FERTILITY AMONG A COHORT OF MALE SAWMILL WORKERS EXPOSED TO CHLOROPHENATE FUNGICIDES

The purpose of this study was to determine whether exposure to chlorop henate fungicides and their dioxin contaminants is associated with mal e infertility among sawmill workers, The study was conducted using fer tility data compiled from 26,487 sawmill workers in 14 British Columbi an sawmills. Our analysis was restricted to workers who had been emplo yed for at least 1 continuous year between 1950 and 1985 and to livebi rths born at least 1 year alter the initiation of employment in the pe riod 1955-1988. We assessed fertility trends by internal comparison us ing Mantel-Haenszel rare ratios and by calculating standardized fertil ity ratios using an external and an internal reference population. We identified 19,684 births in the study period. Initially, both external and internal analyses showed that sawmill workers from mills using ch lorophenates had lower fertility than workers employed in mills not us ing chlorophenates. After controlling for time since first hire, howev er, we found no inverse relation between cumulative exposure to chloro phenate fungicides and fertility. Based on the results of our study, t here is little evidence for a reduction in fertility among chlorophena te-exposed sawmill workers in British Columbia. The analyses indicate the importance oi time since hire as a potentially strong confounder i n this type of investigation.