average of 27% of the blood levels. There was an association between inorganic mercury in blood and milk (r = .96, p < .0001); the average level of inorganic mercury in milk was 55% of the level of inorganic mercury in blood. No significant correlations were found between the levels of any form of mercury in milk and the levels of organic mercury in blood. The results indicated that there was an efficient transfer of inorganic mercury from blood to milk and that, in this population, mercury from amalgam fillings was the main source of mercury in milk. Exposure of the infant to mercury from breast milk was calculated to range up to 0.3 microg/kg x d, of which approximately one-half was inorganic mercury. This exposure, however, corresponds to approximately one-half the tolerable daily intake for adults recommended by the World Health Organization. We concluded that efforts should be made to decrease mercury burden in fertile women.

Methyl Mercury and Inorganic Mercury in Swedish Pregnant Women and in Cord Blood: Influence of Fish Consumption

“…Dental amalgam fillings have previously been shown to influence I-Hg in maternal blood (Oskarsson et al 1996;Vahter et al 2000), placenta (Ask et al 2002), fetal blood (Vahter et al 2000), and fetal tissue (Drasch et al 1994;Lutz et al 1996). I-Hg in cord blood (median = 0.15 µg/L) was even lower than in our previous study of Swedish pregnant women (median = 0.34 µg/L) (Vahter et al 2000).…”

Biological Monitoring of Exposure: Trends and Key Developments

“…The obtained benchmark dose (BMDL 5%) of approximately 10 µg/g maternal hair was similar to that calculated for other neurological variables 48) in the Faroese children and in the New Zealand population 49) . The present background level of Hg-H, associated with no or low fish consumption or a low fish methylmercury concentration, amounts to from 0.25 µg/g to 0.8 µg/g [50][51][52]) . Much higher Hg-H levels result from the consumption of large amounts of fish or sea mammals.…”

Estimation of Target Hazard Quotients and Potential Health Risks for Metals by Consumption of Seafood in Taiwan

“…People consuming large amounts of contaminated seafood may have elevated concentration of heavy metals in their tissues compared to the general population (Asplund et al 1994;Dewailly et al 1994). A correlation between blood mercury levels and methylmercury exposure via fish consumption has been shown in several different studies (Grandjean et al 1992;Svensson et al 1992;Oskarsson et al 1996). For example, in the Faroe Islands, the community consumes much seafood, and the hair mercury concentration in infants increases with the duration of the nursing period (Grandjean et al 1994).…”