New research published in the open access journal, Environmental Health: a Global Access Science Source suggests that women exposed to polychlorinated biphenyls are less likely to give birth to boys. The results come from a study of mothers and fathers around the Great Lakes region of the United States who have eaten large quantities of contaminated fish. These findings add to a growing body of evidence suggesting that environmental pollution may be responsible for changes in the proportion of male births around the world.

Contamination of the Great Lakes with polychlorinated biphenyls (PCBs) has led to the concentration of these chemicals in the fatty tissue of fish, particularly large predator species favoured by sport fishermen. PCBs are man-made chemicals, used until the late 1970's as coolants and lubricants. Manufacture of PCBs was stopped in the US over twenty years ago because of concerns about contamination in the environment and effects on health. Eating fish from the Great Lakes has been associated with a reduction in the birth weight of babies, a shortened menstrual cycle, reduced fertility, and neurologic disorders.

For much of the twentieth century the global proportion of male births has been declining. Some animal studies suggest that exposure to PCBs may lower the proportion of male offspring produced by a mother. However human studies have yet to show any conclusive effect of PCBs. In an attempt to examine the effects of PCB consumption on the gender of newborns, Marc Weisskopf from the Harvard School of Public Health and Henry Anderson and Lawrence Hanrahan from the Wisconsin Department of Health and Family Services investigated the PCB levels in the blood of parents from the Great Lakes region.

The researchers interviewed sport fishing charter boat captains to identify those that had eaten large quantities of potentially contaminated fish. Randomly selected members of the community who lived in a similar geographic area
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Contact: Grace Baynes
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BioMed Central
30-Apr-2003

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