Environmental tobacco smoke (ETS) is the combination of two forms of smoke from burning tobacco products:
More than 4,000 individual compounds have been identified in tobacco and tobacco smoke. Among these are about 60 compounds that are carcinogens, tumor initiators (substances that can result in irreversible changes in normal cells), and tumor promoters (substances that can lead to tumor growth once cell changes begin). Some of these compounds are tar, carbon monoxide, hydrogen cyanide, phenols, ammonia, formaldehyde, benzene, nitrosamine, and nicotine.
The exposure of nonsmokers to ETS is referred to as involuntary smoking, passive smoking, and secondhand smoke. Nonsmokers who are exposed to ETS absorb nicotine and other compounds just as smokers do, and the greater the exposure to ETS, the greater the level of these harmful compounds in the body.
Although the smoke to which an involuntary smoker is exposed is less concentrated than that inhaled by smokers, research has demonstrated that the health risk from inhaling smoke is significant. For example, scientists estimate that ETS causes about 3,000 lung cancer deaths each year.
How Strong Is the Evidence Linking ETS With Lung Cancer?
In 1986, two reports were published on the association between ETS exposure and adverse health effects in nonsmokers: one by the U.S. Surgeon General and the other by the Expert Committee on Passive Smoking, National Academy of Sciences' National Research Council (NAS/NRC). Both of these reports concluded that:
More recent epidemiologic studies support and reinforce these earlier reports. The firmly established causal relationship between lung cancer and mainstream smoke, coupled with the chemical similarities between ETS and the smoke inhaled by smokers, led researchers to conclude that involuntary smoking is likely to have similar effects on the lung. In light of the widespread presence of ETS in both the home and workplace and its absorption by the body, the U.S. Environmental Protection Agency (EPA) released a report in 1992 in which ETS was classified as a Group A carcinogen a category reserved only for the most dangerous cancer-causing agents in humans.
The overall results of 30 epidemiologic studies of lung cancer and involuntary smoking further justify a Group A classification. In these studies, female never-smokers who are married to smokers are compared with female never- smokers who are married to nonsmokers. Higher exposures cause higher risks, and people whose spouses smoke in the home face a higher risk than that of people whose spouses do not smoke at home. In studies of ETS in the workplace, exposures are often even greater than exposure at home from spousal smoking.
While the EPA report focuses only on the respiratory health effects of involuntary smoking, there may be other health effects of concern as well. Recent studies suggest that ETS exposure also may be a risk factor for cardiovascular disease. In addition, a few studies link ETS exposure to types of cancer other than lung.
ETS Exposure in Infants and Children
Studies dating from the early 1970s have consistently shown that children and infants exposed to ETS in the home have significantly elevated rates of respiratory symptoms and respiratory tract infections. More than 50 recently published studies confirm these previous conclusions:
These findings prompted recommendations that ETS be eliminated from the environment of small children. Thus, smoking should not be allowed in day care centers, nurseries, or other settings where infants and young children are cared for.
ETS Exposure in Nonsmokers with Existing Health Problems
ETS can worsen existing pulmonary symptoms in people with asthma and chronic bronchitis, as well as for people with allergic conditions. Even individuals who are not allergic can suffer eye irritation, sore throat, nausea, and hoarseness. Contact lens wearers can find tobacco smoke very irritating.
Public Policies Restricting Smoking
Following the release of the Surgeon General's report and the NAS/NRC review, many new laws, regulations, and ordinances were enacted that severely restrict or ban public smoking. With the release of the EPA report, many more such laws can be expected:
Additional Resources About the Effects of ETS
The NAS/NRC report "Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects" (POD #318) is published by the National Academy Press. It may be ordered from the National Academy Press, Box 285, 2101 Constitution Avenue NW, Washington, DC 20055; the telephone number is 202-334-3313, and the toll-free number is 1-800-624-6242. The price is $58.25 plus $4.00 for shipping and handling per order. Orders must be prepaid by check or charged to VISA, MasterCard, or American Express.
"The Health Consequences of Involuntary Smoking: A Report of the Surgeon General" (stock number 017-001-00458-8) is available for $11.00 from the U.S. Government Printing Office, Post Office Box 371954, Pittsburgh, PA 15250-7954; the telephone number is 202-783-3238.
The EPA report "Respiratory Health Effects of Passive Smoking: Lung Cancer and Other Disorders" (stock number 055-000-00407-2) is available for $29.00 from the U.S. Government Printing Office, Post Office Box 371954, Pittsburgh, PA 15250-7954; the telephone number is 202-783-3238. The summary of this report and additional information on ETS are available free of charge from the U.S. Environmental Protection Agency, Indoor Air Quality, Post Office Box 37133, Washington, DC 20013-7133; the toll-free telephone number is 1-800-438-4318.
The NIOSH report "Current Intelligence Bulletin 54, Environmental Tobacco Smoke in the Workplace" is available from NIOSH's Office of Information, 4676 Columbia Parkway/ Mailstop C-19, Cincinnati, OH 45226. The toll-free telephone number is 1-800-35-NIOSH (1-800-356-4674).
The Office of Smoking and Health, Centers for Disease Control and Prevention, distributes materials on ETS. The Office can be contacted at 1600 Clifton Road, Rhodes Building/NE Mail Stop K-50, Atlanta, GA 30341-3724; the telephone number is 404-488-5705. The National Cancer Institute also publishes a free publication, "I Mind If You Smoke," which offers suggestions to nonsmokers about how to protect themselves from exposure to ETS at home, at work, and in public places.
Additional information on lung disease, cancer, and smoking is provided by the American Lung Association and the American Cancer Society. Local chapters of these organizations are listed in telephone directories.