Clearing the Smoke Assessing the Science Base for Tobacco Harm Reduction (2001) / Chapter Skim
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14 Nonneoplastic Respiratory Diseases
14 Nonneoplastic Respiratory Diseases
Pages 500-542
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From page 500... ...
Because low levels of tobacco toxicants from ETS come in direct contact with the lung, it is necessary to consider the health effects of both mainstream and secondary smoke. In evaluating harm reduction strategies for tobacco-related lung diseases, three major nonneoplastic respiratory diseases linked to cigarette smoking must be considered: COPD, asthma, and respiratory infections.
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From page 501... ...
parlance in considering harm reduction strategies is the contribution of ETS to asthma and respiratory infections in children. Abatement strategies for susceptible children exposed to environmental tobacco smoke may differ from those used to reduce harm in tobacco smokers.
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From page 502... ...
The processes involved, such as inflammation and increased levels of oxidants, are not unique to tobacco-related respiratory diseases. Identifying unique biomarkers is further confounded by the heterogeneous nature of these diseases, the complex mixture that makes up tobacco smoke, and the range of individual susceptibilities to the harmful effects of tobacco smoke among users (see Chapter 11~.
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From page 503... ...
Clearly, the greatest obstacle for developing a specific biomarker is the lack of fundamental information on mechanisms by which exposure to tobacco smoke causes specific respiratory diseases. Insight into understanding the molecular basis of diseases may come from unraveling the complex interactions between genetic makeup and the environment that could evolve from the Human Genome Project or similar molecular studies.
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, showing that smoking cessation may prolong onset of symptoms. SOURCE: Reprinted with permission from Piquette, et al., 2000.
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, including the contribution of tobacco smoke (Witschi et al., 1997) (see Chapter 10~.
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, this type of physiological testing was not predictive of the rate of development of clinically significant airway obstruction, probably because of the heterogeneous nature of COPD (Habib et al., 1987~. Mucous hypersecretion and infections have been postulated to play roles in the accelerated decline of pulmonary function in COPD.
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From page 507... ...
Tobacco smoke also contains oxygen free radicals that, together with products released from inflammatory cells, inactivate protease inhibitors such as oc~-AT. SOURCE: Reprinted with permission from Senior and Shapiro, 1998.
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Mainstream Smoke Exposure The predominant risk factor for COPD is cigarette smoking, and it is estimated to account for 80-90% of the risk of developing COPD (U.S.
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Epidemiological studies have investigated the association between environmental tobacco smoke, respiratory diseases, and reduction in pulmonary function tests (Sherman, 1991; Tredaniel et al., 1994~. It is controversial whether ETS exposure is
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From page 510... ...
An additional report published after Coultas' review concluded that environmental tobacco smoke in adults is associated with small defects in lung function (Carey et al., 1999~. Children Exposure to passive smoking in childhood has been associated with reduced rate of growth of the lung as determined by change of ventilatory function with age in children exposed to environmental smoke compared to unexposed children (Berkey et al., 1986; Tager et al., 1979, 1983, 1987)
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From page 511... ...
between exposure to environmental tobacco smoke and the development of respiratory symptoms. Additional studies are needed, particularly of latency and dose-response relationships, to establish a causal relationship between passive smoking and COPD.
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From page 512... ...
These results were interpreted as showing a benefit from stopping or reducing cigarette smoking. The limitations of this study are that it was not designed to show a change in mortality and morbidity for people who reduced smoking, that estimates are based only on survivors, and that it is a cross-sectional population study.
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From page 513... ...
DHHS, 1989~. Data are available from CPS-I that illustrate the relationship between cigarettes smoked per day and mortality rates from COPD among white male and female current smokers.
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From page 514... ...
Only prospective studies of mortality in smokers who reduce their exposure to cigarettes will provide definitive answers to the question of how much mortality rates are decreased by reducing smoking. Interventional Studies A landmark study in smoking cessation in people at risk for developing symptomatic COPD is the Lung Health Study (Anthonisen et al., 1994~.
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From page 515... ...
Within eight weeks of smoking cessation, lung function had returned to normal in all subjects, suggesting that structural changes in the peripheral airways are reversible in these subjects after cessation of smoking. There is a dearth of information on whether reducing cigarette smoking results in improvement in lung function.
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From page 516... ...
Effect of Short-Term Smoking Reduction on Lung Inflammation The beneficial effect of short-term smoking reduction has been studied in current smokers using a technique that enables inflammation in the lower respiratory tract to be examined directly (ECLIPSE, 2000; Rennard,
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From page 517... ...
who had no clinical or physiological evidence of COPD were enrolled. During the reduced smoking period, cigarette smoke exposure was monitored by exhaled carbon monoxide (CO)
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In summary, asymptomatic smokers clearly have inflammation in their lower respiratory tract, and this inflammation is likely to be involved in the pathogenesis of COPD. The major conclusion of Rennard's (Rennard, 2000; ECLIPSE, 2000)
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From page 519... ...
For example, cigarette smoking stimulates production of cysteinyl leukotrienes (Fauler and Frolich, 1997) , a class of mediators that is increased in asthmatics, causes rapid proliferation of cells in small air
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From page 520... ...
Since the 1960s, it has been suggested that airways hyperresponsiveness and atopy are risk factors for the development of COPD, the socalled Dutch hypothesis (Orie et al., 1961~. Data from several longitudinal studies now clearly show that airways hyperreactivity is a susceptibility factor for accelerated decline of lung function in active cigarette smokers compared to smokers without airways hyperreactivity (Frew et al., 1992; O'Connor et al., 1995; Rijcken et al., 1995; Tashkin et al., 1996; Tracey et al., 1995~.
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From page 521... ...
Environmental Tobacco Smoke Exposure Adults The three major reviews of the health effects of passive smoking published between 1986 and 1992 cited no literature directly examining the association between passive smoking and asthma in adults (NRC, 1986; U.S.
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DHHS,1986~. Most of the studies support the notion that small but significant differences can be detected in respiratory symptom prevalence and pulmonary function studies comparing children exposed to environmental tobacco smoke and children who are unexposed.
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An important issue in evaluating potential strategies for reducing harm from environmental cigarette smoke among asthmatic children in smoking households is to assess the relationship between biomarkers of cigarette smoke exposure and severity of asthma. If a dose-effect relationship exits, these data might indicate the approximate extent of reduction in exposure that may be expected to reduce the severity of asthma in children residing with smokers.
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From page 525... ...
Therefore, there is uncertainty about whether a dose-response relationship exists between cigarette smoke exposure as measured by cotinine levels and severity of asthma, and this subject requires more study before harm reduction studies can be planned. Review of Harm Reduction Strategies Applied to Asthma Several studies have examined the effect of reducing tobacco smoke exposure on wheezing symptoms.
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From page 526... ...
The number of deaths in the United States in 1990-1994 due to respiratory infections that were attributed to cigarette smoking was estimated to be 8,000 per year (Table 14-2~. Pneumonia and influenza are particularly important in the elderly, and the death rate reaches 20% in community-acquired pneumonia (Feldman, 1999; Fine et al., 1996~.
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From page 527... ...
Mainstream Smoke Exposure Cigarette smoking is associated with increased susceptibility to certain types of respiratory infections (Aronson et al., 1982; Finklea et al., 1969; Fischer et al., 1997; Haynes et al., 1966; Imrey et al., 1996; Kark et al., 1982; Nuorti et al., 2000; Parnell et al., 1966; Peters and Ferris, 1967; Stanwell-Smith et al., 1994; Straus et al., 1996~. The dose-response rela
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From page 528... ...
The risk of active tuberculosis was increased by exposure to environmental tobacco smoke. The significance of the association remained after controlling for social and economic status, age, and gender, but it became not significant in those exposed only to passive smoking.
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From page 529... ...
A second series of studies analyzed the association between hospital admissions for lower respiratory tract infections and parental smoking. Diagnoses included undifferentiated chest illness, bronchitis and/or pneumonia, wheezing illness, and bronchiolitis with or without confirmation of respiratory syncytial virus.
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From page 530... ...
These results suggest that impaired host defenses are reversible after smoking cessation. Review of Harm Reduction Strategies Applied to Respiratory Infections One controlled intervention study has examined the effect of acute lower respiratory tract infection after an intervention designed to modify postnatal exposure to tobacco smoke (Greenberg et al., 1994~.
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From page 531... ...
DHHS, 1989~. Subtle effects of tobacco smoke exposure on the lung can be detected by sampling fluid in the lower respiratory tract via a bronchoscope inserted into the airways, but the significance of these changes to clinically important pulmonary disease has not been established.
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RESEARCH AGENDA This section outlines a suggested research agenda for studying harm reduction due to cigarette smoking in respiratory diseases (i.e., COPD, asthma, respiratory infections)
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1982. Association between cigarette smoking and acute respiratory tract illness in young adults.
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1999. The effects of environmental tobacco smoke exposure on lung function in a longitudinal study of British adults.
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1993. Association between exposure to environmental tobacco smoke and exacerbations of asthma in children.
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2000. Maternal smoking during pregnancy, environmental tobacco smoke exposure and childhood lung function.
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1999. Effects of randomized assignment to a smoking cessation intervention and changes in smoking habits on respiratory symptoms in smokers with early chronic obstructive pulmonary disease: the Lung Health Study.
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1986. Environmental Tobacco Smoke: Measuring Exposures and Assessing Health Effects.
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1990. Short-term smoking reduction is associated with reduction in measures of lower respiratory tract inflammation in heavy smokers.
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1995. Do lower respiratory tract infections in early childhood cause chronic obstructive pulmonary disease?
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1994. Exposure to environmental tobacco smoke and risk of lung cancer: the epidemiological evidence.
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1999. Environmental tobacco smoke exposure and asthma in adults.
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