To examine whether in utero exposure to mercury (Hg), cadmium (Cd), lead (Pb) and arsenic (As) is associated with an elevated neural tube defects (NTDs) risk, placental concentrations of total Hg, Cd, Pb and As were measured with an inductively coupled plasma mass spectrometer (ICP-MS) in 36 anencephaly and 44 spina bifida cases as well as in 50 healthy controls. The median Hg concentration in the NTD cases (2.25 ng/g) was higher than that of the controls (1.16 ng/g). The odds ratio (OR) for an Hg concentration above the median was 8.80 (95% CI 3.80-20.36) for the NTD cases. NTD risks increased for the second and third high levels of the concentrations, with ORs of 2.70 (95% CI 1.13-6.43) and 18.20 (95% CI 5.45-60.73), respectively. Therefore, higher placental levels of Hg are associated with an elevated risk of NTDs.
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