Predictors of toxic metal exposures among US women of reproductive age

Background Arsenic, cadmium, lead, and mercury are ubiquitous toxicants that may be especially harmful to unborn children. We therefore sought to identify temporal trends and predictors of toxic metal biomarkers among US women of reproductive age, including those who were pregnant and/or breastfeeding. Methods Interviews and examinations were performed among a representative sample of women, aged 20-44 years, as part of the 2003-2014 National Health and Nutrition Examination Surveys. A range of sociodemographic, lifestyle, and dietary factors were evaluated as predictors of urinary inorganic arsenic, urinary cadmium, blood mercury, and blood lead concentrations. Results Levels of all four toxic metal biomarkers declined during the study period. Older age, racial/ethnic minorities, and a birthplace outside of the US were independently associated with higher toxic metal concentrations. Associations were similar for women who were pregnant or breastfeeding and those who were not. Conclusion US women of reproductive age were exposed to lower levels of toxic metals in 2013-2014 compared to 2003-2004. However, because the long-term health effects of early life exposures are unclear, public health efforts to address toxic metals should pay particular attention to older, nonwhite, and foreign-born women if they are pregnant or planning to become pregnant.