High PCBs linked to lower testosterone in Mohawk boys

by Environmental Health News Staff

A new study has linked PCBs exposure to the production of lower amounts of testosterone in Onkwehon:we boys along the St. Lawrence River.

Because they eat a lot of locally caught fish, the Akwesasne Mohawks, who live on territory between upstate New York, Ontario and Quebec, are highly exposed to banned industrial compounds called polychlorinated biphenyls, or PCBs.

The higher the exposure, the lower the testosterone levels, according to the new study of 127 Mohawk boys between 10 and 17 years old. A 10 percent increase in exposure to PCBs was associated with a 5.6 percent reduction in testosterone.

“Exposure to PCBs, particularly the more highly persistent congeners, may negatively influence testosterone levels among adolescent males,” the University at Albany researchers concluded in their study, which was published online in the journal Environmental Health Perspectives.

A similar link was found between PCBs and Mohawk men a few years ago. It is not known how the Mohawk boys’ testosterone levels compare with other populations, or whether the boys with the reduced hormones are experiencing any health effects. However, disruption of hormones during adolescence is considered worrisome because it may have long-term repercussions in adulthood, particularly for fertility and reproductive diseases.

The analysis was based on 16 types of PCBs that were found in more than half of the boys. PCBs, which were used in large volumes in electrical equipment, were banned in the late 1970s but break down very slowly in the environment and build up in food webs. Several species of fish near the Akwesasne reservation have high PCB levels considered unsafe for consumption.

“Of the 16 congeners, the more persistent ones were related to testosterone while the less persistent ones, possibly reflecting more recent exposure, were not,” the researchers wrote. The boys’ blood samples were taken by trained Mohawk staff between 1996 and 2000.

Unlike PCBs, when DDE (a breakdown product of the pesticide DDT) increased 10 percent, testosterone increased 5.2 percent. That change was not, however, considered statistically significant.

Other hormone-disrupting effects have been linked to PCBs and DDT in previous studies of lab animals and human populations.

The St. Lawrence River and its tributaries have been contaminated by a variety of industries since the 1950s. The Akwesasne community is near a federal Superfund site and two state hazardous waste cleanup sites.

To read the complete text of the report, please visit http://ehp.niehs.nih.gov/1205984/

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