The Institute of Medicine (IOM), part of the National Academy of Sciences, does research and offers expert guidance on health issues to the U.S. government and the public. The IOM released a report called "Breast Cancer and the Environment" at the 2011 San Antonio Breast Cancer Symposium.
A panel of 24 experts, most from university medical centers, researched and wrote the report, which was based on current research on factors that may be linked to breast cancer.
The report listed a number of factors that are definitely linked to higher breast cancer risk:
- using combination hormone replacement therapy (HRT); combination HRT contains both estrogen and progesterone
- exposure to unnecessary radiation from x-rays, CAT scans, or other imaging tests
- being overweight or obese after menopause
- drinking alcohol
A link between smoking and breast cancer is likely, but not completely certain because some studies didn't find a link.
Secondhand smoke, nighttime shift work, and exposure to the chemicals benzene, ethylene oxide, or 1,3-butadiene (exposure to these chemicals can happen in some work settings, from breathing car exhaust, from pumping gas, or by inhaling tobacco smoke) may be linked to higher breast cancer risk, but the experts weren't completely certain.
Bisphenol A (BPA), a chemical common in plastic containers and the lining of cans, could have a link to breast cancer based on what's known about BPA's effects in animal studies. But more research is needed to prove a definitive link to breast cancer.
Hair dyes and radiation from cell phones and microwaves are not linked to higher breast cancer risk.
Getting enough exercise (the American Cancer Society recommends women who've been diagnosed with breast cancer exercise at least 4 hours per week) is linked to lower breast cancer risk.
The report looked at many other possible environmental factors and circumstances that might be linked to higher breast cancer risk. The experts said that while there were scientific reasons to suspect links between several environmental factors and breast cancer risk, the available evidence wasn't strong enough to draw any conclusions.
A free prepublication copy of Breast Cancer and the Environment: A Life Course Approach is available for download.
In the Breastcancer.org Lower Your Risk section you can learn much more about breast cancer risk and the steps you can take to keep your risk of breast cancer as low as it can be.