ANR UPDATE, 33(4), Winter 2014


Breast Cancer, Smoking, and Secondhand Smoke
Guest Editorial: Dr. Stanton Glantz

It has been nearly 10 years since the California Environmental Protection Agency (Cal-EPA) concluded that secondhand smoke caused breast cancer in younger, premenopausal women. Cal-EPA reached this conclusion in its 2005 report, "Proposed Identification of Environmental Tobacco Smoke as a Toxic Air Contaminant," a thorough review of the available epidemiological evidence and knowledge about how the chemicals in tobacco smoke cause breast cancer in both animals and humans. The overall increase in the risk of breast cancer in younger women exposed to secondhand smoke is about 70% compared to women who do not suffer such exposures.

The following year, in 2006, the US Surgeon General (SG) came to the same conclusions that Cal-EPA did about the elevated risk of breast cancer in women exposed to secondhand smoke, but concluded that the evidence that secondhand smoke caused breast cancer was only "suggestive," largely because of a conclusion, reached several years earlier, that active smoking did not cause breast cancer.

Of course, "suggestive" is just one step below "causal" and sensible people would want to avoid involuntary exposure to a pollutant that was "only" very likely to cause breast cancer.

Last January saw the release of the 50th Anniversary Surgeon General's report on Tobacco or Health, which upgraded the evidence for active smoking as a cause of breast cancer to "suggestive" and kept the status of secondhand smoke at "suggestive," despite the fact that the evidence linking both active and passive smoking to breast cancer kept accumulating.

Despite this failure to reach a "causal" conclusion, however, the SG's Report did say: "Sufficient quantitative evidence indicates that smoking - active smoking or passive exposure to smoking - is associated with an increased risk for breast cancer. However, the magnitude of risk is small, and neither active smoking nor passive exposure to smoking constitutes a large risk to the breast health of women."

This remarkable statement leaves open an obvious question: How large would the risk of breast cancer need to be for the SG to start warning women and their employers to live and work in smokefree environments in order to protect them from breast cancer?

After all, everyone agrees that the risk is highest among younger women, those most likely to be forced to breathe secondhand smoke at work in bars and casinos.

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