Blood lead levels and sexual maturation in U.S. girls: the Third National Health and Nutrition Examination Survey, 1988-1994

Using data from the Third National Health and Nutrition Examination Survey, we assessed measures of puberty in U.S. girls in relation to blood lead levels to determine whether sexual maturation may be affected by current environmental lead exposure. The study sample included 1,706 girls 8-16 years old with pubic hair and breast development information; 1,235 girls 10-16 years old supplied information on menarche. Blood lead concentrations (range = 0.7-21.7 micro g/dL) were categorized into three levels: 0.7-2.0, 2.1-4.9, and 5.0-21.7 micro g/dL. Sexual maturation markers included self-reported attainment of menarche and physician determined Tanner stage 2 pubic hair and breast development. Girls who had not reached menarche or stage 2 pubic hair had higher blood lead levels than did girls who had. For example, among girls in the three levels of blood lead described above, the unweighted percentages of 10-year-olds who had attained Tanner stage 2 pubic hair were 60.0, 51.2, and 44.4%, respectively, and for girls 12 years old who reported reaching menarche, the values were 68.0, 44.3, and 38.5%, respectively. The negative relation of blood lead levels with attainment of menarche or stage 2 pubic hair remained significant in logistic regression even after adjustment for race/ethnicity, age, family size, residence in metropolitan area, poverty income ratio, and body mass index. In conclusion, higher blood lead levels were significantly associated with delayed attainment of menarche and pubic hair among U.S. girls, but not with breast development.