DBCP and testicular effects in chemical workers: an epidemiological survey in Midland, Michigan.

The agriculturally important nematocide 1,2-dibromo-3-chloropropane (DBCP) has been implicated as a cause of human male sterility. A survey at the Michigan Division of The Dow Chemical Company included measurements of semen samples, testicular size, and serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone in 232 chemical workers with past potential exposures to DBCP and in 97 nonexposed comparison employees. Potentially exposed groups showed significantly higher, although not abnormal, mean levels of FSH and LH. In the subgroup with the highest potential exposure ending subsequent to 1972, greater duration of exposure correlated with lower sperm count, higher FSH level, and smaller testicular volume. Mean values for this latter time-divided subgroup were not abnormal. The findings are consistent with a testicular effect of DBCP and also with reversibility of that effect over time.