Toxic Infertility

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. 

Reproductive disorders in humans are known to be caused by more than 100 different individual chemicals and are suspected to be caused by some 200 more. Table 23.1 lists some of these compounds and their Kqw values. W As can be seen from this table, many different types of chemicals containing far different functional groups cause reproductive disorders. These include aliphatic and aromatic hydrocarbons, glycol ethers, chlorinated hydrocarbons, pesticides, and heavy metals. Both lipophilic and hydrophilic compounds are contained in the list. Some of the chemicals are rapidly metabolized, whereas others accumulate in adipose tissue and are stored in the body for long periods of time. The mechanisms by which many of these chemicals act remain unknown. 

Infertility rates in both women and men have been continually rising. It is estimated that approximately 50% of human conceptuses fail to reach term. Sperm count concentrations in men have been continually declining over the past 50 years. At the same time, increases in hypspadias, cryp-tochidism, and testicular cancer have further contributed to increasing male infertility. Xenoestrogens have contributed to male infertility as well as to female infertility. Spontaneous abortion rates and preterm births continue to rise, contributing further to 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. 

Reproductive disorders in humans are known to be caused by more than 100 different individual chemicals and suspected to be caused by some 200 more. Table 

Products containing infertility causative ageuts iuclude adhesives, paints, siU-cones, solvents, and the fumes from welding rods that emitted during welding [3]. House dust containing organophosphate flame retardants has been shown to alter hormone levels and decrease sperm quality in men [4]. 

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