Xenobiotics male infertility

Xenobiotic chemicals are thought to contribute to all these causes of infertility, though the effects of chemical mixtures on infertility have only recently begun to be explored. This chapter examines the effects of chemical mixtures on female and male infertility from the perspectives of the impacts of exposures in adults as well as fetuses. 

Male infertility manifests in several ways. These include sex organ malformation, reduced sperm count, reduced level of seminal fluid, decreased libido, and testicular cancer. Discussions of these conditions, all of which have been attributed to xenobiotic influences (primarily by endocrine disruptors 41 ), follow. 

As discussed earlier, male infertility has been associated with exposures to xenobiotic chemicals. Though affects have been reported for single chemicals, most are based on laboratory testing on animals, since most environmental exposures to humans come from mixtures. Some data, however, has been collected from infertility induced by industrial and environmental exposures. Table 23.3 contains a partial list of chemicals associated with male infertility. I48,58-66 These chemicals include pesticides, heavy metals, and industrial chemicals. 

Exposure to xenobiotics raises the risk of male infertility, breast cancer in females, feminization of male animals and the evolution of antibiotic resistant strains of bacteria. Of particular concern are endocrine disruptors such as polychlorinated biphenyls (PCBs), which are chemicals that at certain doses can interfere with the endocrine (or hormone) system in mammals. These disruptions can cause cancerous tumours, birth defects and other developmental disorders. 

Toxic infertility as used here refers to adverse effects on the reproductive systems of human males and females that result from exposure to xenobiotic single chemicals and chemical mixtures. This infertility may be because of direct toxic effects on the male or female reproductive organs and endocrine systems, or on the developing fetus such that the fetus cannot be either conceived or carried to term after conception. Developmental toxicity, the onset of adverse effects on the developing fetus or child after birth are discussed in Chapter 24. 

Human infertility can result from the action of xenobiotic chemicals on the female reproductive system, the male reproductive system, attack on the fetus, and the induction of effects in utero that are manifest during adulthood, giving rise to a programmed infertility. Spontaneous abortion can ensue when pregnant women are exposed to toxic chemicals such as those in disinfection byproducts produced by the chlorination of drinking water. 

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