Of the environmental factors reviewed, those with the most consistent evidence of a link to higher breast cancer risk are:
"Obviously some risk factors are outside of our influence, but some are under our control," said Dr. Iuliana Shapira, director of the cancer genetics service at Monter Cancer Center in Lake Success, N.Y. "The more CT scans we have, the more likely we are to get cancer. This is a wake-up call."
The connection between smoking and breast cancer is more nebulous, the report said, because of mixed evidence. For several other factors -- including secondhand smoke exposure, nighttime shift work and exposure to the workplace chemicals benzene, ethylene oxide or 1,3-butadiene -- the evidence is less persuasive but suggests a possible link to higher risks.
A breast cancer association with bisphenol A (BPA), which is widely used in plastic containers and food packaging, is biologically plausible, the committee said, but research assessing the risk in humans is lacking. The same is true of pesticides and ingredients in cosmetics and dietary supplements, most of which aren't tested before going to market.
However, research doesn't support a link between the use of hair dyes and non-ionizing radiation -- which is emitted from electronic devices such as cellphones and microwaves -- and breast cancer, the study said.
"I'm impressed that they have taken certain positions that may have not actually been supported by public awareness or understanding, such as cigarette smoking or hair dyes," said Robert Schneider, co-director of the Breast Cancer Research Program and associate director of translational cancer research at NY
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