Abstract
BACKGROUND: Prenatal exposure to methylmercury is associated with adverse neurologic development in children. We examined total blood mercury concentrations and predictors of higher blood mercury concentrations in pregnant and nonpregnant women. METHODS: We analyzed data from 1183 pregnant and 5587 nonpregnant women aged 16-49 years from the 1999-2006 National Health and Nutrition Examination Survey (NHANES). We estimated geometric mean blood mercury concentrations and characteristics associated with higher mercury concentrations (≥3.5 μg/L) in crude and adjusted linear and logistic regression models. RESULTS: After adjusting for age and race/ethnicity, geometric mean blood mercury concentrations were clinically similar but significantly lower for pregnant (0.81 μg/L; 95% confidence interval [CI], 0.71-0.91) and nonpregnant women of childbearing age (0.93 μg/L; 95% CI, 0.87-0.99); 94% of pregnant and 89% of nonpregnant women had blood mercury concentrations below 3.5 μg/L. The most significant predictor of higher blood mercury concentrations for both pregnant and nonpregnant women was any seafood consumption vs no consumption in the last 30 days (odds ratio, 18.7; 95% CI, 4.9-71.1; odds ratio, 15.5; 95% CI, 7.5-32.1, respectively). Other characteristics associated with ≥3.5 μg/L blood mercury concentrations were older age (≥35 years), higher education (greater than high school), and higher family income to poverty ratio (3.501+) for both pregnant and nonpregnant women. CONCLUSION: Pregnancy status was not strongly associated with blood mercury concentrations in women of childbearing age and blood mercury concentrations above the 3.5 μg/L cut were uncommon.