Abstract
This study examined the relationship between infant birth weight and exposure during pregnancy to three non-essential trace metals, cadmium, lead, and mercury, and one essential trace metal, manganese. Small-scale gold mining has contaminated freshwater fish with mercury, a primary food resource, in interior regions of Suriname, South America. Whole blood samples from pregnant women collected in early pregnancy (late first trimester or early second trimester) were used to determine trace metal concentrations. Inductively-coupled plasma mass spectrometry was used to measure trace metal concentrations. Bayesian kernel machine regression was used to evaluate the association of trace metal exposures on infant birth weight and possible interactions among trace elements. Lead was negatively associated with birth weight. Mercury appeared to affect birth weight in a non-linear fashion. Low birth weight was observed at low concentrations of blood mercury. Birth weight increased with increasing concentrations of mercury up to the higher concentrations of mercury where birth weight appeared to trend downward. Lead and mercury interacted such that high concentrations of lead and low concentrations of mercury were associated with low birth weight. Cadmium and manganese were not associated with birth weight in this study. Lead has been observed in previous studies to negatively influence birth weight as this study found. The association of mercury with birth weight in this study might reflect diet quality. With fish being a principal dietary source of mercury in this population and knowing that consumption of nutrient packed fish is beneficial for children's physical and neurological development, low concentrations of mercury may reflect the absence or low level of fish consumption in the maternal diet. The mechanistic and clinical health implications of these associations with birth weight require further investigation.