Background Cross-sectional studies have suggested that occupational lead exposure may adversely affect sperm quality. Methods Sperm quality changes were prospectively assessed in 19 men employed at a car battery plant where efforts were made to decrease the exposure level. The participants delivered monthly samples of semen and venous blood during their employment at the factory. The factory then closed, and additional samples were obtained from 16 of the men. Results Average blood-lead concentrations decreased from 2.03 >mol/l to 0.96 >mol/l during the observation period. Concomitantly, significant improvements were seen in the proportion of motile cells both at sample delivery and after 24 hr, and in penetration. However, the sperm cell concentration and the proportion of morphological abnormalities did not change. Conclusions These results support the notion that occupational lead exposure at currently acceptable levels has a small adverse effect on sperm quality, especially sperm motility, and that this effect is at least partially reversible.

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