Assessment of chemicals affecting the male reproductive system

The reproductive toxicologist must be more concerned with the ability of laboratory models to predict human reproductive hazards and to estimate human health risks. Although more than a hundred chemicals have been reported to affect the reproductive capacity of male laboratory animals, fewer than 15 environmental chemicals have been shown conclusively to affect man and many of these are known mutagens, carcinogens or otherwise generally toxic agents. Pharmacokinetic and adaptive factors must be considered. More attention also needs to be directed towards processes other than spermatogenesis and towards mechanisms of toxicity other than cytotoxicity. The male component necessary for successful reproduction depends on a large variety of biological processes working in concert. The ability to assess chemically-induced reproductive effects needs to be refined and modern molecular and cellular approaches should be developed and validated. This paper summarizes aspects of the pharmacokinetic and adaptive factors involved in testicular toxicity, some current laboratory assessment techniques, and newer test procedures such as monoclonal antibodies for sperm surface proteins and the interspecies (human/hamster) sperm penetration assay.