Infants and mothers levels of mercury in breast milk, urine and hair, data from an artisanal and small-scale gold mining area in Kadoma/Zimbabwe

In Kadoma (Zimbabwe) gold is extracted from ore based on a simple technology using mercury. Women are exposed whilst living in an exposed area, or even more working directly with mercury. Breast fed infants are exposed via mercury contaminated milk and the general environmental mercury exposure. The aim of the study was to measure infants and mothers levels of mercury in urine and hair, as well as in breast milk. In 2006, an environmental epidemiological field study with 120 mother - child pairs was conducted. A non exposed control group (n = 42) was compared with a medium exposed group (n = 51) and a high exposed group (occupational exposure, n = 27). Urine and hair samples from mother and infants plus breast milk samples were analyzed for total mercury. 120 breast milk samples were analyzed, median (maximum) concentrations [mu g Hg/1] were (i) control group < 0.50 (1.55), (ii) medium exposed group 1.10 (10.48), (iii) high exposed group 1.20 (24.80) (p < 0,001). Urine and hair results were distributed similarly for infants and mothers, with higher levels according to the exposure subgroup. All specimen results correlated very well with another, indicating there is a pathway between breast milk and infant's level of mercury. The daily uptake of mercury via breast milk was calculated. The reference dose of 0.3 degrees [mu g Hg/kg BW/d] was used to compare the burden of the infants. No infant from the control group, but 17.6% of the medium and 18.5% of the high exposed group were above the reference dose. Mercury in breast milk is generally higher in artisanal and small scale gold mining areas. Breast fed infants were burdened with toxic mercury via breast milk and via the general environment, both are important public health issues.