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1
Introduction

Environmental tobacco smoke (ETS) occurs in homes, at workplaces, and in public places. The acute irritating and noxious effects of involuntary exposure to ETS, or “passive smoking,” are well established. Based in part on these irritating properties of ETS, a recent report of the NRC recommended a ban on smoking in the small enclosed spaces of airliner cabins (National Research Council, 1986). More than 20 states and numerous local governments have enacted legislation and policies restricting smoking (1985 information obtained from the Office on Smoking and Health, personal communications). Such public information campaigns and other actions have convinced a large portion of the population that active cigarette smoking is dangerous to health. To many, this also implies that exposure to ETS can affect health. This report, in part, evaluates whether the latter beliefs are warranted. It also makes recommendations for future exposure monitoring and epidemiologic research.

The issues are complex. In some cases the conclusions are uncertain, because much of the scientific data necessary to shed light on these concerns does not exist. This report addresses the following major issues pertaining to ETS:

  • The nature of the smoke. What constitutes ETS? What are the chemicals in ETS and what are the dilutions therein? There are two physical phases of smoke: particulate phase and vapor phase. What chemicals are in each phase? Are any of these chemicals carcinogenic or toxic, as determined in bioassays?



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Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects 1 Introduction Environmental tobacco smoke (ETS) occurs in homes, at workplaces, and in public places. The acute irritating and noxious effects of involuntary exposure to ETS, or “passive smoking,” are well established. Based in part on these irritating properties of ETS, a recent report of the NRC recommended a ban on smoking in the small enclosed spaces of airliner cabins (National Research Council, 1986). More than 20 states and numerous local governments have enacted legislation and policies restricting smoking (1985 information obtained from the Office on Smoking and Health, personal communications). Such public information campaigns and other actions have convinced a large portion of the population that active cigarette smoking is dangerous to health. To many, this also implies that exposure to ETS can affect health. This report, in part, evaluates whether the latter beliefs are warranted. It also makes recommendations for future exposure monitoring and epidemiologic research. The issues are complex. In some cases the conclusions are uncertain, because much of the scientific data necessary to shed light on these concerns does not exist. This report addresses the following major issues pertaining to ETS: The nature of the smoke. What constitutes ETS? What are the chemicals in ETS and what are the dilutions therein? There are two physical phases of smoke: particulate phase and vapor phase. What chemicals are in each phase? Are any of these chemicals carcinogenic or toxic, as determined in bioassays?

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Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects Factors affecting exposure and the assessment of exposure. To what extent is the nonsmoker exposed to harmful chemicals that can be measured in ETS? How can we measure exposure to ETS? Can ambient monitoring be used in epidemiological studies? How reliable is questionnaire information? What constitutes the dose a person may receive? Are there objective measures of dose received, such as tobacco-smoke-specific biological markers? What choices and reasons for choice are there among the markers? Effects of exposure. What are the health effects, if any, consequent to exposure to ETS? Are these health effects related to discomfort or irritant effects only, or more serious disease? Are the potential health effects reversible when exposure ceases? What are the data from human studies? Do interactions with other environmental agents at workplaces or in homes need to be considered? Are there biologically plausible explanations for the various effects ascribed to ETS exposure? The report considers sensitive populations such as children, pregnant women, older persons, and those with persisting respiratory illnesses. It does not consider the established effects on the fetus carried by a pregnant, smoking woman because this is not an instance in which a nonsmoking individual breathes ETS generated by other people. However, a pregnant, nonsmoking woman might be affected by exposure to ETS, as may her fetus. The health effects considered include respiratory symptoms and lung function, and other respiratory ailments (especially in children), such as asthma and allergic responses, cancer at various sites, and cardiovascular disease, among others. Some attention is paid to irritation, annoyance, and associated responses. DEFINITIONS Environmental tobacco smoke (ETS) originates from the smoldering end of the tobacco product in between puffs, known as sidestream smoke (SS), and from the smoker’s exhaled smoke. [The smoke that the smoker inhales is known as mainstream smoke (MS).] Other contributors to ETS include minor amounts of smoke that escape during the puff-drawing from the burning cone and some vapor-phase components that diffuse through the cigarette paper into the environment. These various components are released into the environment and are diluted by ambient air. They

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Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects may also aggregate with pollutants already in the environment and thereby change character. The composition of this complex mixture, known as ETS, has different physicochemical characteristics than the MS. There are various terms in the literature that refer to the inhalation of ETS by nonsmokers, e.g., “passive smoking,” “involuntary smoking,” and “breathing other people’s smoke.” We will refer to the inhalation of ETS by using the terms “passive smoking” and “exposure to ETS by nonsmokers” interchangeably. TRENDS IN CIGARETTE USAGE Exposure of nonsmokers to ETS is a function of several variables, one of which is the number of active smokers with whom the nonsmoker comes into contact throughout some period of time. The percent of the population who smoke steadily increased over the first two-thirds of this century but has declined more recently. In 1980, 32% of the adult population considered themselves to be cigarette smokers (U.S. Department of Commerce, 1984). This percentage, now roughly equal for men and for women, reflects a reduction of almost one-third in men since the publication of the first Surgeon General’s Report on Smoking and Health in 1964 (U.S. Public Health Service, 1964). Figure 1–1 shows the trends in cigarette usage between 1955 and 1985 for males and females. Table 1–1 gives cigarette consumption since 1900. Table 1–2 illustrates an overall increase in cigar and pipe smoking, followed by a decline during the past decade. The actual probability of exposure to ETS is complex, affected by ventilation rates, size of houses, restrictions on where tobacco products may be smoked, and changes in the cigarette itself. The consequence of Figure 1–1 is that the general probability of being exposed to some ETS for the nonsmoker has increased until quite recently. The magnitude of exposure to ETS will depend upon the number of cigarettes and/or cigars and pipes smoked in a given environment, as well as other factors such as ventilation. Light smokers are more likely to stop smoking than heavy smokers, which might explain why over the past 30 years the number of cigarettes per smoker and the total consumption (Figure 1–2) have not declined as rapidly as the percentage of people who smoke (see also cigar and loose tobacco consumption in Table 1–2). From a peak consumption in the early 1960s, there has been a decline of

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Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects FIGURE 1–1 Percentage of current smokers in the United States. Adult population, by sex, 1955–1983. From Shopland and Brown (1985). 20% in the per capita (U.S.) consumption of cigarettes (Shopland and Brown, 1985). These data, however, are averaged over the total U.S. population, including smokers and nonsmokers. Among persons who consider themselves smokers, the cigarette consumption per adult smoker actually has increased from 27.3 to 30.0 cigarettes per day. Table 1–3 demonstrates that, for both sexes, the percent of smokers who are heavy smokers has steadily increased over the past 30 years. Therefore, the consumption per active smoker indicates that the nonsmoker who has close contact with a smoker may be exposed to greater amounts of smoke in 1985 than in 1955, although the total number of hours a nonsmoker is exposed to ETS would have declined. Counteracting this trend of increased exposure has been the trend of reduction in amount of tobacco used to fill each cigarette. Physical changes of the leaf due to modern methods of processing, the use of filter tips (United States, >90% of all cigarettes since

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Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects TABLE 1–1 U.S. Cigarette Consumption, 1900 to 1985a Year Total Billions Number Per Capita, 18 Years and Older Year Total Billions Number Per Capita, 18 Years and Older Year Total Billions Number Per Capita, 18 Years and Older 1900 2.5 54 1930 119.3 1,485 1960 484.4 4,171 1901 2.5 53 1931 114.0 1,399 1961 502.5 4,266 1902 2.8 60 1932 102.8 1,245 1962 508.4 4,265 1903 3.1 64 1933 111.6 1,334 1963 523.9 4,345 1904 3.3 66 1934 125.7 1,483 1964 511.3 4,195 1905 3.6 70 1935 134.4 1,564 1965 528.8 4,259 1906 4.5 86 1936 152.7 1,754 1966 541.3 4,287 1907 5.3 99 1937 162.8 1,847 1967 549.3 4,280 1908 5.7 105 1938 163.4 1,830 1968 545.6 4,186 1909 7.0 125 1939 172.1 1,900 1969 528.9 3,993 1910 8.6 151 1940 181.9 1,976 1970 536.5 3,985 1911 10.1 173 1941 208.9 2,236 1971 555.1 4,037 1912 13.2 223 1942 245.0 2,585 1972 566.8 4,043 1913 15.8 260 1943 284.3 2,956 1973 589.7 4,148 1914 16.5 267 1944 296.3 3,039 1974 599.0 4,141 1915 17.9 285 1945 340.6 3,449 1975 607.2 4,123 1916 25.2 395 1946 344.3 3,446 1976 613.5 4,092 1917 35.7 551 1947 345.4 3,416 1977 617.0 4,051 1918 45.6 697 1948 358.9 3,505 1978 616.0 3,967 1919 48.0 727 1949 360.9 3,480 1979 621.5 3,861 1920 44.6 665 1950 369.8 3,522 1980 631.5 3,851 1921 50.7 742 1951 397.1 3,744 1981 640.0 3,840 1922 53.4 770 1952 416.0 3,886 1982 634.0 3,753 1923 64.4 911 1953 408.2 3,778 1983 600.0 3,502 1924 71.0 982 1954 387.0 3,546 1984 600.4b 3,461b 1925 79.8 1,085 1955 396.4 3,597 1985 595.0c 3,384c 1926 89.1 1,191 1956 406.5 3,650   1927 97.5 1,279 1957 422.5 3,755 1928 106.0 1,366 1958 448.9 3,953 1929 118.6 1,504 1959 467.5 4,073 aIncludes overseas forces, 1917–1919 and 1940 to date. Commodity Economics Division, Economic Research Service, USDA. bSubject to revision. cEstimated. SOURCE: U.S. Department of Agriculture, 1985.

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Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects FIGURE 1–2 Total cigarette consumption (domestic sales), 1955–1985. 1978; Griese, 1984), and variations in the composition of tobacco blends for cigarettes (Norman, 1982) have made this reduction possible. In 1956, the U.S. average tar and nicotine yields were 38.4 mg and 2.69 mg, respectively. Since then, tar and nicotine yields have steadily decreased to 13.2 mg tar and 0.95 mg nicotine in 1980 (The Tobacco Institute, 1981). However, tar and nicotine yields in the SS of cigarettes have not significantly changed except

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Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects TABLE 1–2 U.S. Consumption of Cigars and Tobacco for Pipes and Hand-rolled Cigarettes Year Cigars, millions Tobacco, Mn. lba Year Cigars, millions Tobacco, Mn. lba Year Cigars, millions 1920 8,609 — 1950 5,608 104.3 1980 5,386 1921 7,435 — 1951 5,778 97.4 1981 5,231 1922 7,527 — 1952 6,037 92.9 1982 4,901 1923 7,505 — 1953 6,107 84.3 1983 4,884 1924 7,189 — 1954 6,024 81.2   1925 6,949 — 1955 6,078 77.8 1926 7,008 — 1956 6,039 70.0 1927 7,008 — 1957 6,194 68.9 1928 6,874 — 1958 6,586 74.4 1929 6,972 — 1959 7,377 71.9 1930 6,272 — 1960 7,434 72.2 1931 5,656 — 1961 7,083 72.7 1932 4,724 — 1962 7,103 69.8 1933 4,553 — 1963 7,434 69.7 1934 4,818 — 1964 9,899 81.7 1935 4,943 — 1965 8,949 69.8 1936 5,362 — 1966 8,610 68.6 1937 5,516 — 1967 8,403 66.4 1938 5,294 — 1968 8,331 69.6 1939 5,469 — 1969 8,579 68.3 1940 5,491 — 1970 8,881 74.0 1941 5,933 — 1971 8,830 69.5 1942 6,339 — 1972 11,125 66.8 1943 5,350 — 1973 11,126 59.5 1944 4,878 — 1974 9,339   1945 5,027 — 1975 8,663 1946 5,929 — 1976 7,492 1947 5,706 — 1977 6,792 1948 5,860 — 1978 6,231 1949 5,625 — 1979 5,706 aTobacco for pipes and hand-rolled cigarettes, not available prior to 1950. SOURCES: Lee, 1975; Tobacco Reporter, 1984.

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Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects TABLE 1–3 Number of Cigarettes Smoked per Day, as a Percentage of Current Smokers, by Sex   Less Than 15 15–24 25 or More Males   1965 30.1 45.7 24.1 1976 24.9 44.4 30.7 1980 24.2 41.7 34.2 1983 23.5 42.9 33.6 Females   1965 46.2 40.8 13.0 1976 37.6 43.4 19.0 1980 34.7 42.0 23.0 1983 33.8 45.6 20.6 SOURCE: Shopland and Brown, 1985. in the case of cigarettes designed for ultralow yields of tar and nicotine. Certain other components, in particular volatile, toxic components, are released into SS in significantly greater amounts than into MS. Furthermore, ETS contains significantly smaller particles than MS, and nicotine, and perhaps other smoke constituents, is volatilized to a greater extent in SS than in MS. This means that the gas-phase composition of SS differs substantially from that of MS. The health implications to nonsmokers of exposure to ETS may not be a simple extrapolation from the studies of active smokers. The complexities of such extrapolations will be discussed. Children represent a large population of nonsmokers who may be exposed to environmental smoke. Several cohort studies of children are reviewed in Chapter 11. Although there is some variation among these studies, they indicate, mainly through questionnaires, that between 50 and 65 percent of the children have been exposed to tobacco smoke in the home during the past 20 years. Health implications of this exposure for the developing child will be discussed. ORGANIZATION This report begins with a discussion of the components of ETS (Chapter 2) and what in vivo and in vitro studies have determined about ETS (Chapter 3). Various methods of exposure assessment

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Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects are considered in Chapters 4 through 8, including physical effects, questionnaires, and biological markers. Chapters 9 through 15 review epidemiologic studies of possible health effects of these exposures. The health consequences examined range from irritation and allergic reactions to cancer and cardiovascular disease. Only studies that assess exposures under experimental conditions or in the home are included. ETS potentially interacts with constituents of the ambient air. This makes the evaluation of possible health effects due to workplace exposure complex and specific to each situation because of the varying nature of contaminants. Each chapter concludes with a summary of what is currently known, the strength of that knowledge, and what additional information would further clarify the relationship of ETS and possible health effects. Some recommendations for additional research are also given. REFERENCES Griese, V.N. Market growth of reduced tar cigarettes. Recent Adv. Tob. Sci. 10:4–14, 1984. Lee, P.N., Ed. Tobacco Consumption in Various Countries, pp. 82–84. London, England: Tobacco Research Council, 1975. National Research Council, Committee on Airliner Cabin Air Quality. Airliner Cabin Environment: Air Quality and Safety. Washington, D.C.: National Academy Press, 1986. 303 pp. Norman, V. Changes in smoke chemistry of modern day cigarettes. Recent Adv. Tob. Sci. 8:141–177, 1982. Shopland, D.R., and C.Brown. Changes in cigarette smoking prevalence in the U.S.: 1955–1983. Ann. Behav. Med. 7:5–8, 1985. The Tobacco Institute. U.S. tar/nicotine levels dropping. The Tob. Observ. 6:1, 1981. Tobacco Reporter. Cigars in the U.S.: Is the upturn real? Tob. Rep. 111:43–46, 1984. U.S. Department of Agriculture. Tobacco: Outlook and Situation Report. DOA Publ. No. TS-129. Washington, D.C.: U.S. Government Printing Office, 1985. U.S. Department of Commerce. Statistical Abstract of the United States: 1985. Washington, D.C.: U.S. Department of Commerce, Bureau of the Census, 1984. 119 pp.

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