Methylmercury and Inorganic Mercury in Serum—Correlation to Fish Consumption and Dental Amalgam in a Cohort of Women Born in 1922

Abstract

Methylmercury in serum (S-MeHg) was assessed from serum concentrations of total (S-TotHg) and inorganic mercury (S-InoHg), determined by cold vapor–atomic absorption spectrometry. The samples were collected from 135 women on two occasions, in 1968–1969 and 1980–1981. In a subgroup of 29 women, an association was found between S-MeHg and the amount of fish consumed in 1968–1969 (r=0.38,P=0.04). The association was stronger (r=0.50;P=0.006) when the individuals' mean S-MeHg from 1968–1969 and 1980–1981 were plottedvsfish consumption 1968–1969. In the group, as a whole, there was an association between S-InoHg and number of dental amalgam surfaces, in both 1968–1969 (r=0.48,P=0.0001) and 1980–1981 (r=0.57,P<0.0001). The S-InoHg increased by approximately 0.1 nmol/L per amalgam tooth surface, corresponding to an uptake of approximately 0.2 μg/day per amalgam surface, but with considerable interindividual differences. The levels were lower in 1980–1981 than in 1968–1969 for both MeHg and InoHg. The medians and ranges (nmol/L) were for MeHg 1968–1969: 3.6 (0.3–11.9); MeHg 1980–1981, 2.0 (−0.4–8.7); InoHg 1968–1969, 3.3 (0.7–11.8); InoHg 1980–1981, 1.7 (0.1–11.8); TotHg 1968–1969, 7.2 (1.9–18.8); and TotHg 1980–1981, 3.9 (1.0–14.2). The decrease in S-MeHg is probably due to a decreased consumption of MeHgviacontaminated fish. The decrease in S-InoHg may reflect a decrease in environmental exposure, but the possibility of contamination of the 1968–1969 samples at sampling and/or storage cannot be excluded.