Sperm abnormalities in men exposed to PCBs and PCDFs.

Hsu PC, Huang W, Yao WJ, Wu MH, Guo YL, Lambert GH. 2003. Sperm changes in men exposed to polychlorinated biphenyls and dibenzofurans. JAMA 289:2943 2944.

Polychlorinated biphenyls (PCBs) were once commonly used in transformers and other industrial applications because of their superior insulating properties and stability. When the adverse health effects of this class of compounds were discovered in the 1970s, they were banned in much of the world. However, because of their persistence, they are still among the most ubiquitous man-made environmental contaminants and are detectable in most human beings worldwide Polychlorinated dibenzofurans (PCDFs), produced when PCBs are burned, are equally persistent and toxic.

During a six-month period in 1978-1979, approximately 2,000 people in Yucheng, Taiwan, consumed cooking oil contaminated with PCBs and PCDFs. PCBs had leaked from heat exchangers into the finished oil product. The PCBs were partially degraded by the heat, producing PCDFs and other chlorinated compounds A registry of those exposed was created to track adverse health outcomes.

A previous study of prenatally exposed young men born to Yucheng women showed increased abnormal sperm morphology, reduced motility, and reduced fertility. In this research letter, NIEHS grantee George Lambert of the Robert Wood Johnson Medical School-University of Medicine and Dentistry of New Jersey in Piscataway and colleagues assessed the sperm quality of men directly exposed to PCBs and PCDFs in the Yucheng incident. Directly exposed men exhibited higher abnormal sperm morphology than controls and lower ability of sperm to penetrate hamster oocytes, a standard measure of fertility. Other semen characteristics were similar between exposed and control subjects. This is the first study to show adverse effects in sperm from men directly exposed to PCBs and PCDFs.

In the current study, the male-to-female offspring ratio was reduced in Yucheng men who were exposed before the age of 20. This suggests that the reduced capability of oocyte penetration found in this study may be specific to Y chromosome-bearing sperm, but this has not been confirmed and warrants further investigation.