Determinants of the Blood Lead Level of U.S. Women of Reproductive Age

Abstract

Lead toxicity continues to be a major public health concern in the United States and elsewhere. Levels of lead in umbilical cord blood and breast milk correlate closely with those in maternal blood. It appears that blood and tissue lead levels in women of reproductive age determine the body burden of lead in their children. The investigators sought determinants of the blood lead level (BLL) in 4394 women 20 to 49 years of age who participated in the most recently completed National Health and Nutritional Survey (NHANES III). Complete data were obtained from 3716 women. The geometric mean BLL was 1.78 μg/dL. Lead levels correlated inversely with educational level, hematocrit, thiamine intake, and serum folate level. Positive associations were found between BLL and ethnicity (blacks and Hispanics had relatively high levels), living in an urban area, older age, alcohol consumption, and cigarette smoking. In addition, the BLL correlated positively with serum protoporphyrin levels and with the intake of pyridoxine, iron, and folate. On logistic regression analysis, comparing subjects with a BLL above 4.0 μg/dL (upper decile) with those in the lowest decile (less than 0.7 μg/dL) showed high odds ratios for 4 significant variables: alcohol consumption, cigarette smoking, thiamine intake, and serum ascorbic acid concentration. This analysis controlled for many variables, including breast feeding, total fat intake, serum and red blood cell folate levels, and hematocrit. Women who drank alcohol were more than 5 times likelier than abstainers to be in the highest decile for BLL, and the odds ratio for smokers was 4.5. Women with a thiamine intake greater than 1 mg were 7.5 times less likely than those with a lower intake to be in the highest decile. A high serum ascorbic acid level correlated with a 2.5-fold lower chance of having a BLL in the highest decile. Women with the lowest serum folate levels had significantly higher BLLs than those with values in the upper decile. The investigators conclude that lowering the mother's body burden of lead can reduce blood lead toxicity in children. It may prove feasible to use vitamins such as thiamine and ascorbic acid to prevent (or treat) lead toxicity.