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AbstractThe National Institute for Occupational Safety and Health (NIOSH) has determined that environmental tobacco smoke (ETS) is potentially carcinogenic to occupationally exposed workers. In 1964, the Surgeon General issued the first report on smoking and health, which concluded that cigarette smoke causes lung cancer. Since then, research on the toxicity and carcinogenicity of tobacco smoke has demonstrated that the health risk from inhaling tobacco smoke is not limited to the smoker, but also includes those who inhale ETS. ETS contains many of the toxic agents and carcinogens that are present in mainstream smoke, but in diluted form. Recent epidemiologic studies support and reinforce earlier published reviews by the Surgeon General and the National Research Council demonstrating that exposure to ETS can cause lung cancer. These reviews estimated the relative risk of lung cancer to be approximately 1.3 for a nonsmoker living with a smoker compared with a nonsmoker living with a nonsmoker. In addition, recent evidence suggests a possible association between exposure of nonsmokers to ETS and an increased risk of heart disease. Although these data were not gathered in an occupational setting, ETS meets the criteria of the Occupational Safety and Health Administration (OSHA) for classifying substances as potential occupational carcinogens [Title 29 of the Code of Federal Regulations, Part 1990]. NIOSH therefore recommends that ETS be regarded as a potential occupational carcinogen in conformance with the OSHA carcinogen policy, and that exposures to ETS be reduced to the lowest feasible concentration. Employers should minimize occupational exposure to ETS by using all available preventive measures. Potential for Occupational ExposureApproximately 29% of the U.S. adult population smokes cigarettes, and exposure to ETS is common [DHHS 1989]. Many people who report no exposure to ETS have low concentrations of cotinine (a metabolite of nicotine) in their urine, indicating exposure. The average concentration of cotinine in the urine of nonsmokers has been reported to be approximately 8 ng/ml compared with approximately 1,200 ng/ml in smokers [Cummings et al. 1990]. The National Research Council (NRC) estimated that nonsmokers exposed to ETS averaged 25 ng of urinary cotinine/ml, and active smokers averaged 1,825 ng/ml [NRC 1986]. Husgafvel-Pursiainen et al. [1987] found that nonsmoking restaurant workers had an average urinary cotinine concentration of 56 ng/ml, and nonsmokers not exposed to ETS had an average concentration of 8.3 ng/ml. Other investigators have shown that nonsmokers living with smokers have approximately two to three times the amount of urinary cotinine as nonsmokers living with nonsmokers [Haley et al. 1989]. ConclusionsIn 1964 the Surgeon General concluded that cigarette smoke causes lung cancer. Since that time, additional research on the toxicity and carcinogenicity of tobacco smoke has demonstrated that the health risks from inhaling tobacco smoke are not limited to smokers, but also include those who inhale ETS. ETS contains many of the toxic agents and carcinogens found in MS, but in diluted form. Recent epidemiologic studies support and reinforce the conclusions of the reviews by the Surgeon General and the NRC demonstrating that exposure to ETS can cause lung cancer. These reviews estimated the relative risk for lung cancer to be approximately 1.3 for nonsmokers living with smokers compared with nonsmokers living with nonsmokers. In addition, recent evidence also suggests a possible association between exposure to ETS and an increased risk for heart disease in nonsmokers. The recent epidemiologic studies (including those associating ETS with other adverse health effects) point to a pattern of health effects that is similar for both smokers and nonsmokers exposed to ETS. NIOSH recognizes that these recent epidemiologic studies have several shortcomings: lack of objective measures for characterizing and quantifying exposures, failure to adjust for all confounding variables, potential misclassification of exsmokers as nonsmokers, unavailability of comparison groups that have not been exposed to ETS, and low statistical power. Nonetheless, NIOSH has determined that the collective weight of evidence (i.e., that from the Surgeon General's reports, the similarities in composition of MS and ETS, and the recent epidemiologic studies) is sufficient to conclude that ETS poses an increased risk of lung cancer and possibly heart disease to occupationally exposed workers. The epidemiologic data are not sufficient to draw conclusions about other health effects such as cervical cancer, ischemic stroke, spontaneous abortion, and low birthweight. RecommendationsSeveral systems exist for classifying a substance as a carcinogen. Such classification systems have been developed by NTP [1989], IARC [1987], and OSHA [29 CFR 1990]. NIOSH considers the OSHA classification system (Identification, Classification, and Regulation of Potential Occupational Carcinogens [29 CFR 1990], also known as the OSHA carcinogen policy) the most appropriate for use in identifying occupational carcinogens.†† The Surgeon General has concluded that cigarette smoke causes lung cancer as well as heart disease. Table 1 lists 21 known or suspected carcinogens, cocarcinogens, and tumor promoters identified as components of ETS and MS in analytical studies. Furthermore, a large body of evidence indicates that exposure to ETS has produced lung cancer in nonsmokers. NIOSH therefore considers ETS to be a potential occupational carcinogen in conformance with the OSHA carcinogen policy [29 CFR 1990]. The risk of developing cancer should be decreased by minimizing exposure to ETS. Employers should therefore assess conditions that may result in worker exposure to ETS and take steps to reduce exposures to the lowest feasible concentration. Methods for Controlling Involuntary Exposure to ETSWorkers should not be involuntarily exposed to tobacco smoke. To prevent worker exposures to any hazardous substance, employers should first eliminate hazardous workplace emissions at their source. If elimination is not possible, emissions should be removed from the pathway between the source and the worker [NIOSH 1983]. Therefore, the best method for controlling worker exposure to ETS is to eliminate tobacco use from the workplace and to implement a smoking cessation program. Until tobacco use can be completely eliminated, employers should protect nonsmokers from ETS by isolating smokers. Methods for eliminating tobacco use from the workplace and isolating smokers are described here briefly. Eliminating Tobacco Use from the WorkplaceWorker exposure to ETS is most efficiently and completely controlled by simply eliminating tobacco use from the workplace. To facilitate elimination of tobacco use, employers should implement smoking cessation programs. The Association of Schools of Public Health (ASPH) has recommended the following strategy for smoking cessation [NIOSH 1986]. Specifically, management and labor should work together to develop appropriate nonsmoking policies that include some or all of the following:
Further information regarding workplace smoking policies and smoking cessation programs can be found in No Smoking: A Decision Maker's Guide to Reducing Smoking at the Worksite [American Cancer Society et al. 1985]. [Note: OSHA and NIOSH use "environmental tobacco smoke" (ETS) and "secondhand smoke" (SHS) to mean the same.]
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