Environmental tobacco smoke effects

  What are the dangers of environmental tobacco smoke (ETS)?

ETS, also known as passive smoking or secondhand smoke, occurs when nonsmokers inhale other people’s tobacco smoke. This includes mainstream smoke (smoke that is inhaled and then exhaled into the air by smokers) and sidestream smoke (smoke that comes directly from the burning tobacco in cigarettes). ETS contains the same harmful chemicals as the smoke that smokers inhale. In fact, because sidestream smoke is formed at lower temperatures, it contains even larger amounts of some toxic and cancer-causing substances than mainstream smoke.

There is strong evidence that ETS causes serious damage to human health. ETS causes about 3,400 lung cancer deaths and about 46,000 deaths from heart disease each year in healthy nonsmokers who live with smokers. It can also affect nonsmokers by causing asthma and other respiratory problems, eye irritation, headaches, nausea, and dizziness. Children whose parents smoke are more likely to suffer from asthma, pneumonia, bronchitis, ear infections, coughing, wheezing, and increased mucus production. Babies of parents who smoke have a greater chance of dying of sudden infant death syndrome (SIDS). Pregnant women exposed to ETS are at risk for having a low birth weight baby and may also be at risk for pre-term delivery and miscarriage.

An issue that continues to be an active focus of scientific research is whether secondhand smoke may increase the risk of breast cancer. Both mainstream and secondhand smoke contain about 20 chemicals that, in high concentrations, cause breast cancer in rodents. Chemicals in tobacco smoke reach breast tissue and are found in breast milk.

The evidence regarding secondhand smoke and breast cancer risk in human studies is controversial, at least in part because the risk has not been shown to be increased in active smokers. One possible explanation for this is that tobacco smoke may have different effects on breast cancer risk in smokers and in those who are just exposed to smoke.

A report from the California Environmental Protection Agency in 2005 concluded that the evidence regarding secondhand smoke and breast cancer is "consistent with a causal association" in younger, mainly premenopausal women. The 2006 US Surgeon General’s report, The Health Consequences of Involuntary Exposure to Tobacco Smoke, concluded that there is "suggestive but not sufficient" evidence of a link at this point. In any case, women should be told that this possible link to breast cancer is yet another reason to avoid contact with secondhand smoke.

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