Peripubertal blood lead levels and semen quality in a prospective cohort study of Russian men

Abstract

To assess associations between peripubertal blood lead levels and semen parameters. A prospective cohort study conducted in Chapaevsk, Russia From 2003 to 2005, 499 boys were enrolled at age 8-9 years and their growth and development were assessed annually for ten years. Blood lead levels (BLLs) were measured at enrollment using atomic absorption spectrometry. At ages 18-19 years, 137 young men provided up to two semen samples collected one week apart (264 samples) which were analyzed for volume, sperm concentration and motility according to NAFA and ESHRE-SIGA methods. Total sperm count and total motile sperm count were calculated. Linear mixed models were used to examine the relation between BLLs (<5 and ≥5 mcg/dL, CDC reference for childhood lead exposure) and semen parameters, with random intercepts to account for multiple semen samples per participant. Men had a median total sperm count, total motile sperm count and motility of 126 million, 80 million and 64%, respectively. Higher peripubertal BLLs were associated with lower total sperm count and total motile sperm count. Men who had peripubertal BLLs ≥5 mcg/dl had 30% lower total sperm count (p-value=0.09) and 31% lower total motile sperm count (p-value=0.11) compared with men who had BLLs < 5mcg/dL. BLLs were not associated with motility. This is the first study to examine the association between peripubertal BLLs and semen quality in young adulthood. We observed suggestive evidence that peripubertal BLLs above the CDC reference level could be associated with poorer semen quality, indicating that the peripubertal period may be a sensitive window of exposure. Lead exposure continues to be a major public health problem in the United States and Russia, thus these results add to our understanding of reproductive health risks from childhood lead exposure.