Fertility of Danish battery workers exposed to lead
Bonde, J.P.; Kolstad, H.
International Journal of Epidemiology 26(6): 1281-1288
1997
ISSN/ISBN: 0300-5771 PMID: 9447408 DOI: 10.1093/ije/26.6.1281Document Number: 273607
This study examined the effects of exposure to lead among battery workers on fertility in Denmark. The research methods were based on an earlier study among metal workers. The sample population included a cohort of 1349 men born in 1940 or after who worked at 3 Danish battery plants between April 1, 1964 and December 31, 1992. The plants were located in different parts of the country. The control population included 9596 workers from 86 Danish manufacturing steel, wooden boat, and plastics products companies. All workers were considered to be exposed to lead during their period of employment. Biological monitoring of blood lead levels (BLLs) was conducted during 1983-88 among 400 workers, or 4639 blood samples. The average BLL was 39.2 mcg/dl. Average BLLs declined slightly during follow-up. More samples were taken from workers with high BLLs. Findings indicate that employment at a Danish battery plant was not associated with any change in fertility, as measured by the birthrate, during either the years of employment or subsequent years. There was no indication that long-term exposure was related to reduced fertility. Reduced fecundity, which is correlated with exposure to lead, may not necessarily result in reduced fertility. Reduced fecundity may be counteracted by an increased number of menstrual cycles exposed to sperm. The most important factors that mediate between reduced fecundity and reduced fertility are the extent of reproductive impairment, the number of desired children, and the timing of initiation of sexual activity during the reproductive period. Several European countries are involved in studies to determine the impact on time-to-pregnancy and semen quality in lead-exposed populations.