Blood Lead Levels in US Women of Childbearing Age, 1976-2016

BACKGROUND: Lead can adversely affect maternal and child health across a wide range of exposures; developing fetuses and breastfeeding infants may be particularly vulnerable. We describe the distribution of blood lead levels (BLLs) in U.S. women of childbearing age and associations with sociodemographic, reproductive, smoking, and housing characteristics over a 40-y period. METHODS: Data from the National Health and Nutrition Examination Survey (NHANES) II, NHANES III Phase I and Phase II, and 1999-2016 continuous NHANES were used to describe the distribution of BLLs (given in micrograms per deciliter; 1 mu g/dL = 0.0483 mu mol/L) in U.S. women 15-49 years of age between 1976 and 2016. For all women with valid BLLs = 22,408), geometric mean (GM) BLLs and estimated prevalence of BLLs >= 5 mu g/dL were calculated overall and by selected demographic characteristics. For NHANES II, estimated prevalence of BLLs >= 10 and >= 20 mu g/dL were also calculated. RESULTS: The most recent GM BLLs (2007-2010 and 2011-2016, respectively) were 0.81 mu g/dL [95% confidence interval (CI): 0.79, 0.84] and 0.61 mu g/dL (95% CI: 0.59, 0.64). In comparison, GM BLLs in earlier periods (1976-1980, 1988-1991, and 1991-1994) were 10.37 mu g/dL (95% CI: 9.95, 10.79), 1.85 mu g/dL (95% CI: 1.75, 1.94), and 1.53 mu g/dL (95% CI: 1.45, 1.60), respectively. In 2011-2016, 0.7% of women of childbearing age had BLLs >= 5 mu g/dL, and higher BLLs were associated with older age, other race/ethnicity, birthplace outside the United States, four or more live births, exposure to secondhand tobacco smoke, and ever pregnant or not currently pregnant. DISCUSSION: Lead exposure in U.S. women of childbearing age is generally low and has substantially decreased over this 40-y period. However, based on these estimates, there are still at least 500,000 U.S. women being exposed to lead at levels that may harm developing fetuses or breastfeeding infants. Identifying high-risk women who are or intend to become pregnant remains an important public health issue.