Although most studies have failed to detect a link between overall exposure to pollutants called PCBs and an increased risk of breast cancer, the results of a new study from Laval University in Quebec suggest that high levels of specific PCBs may be linked to the disease.
PCBs, or polychlorinated biphenyls, are a class of chemicals with a variety of industrial and commercial applications. Because of concerns about the health effects of the chemicals, PCBs were banned in the US and Canada two decades ago. The chemicals still linger in the environment and are present in the food chain, particularly in fatty foods.
During the past decade, there have been many studies of the possible link between exposure to PCBs and an increased risk of breast cancer. Most studies did not detect a link between high levels of the chemicals and breast cancer, but most of the studies looked at overall levels of PCBs, not individual chemicals.
The researchers examined the relationship between breast cancer risk and 14 individual PCBs in 314 women with breast cancer and a group of 523 healthy women. Levels of two PCBs--PCB 118 and PCB 156--were linked to a 60% to 80% greater risk of breast cancer. This relationship was more pronounced in premenopausal women.
The study also found that women with high levels of a combination of three PCBs that mimic the cancer-causing chemical dioxin--PCBs 105, 118 and 156--were about twice as likely to have breast cancer. This risk was also greater in premenopausal women.
These results do not confirm a link between PCBs and breast cancer risk, but they do call for more research on the topic.
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