Health hazards of passive smoking.

"Environmental tobacco smoke" (ETS) is the term used to characterize tobacco combustion products inhaled by nonsmokers in the proximity of burning tobacco. Over 3800 compounds are in tobacco smoke, many of which are known carcinogens. Most ETS exposure is from sidestream smoke emitted from the burning tip of the cigarette. Sidestream smoke is hazardous because it contains high concentrations of ammonia, benzene, nicotine, carbon monoxide, and many carcinogens. Nonsmokers chronically exposed to ETS are believed to assume health risks similar to those of a light smoker. Children of parents who smoke have more respiratory infections, more hospitalizations for bronchitis and pneumonia, and a smaller rate of increase in lung function compared to children of parents who do not smoke, particularly during the first year of life. Among adults with preexisting health conditions such as allergies, chronic lung conditions, and angina, the symptoms of these conditions are exacerbated by exposure to ETS. The acute health effects among healthy adults include headaches, nausea, and irritation of the eyes and nasal mucous membranes. The evidence for a relationship between ETS and cancer at sites other than lung is insufficient to draw any positive conclusions. For lung cancer, studies have consistently shown an excess risk between 10% and 300%, with a summary relative risk of 1.3 (95% confidence interval = 1.1-1.5). A dose-response relation is suggested but difficult to assess completely. Histologic types of lung cancer are generally similar to those most closely associated with active smoking, although other histologic types have also been found. Both excess relative risks and the dose responses are underestimates of the true excess risk and of the range of dose-response effect. Although the temporal relationship between exposure and disease occurrence is established, many questions are unanswered. The findings are consistent with many known biologic effects of active smoking and are partially analogous to the biologic effects of direct smoke inhalation. As many as 5000 nonsmokers are estimated to die annually from lung cancer as a result of exposure to ETS. There is great potential for prevention of these premature deaths. The two major preventive actions are (a) eliminating the source by reducing the amount of direct smoking and (b) limiting the level of exposure by restricting where tobacco can be smoked. Specific preventive actions include smoking cessation, smoking prevention, restriction of advertising, increased taxation on tobacco, and adoption of stringent nonsmoking policies in the workplace, schools, and public places.(ABSTRACT TRUNCATED AT 400 WORDS)