The Mercury Concentration in Breast Milk Resulting from Amalgam Fillings and Dietary Habits

Health risks from amalgam fillings are a subject of controversy. In Germany it is not advised to use amalgam fillings during breast feeding. Objectives of this study were to examine the concentration of mercury in human breast milk and the confounders which may modify the mercury levels. Women who gave birth between August 1995 and May 1996 in a district hospital were asked to participate in the study. The examination included a standardized anamnesis and an inspection of the teeth by an dentist. Blood and urine samples of 147 women and breast milk samples of 118 women were collected in the first week after birth. After 2 months of breast feeding a second breast milk sample was collected from 85 of women. Mercury was measured by cold-vapor atomic absorption spectrometry. The concentration of mercury in the breast milk collected immediately after birth showed a significant association with the number of amalgam fillings as well as with the frequency of meals. Urine mercury concentrations correlated with the number of amalgam fillings and amalgam surfaces. In the breast milk after 2 months of lactation, the concentrations were lower (mean: <0.25 μg/L; range <0.25–11.7 μg/L) compared with the first sample (mean: 0.90 μg/L; range <0.25–20.3 μg/L) and were positively associated with the fish consumption but no longer with the number of the amalgam fillings. Accordingly, the additional exposure to mercury of breast-fed babies from maternal amalgam fillings is of minor importance compared to maternal fish consumption.