Abstract

Aims: To investigate time to pregnancy (TTP) in male lead workers in order to determine the dose-response relation between blood lead and decreased fecundity.

Methods: A total of 163 currently employed married male lead battery workers were classified into five categories of exposure based on questionnaire information and annual individual blood lead measurement. Information pertaining to the TTP was collected using personal interviews with 133 men and their spouses, with 280 valid pregnancies. The fecundability ratios (FRs) were calculated with the Cox discrete proportional hazard regression technique to evaluate the effects of lead exposure.

Results: After other factors associated with TTP were controlled for, there was a dose-response relation between blood lead level and TTP. The measured FRs were 0.90 (95% CI 0.61 to 1.34), 0.72 (0.46 to 1.11), 0.52 (0.35 to 0.77), and 0.40 (0.27 to 0.59) for concurrent blood lead levels of <20, 20–29, 30–39, and ⩾40 μg/dl, respectively. Paired self comparison was also performed for 41 couples that had pregnancies prior to lead exposure and pregnancies with male occupational lead exposure. The TTP was prolonged for 0.15 cycles by a 1 μg/dl increase in blood lead.

Conclusions: These results corroborate the hypothesis that a raised blood lead level affects fecundity. A blood lead level of less than 40 μg/dl may still significantly prolong TTP.