The effect of industrial and agricultural pollution on human spermatogenesis.

Dibromochloropropane (DBCP), a liquid nematocidal agent, had been in use since the mid-1950s. In particular, it was used on bananas in tropical and subtropical areas of the World (Central America, Caribbean Islands, Israel...). Although its spermatotoxic effect in rats was discovered in the early 1960s, its deleterious effects on human spermatogenesis were only discovered in 1977 (Whorton et al., 1977). At that time, the workers in a DBCP plant in California noted that there was a paucity of children conceived by the men after each had started to work in DBCP production area. Subsequently to a film on work at the factory, five of these workers had their spermatozoa analysed: all were grossly abnormal (azoospermic or severely oligozoospermic, ,203106/ml). A complete analysis of the 22 men working in this process showed a high correlation between duration of exposure to DBCP and sperm count; a group of men having been working on DBCP production for an average of 8 years exhibited a mean sperm count of 0.23106/ml, while the new workers in this area (average time lag 0.8 years) had a mean sperm count of 933106/ml. The concentrations of follicle stimulating hormone (FSH) and luteinizing hormone (LH) were statistically increased in the first group (Whorton et al., 1979). This study was then repeated on a larger sample of DBCP workers, and finally repeated in other plants (Whorton, 1981). Studies undertaken in 1977–78 all showed that occupational exposure to DBCP has disastrous effects on testicular function, as 14.5% of the subjects were azoospermic and another 21% were oligozoospermic. Subsequent studies on factory workers in Mexico and field workers in Hawaii, Israel and Costa Rica have shown similar results of testicular dysfunction.