I. The effect of p-nonylphenol, an environmental toxicant with oestrogenic properties, on fertility potential in adult male rats

Infertility is a sad reality and it is now evident that several aspects of male reproductive health have changed for the worse over the past 30-50 years. para-nonylphenol (p-NP), an environmental toxicant with oestrogenic properties, was tested for its effect on male fertility potential. When adult male rats were exposed to 100 mg kg(-1) Q-NP the histological parameters of the seminiferous tubules were adversely affected. Although spermatogenesis was already established in these males at the time exposure commenced, p-NP still had an effect on the histology of the seminiferous tubules. Increasing the level to 250 mg kg(-1) additionally resulted in a smaller weight gain and signs of epididymal toxicity, while 400 mg kg(-1) also impaired testicular mass and sperm count. In the last two groups spermatogenesis was also affected in some animals. Because p-NP had an effect on established spermatogenesis in the rat, one could speculate that the same effects might also occur in humans. It would appear that p-NP had toxic effects on both the testis and epididymis and both structures might be important in impairing male fertility. Bio-accumulation may enhance the negative effects at even lower p-NP concentrations over longer exposure periods than reported here.