Environmental exposure to metals and male reproductive hormones: circulating testosterone is inversely associated with blood molybdenum.

OBJECTIVE

To explore associations between exposure to metals and male reproductive hormone levels.

DESIGN

Cross-sectional epidemiology study with adjustment for potential confounders.

SETTING

University Medical Center.

PATIENT(S): Men recruited through two infertility clinics in Michigan.

INTERVENTION(S): Metal concentrations and reproductive hormone levels were measured in blood samples collected from 219 men.

MAIN OUTCOME MEASURE(S): Serum FSH, LH, inhibin B, T, and sex hormone-binding globulin levels.

RESULT(S): Cadmium, copper, and lead were all significantly or suggestively positively associated with T when modeled individually, findings that are consistent with limited previous human and animal studies. Conversely, molybdenum was associated with reduced T. A significant inverse trend between molybdenum and T remained when additionally considering other metals in the model, and a positive association between T and zinc was also found. Finally, in exploratory analysis there was evidence for an interaction between molybdenum and zinc, whereby high molybdenum was associated with a 37% reduction in T (relative to the population median level) among men with low zinc.

CONCLUSION(S): Although reductions in T and reproductive toxicity after molybdenum exposure have been previously demonstrated in animal studies, more research is needed to determine whether molybdenum poses a risk to human reproductive health.