Ambient manganese exposure is negatively associated with human sperm motility and concentration.

BACKGROUND

Occupational and experimental animal studies indicate that exposure to high levels of manganese impairs male fertility, but the effects of ambient manganese in humans are not known.

METHODS

We measured blood levels of manganese and selenium in 200 infertility clinic clients in a cross-sectional study. Correlations between metals and semen variables were determined, adjusting for other risk factors. Outcomes were low motility (<50% motile), low concentration (<20 million/mL), or low morphology (<4% normal). We also investigated dose-response relationships between quartiles of manganese exposure and sperm parameters.

RESULTS

High manganese level was associated with increased risk of low sperm motility (odds ratio = 5.4; 95% confidence interval = 1.6-17.6) and low sperm concentration (2.4; 1.2-4.9). We saw a U-shaped dose-response pattern between quartiles of manganese exposure and all 3 sperm parameters.

CONCLUSION

Ambient exposure to manganese levels is associated with a reduction in sperm motility and concentration. No adverse effects were seen for high selenium.