Epidemiological Studies On The Relationship Between Semen Quality And Environmental Chemicals: Historic And Contemporary Compounds

Recent reports of downward trends in semen quality and increased rates of developmental urogenital tract anomalies and testicular cancer have raised both scientific and public concern about the potential risk of environmental chemicals to male reproductive health. Of particular concern is whether some contemporary use environmental chemicals alter semen quality. Semen quality refers to both conventional measures, such as sperm concentration, motility and morphology, as well as sperm DNA integrity as assessed by bioassays. Specific toxicants of interest include phthalates and pesticides (primarily insecticides and herbicides), as well as polychlorinated biphenyls (PCBs). The human data on the relationship of semen quality with phthalate and pesticide exposure are limited and does not currently allow for a definitive conclusion on whether adult exposure, at background environmental levels, alters semen quality. However, the epidemiologic data support an inverse association of PCBs with reduced semen quality, specifically reduced sperm motility. The associations found were generally consistent across studies despite a range of PCB levels. In addition to the chemicals discussed in detail, there are additional classes of chemicals that require further study as to their relation with human semen quality. These chemicals include alkylphenols, such as 4-nonylphenol, bisphenol A and the fluorinated organic compounds.