Sperm Abnormalities in Men Exposed to PCBs and PCDFs

George H. Lambert, MD
University of Medicine and Dentistry of New Jersey
NIEHS Grant R01ES11256

Background: Polychlorinated biphenyls (PCBs) were 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 by much of the world. However, because of their persistence, they are among the most ubiquitous man-made environmental contaminants and are detectable in most human beings worldwide. Polychlorinated dibenzofurans (PCDFs) are produced when PCBs are burned and are equally persistent and toxic.

There are many instances of accidental poisonings from exposure to PCBs. One such incident occurred during a six-month period in Taiwan in 1978-1979. The poisoning was traced back to contaminated cooking oil. PCBs had leaked from heat exchangers into the finished oil product. The PCBs were partially degraded by the heat, which produced PCDFs and other chlorinated multi-ring compounds. Approximately 2,000 people consumed the contaminated oil in what became known as the Yucheng or "poison oil" incident. 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 morphology, reduced motility, and reduced fertility; however effects of post-natal exposures to PCBs/PCDFs are less well documented. The study described below assessed the sperm quality of men directly exposed to PCBs and PCDFs in the Yucheng incident.

Advance: As in the previous study, directly exposed men exhibited higher abnormal sperm morphology than controls. A standard measure of fertility, the ability of sperm to penetrate hamster oocytes, was also lower in the directly exposed men, just as it was in the earlier study. Other semen characteristics were similar between exposed and control subjects.

Implication: This is the first study to show adverse effects in sperm from men directly exposed to PCBs and PCDFs. These findings are compatible with a previous study of prenatally exposed men and also with animal studies investigating similar compounds. The male-to-female offspring ratio was reduced in Yucheng men exposed before age 20 years. The current data suggest 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.

Citation: Hsu PC, Huang W, Yao WJ, Wu MH, Guo YL, Lambert GH. Sperm changes in men exposed to polychlorinated biphenyls and dibenzofurans. JAMA. 2003 Jun 11;289(22):2943-4.