**1.5.1 Polychlorinated Biphenyls (PCB)**

PCB make up a group of synthetic organic chemicals containing about 200 individual compounds. Some PCB bind to ERs and consequently PCB may exert their toxic effects through estrogenic activity (McKinney & Waller, 1998). Alternatively, some PCB may produce reproductive toxicity through the production of free radicals. Rats exposed to mixtures of PCB demonstrated decreased superoxide dismutase and catalase activity in the testes following exposure (Peltola et al., 1994). PCB congeners have different mechanisms of action and therefore different effects on biological systems. Longitudinal studies of children with in utero or lactational exposure to PCB and other environmental chemicals are essential to assess the long-term effects of endocrine disruption. Prenatal and lactational exposure to PCB may exert adverse effects on male reproduction during subsequent adulthood. A wellstudied population exposed to PCB/PCDF-contaminated rice oil (Yu-Cheng exposure; Taiwan 1978–79) was followed to determine effects on male reproductive health. Median serum PCB levels measured in Yu-Cheng mothers was 26.8 ng/ml: a relatively high PCB exposure that would be expected to affect fetal development. Sexual development and semen quality were evaluated in Yu-Cheng sons, aged 16 yr and older. Seminal volume and sperm concentration were not different between exposed and control boys. However, proportions of sperm with normal morphology and motility were reduced in exposed boys (Guo et al., 2000). The effects of PCB exposure on semen quality in men from the general population appear to affect differentiation of spermatids (spermiogenesis) and posttesticular development (sperm maturation), which would manifest as decreased sperm morphology and motility, respectively. Further studies of PCB exposure—both individual congeners and PCB mixtures—and sperm parameters are required.
