Fertility of Danish battery workers exposed to lead

Background. inorganic lead may impair male fecundity through its action on the germinal epithelium, the endocrine system or both, but information on possible impact on fertility in exposed populations is limited. Methods. Fertility was examined in 1349 male battery plant employees and in 9596 reference company employees over a follow-up of 25 949 and 183 414 person years respectively. The cohorts were identified by records in a national pension fund and information on births was obtained from the Danish Population Register. In a subset of the battery worker cohort, the average level of lead in blood was 35.9 mu g/dl (4639 blood samples on 1654 person years in 400 workers; SD 13.0; range 3-125). The birth rate was analysed by logistic regression on occupational exposure and several extraneous determinants (age, parity, calendar year, and previous children). Results. The birth-rate was not reduced in years at risk from exposure to lead in comparison with years not-at-risk; either in comparison with not-at-risk years within the battery plant cohort (odds ratio [OR] = 0.997, 95% confidence interval [CI] : 0.8-1.13), or in comparison with the external reference population (OR = 0.983, 95% CI : 0.87-1.11). Conclusions. Inorganic lead seems not to impair fertility among Danish battery workers. This finding does not rule out that the time taken to achieve a pregnancy is increased among battery workers because most pregnancies in Denmark are planned.