Lead exposure is associated with a delay in the onset of puberty in South African adolescent females: Findings from the Birth to Twenty cohort

摘要

Introduction: One of the suggested, yet under-researched, causes of pubertal delay is lead exposure. In SouthrnAfrica blood lead levels are generally higher than in resource-rich countries. Thus the effects of lead exposurernon pubertal development may be significant.rnObjective: The objective of this study is to determine the association between lead exposure and pubertalrndevelopment in adolescent females in the Birth to Twenty cohort (Bt2O).rnMethods: Bt20 is a Johannesburg based birth cohort study that commenced in 1990 and includes 1682 girls.rnAt 13 years of age venous blood samples were collected from 725 adolescent female participants for leadrncontent analyses; of these, 712 had menarche data. Pubertal measurement was based on age of menarchernand self-reported Tanner staging for pubic hair (n = 684) and breast development (n = 682).rnResults: The mean blood lead level for the sample was 4.9 μg/dl. Fifty percent had blood lead levels <5.0 μg/dl,rn49% were ≥5.0 μg/dl and 1% was >10.0 μg/dl. The average age of menarche was 12.7 years. At 13 years, 4%rnand 7% had reached Tanner stage 5 for pubic hair and breast development, respectively. Analyses showedrnthat higher blood lead levels were associated with significant delays in the onset of puberty (p<0.001).rnConclusion: The study found that higher blood lead levels were associated with a delay in the onset ofrnpuberty, after adjustment for confounders. Lead exposure in resource-poor countries is generally higherrncompared to resource-rich countries and thus the effects of high blood levels have personal and public healthrnsignificance.