Environmental Tobacco Smoke Measuring Exposures and Assessing Health Effects (1986) / Chapter Skim
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11 Effects of Exposure to Environmental Tobacco Smoke on Lung Function and Respiratory Symptoms
11 Effects of Exposure to Environmental Tobacco Smoke on Lung Function and Respiratory Symptoms
Pages 182-222
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From page 182... ...
In some smokers, the rate of decline of FEVER is rapid, leading to clinically important chronic airflow obstruction. The structural changes associated with active cigarette smoking are seen in both the conducting airways and the pulmonary parenchyma (for a more detailed description, see U.S.
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From page 183... ...
Cessation of smoking leads to a rapid decrease in respiratory symptoms, an improvement in lung function, and a shift towards the nonsmoker's rate of decline of FEVER (U.S. Public Health Service, 1979, 1984~.
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From page 184... ...
1971, 1975, 1978~. PLAUSIBILITY FOR AN EFFECT DUE TO PASSIVE SMOKING The dose of cigarette smoke delivered to the lungs of nonsmokers exposed to ETS is both qualitatively and quantitatively different from mainstream smoke, being a small fraction of that delivered to the lungs of an active smoker (see discussions in Chad ter 7~.
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From page 185... ...
If individuals who are most susceptible to the irritating effects of cigarette smoke on the lower respiratory tract do not start to smoke or, having started, soon quit as smokers, then a population of nonsmokers would be more likely to include the most susceptible individuals than a population of smokers. The existence of different subpopulations introduces an additional complication to the extrapolation from high-dose exposure in active smokers to the low-dose exposures of nonsmokers.
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From page 186... ...
Children who have parents who smoke are themselves more likely to smoke. Therefore, because active smoking is likely to have a considerably greater impact on respiratory symptoms and lung function than exposure to ETS, rn~scIassification of the children who smoke will tend to overestimate the effect of exposure to ETS.
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From page 187... ...
187 TABLE 11-1 Potentially Confounding and Effect Modifying Factors in Epidemiologic Studies of Exposure to Environmental Tobacco Smoke Unreported active smoking Tobacco products Marijuana Clove cigarettes Developmental factors Maternal smoking during pregnancy Factors related to outdoor environment Outdoor temperature, humidity Respirable and nonrespirable particulates, e.g., fugitive dust Pollens and other allergens Factors related to indoor environment Crowding Number and age of siblings Total number of people/animals in dwelling unit Total number of smokers in dwelling unit Household conditions Frequency of air exchanges Temperature and humidity Use and condition of air conditioning units Conditions of child care facilities Unvented combustion products from heating/cooking stoves Respirable and nonrespirable particulates, e.g., wood smokes Pollens, molds, mites Allergens and infectious organisms Formaldehyde Factors related to work/hobbies Work/hobby-related exposure to gases, fumes, particulates Miscellaneous factors Annoyance response to tobacco smoking Reporting biases Assessing Respiratory Variables Methods commonly used to assess the effect of passive smoking on the respiratory system, such an respiratory symptom questionnaires and measurement of lung function, may lead to some error. The problems associated with the respiratory symptom questionnaires include: ~ Different questionnaires are used in studies.
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From page 188... ...
CROSS-SECTIONAL STUDIES In the following sections, selected cross-sectional studies of respiratory symptoms, lung function, and respiratory infections and longitudinal studies of lung functions are reviewed. The studies reviewed here are larger studies in which attempts have been made to standardize assessments and many of the data-gather~ng techniques, including interviews.
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From page 189... ...
. Three problems are especially important for studies of respiratory symptoms In children, i.e., underreported active smoking on the part of children, recall bias leading to overreport~ng of symptoms by parents, and the confounding variables of infections in parents.
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From page 190... ...
Children whose parents had a positive history had 72-155% higher symptom and illness rates than children whose parents had no history of these illnesses. Adjustment for parental respiratory history reduced the size of the estimated effects of maternal smoking on respiratory symptoms and illnesses by 20 to 30%0, but the associations remained statistically significant for most of the outcome symptom and respiratory illness variables (odds ratios of 1.23 and 1.2B, respectively)
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From page 191... ...
191 of I:: ._ V, ._ Ct o ._ C)
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From page 193... ...
furthermore, there appears to be a doseresponse relationship between exposure and the likelihood of the child's developing respiratory symptoms or a respiratory illness. TO the Harvard Study, a significant dose-response relationship was reported; the more mothers who smoked, the greater the risk of respiratory symptoms and illnesses among their children.
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From page 194... ...
to measure Jung function in young children and also hard to dissect out the relative contribution of ETS and that of natural variation and the effect of respiratory infections to pulmonary damage. A majority of the studies (reviewed in Table 11-3)
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From page 195... ...
195 oc ~: ._ ;> - o ;> v, ._ ct o ._ u, u' o 5 a, c, V2 · ~ o ._ c~ s~ c.
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From page 197... ...
However, the effect may be important in two respects. First, the existence of statistically significant differences related to parental smoking leads to the conclusion that there are pathophysiologic effects of exposure to ETS in the lungs of the growing child.
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From page 198... ...
(1984~. may be at an increased risk for the development of chronic airflow obstruction in adult life.
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From page 199... ...
No information was given on possible childhood exposures to cigarette smoke of the women studied. Kentner and coworkers (1984)
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From page 200... ...
Respiratory symptoms, by themselves, may have little clinical significance but would be important if associated with a change in the rate of lung growth and development or the development of pulmonary pathology at older ages. There is evidence from two cohort studies (Table 11-4)
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From page 202... ...
Another aspect that deserves more attention in future studies Is the effect on children's pulmonary function when parents stop smoking. T11 ~ EFFECT OF PASSIVE SMOKING ON RESPIRATORY INFECTIONS There is now strong evidence that bronchitis, pneumonia, and other lower-resp~ratory-tract illnesses occur more frequently (at least during the first year of life)
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From page 203... ...
In this group of children, the incidence of pneumonia and bronchitis in the first year of life was associated with the parents' smoking habits. This was true whether or not the parent has respiratory symptoms.
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From page 204... ...
204 cat o u' Is: .
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From page 207... ...
During the second year, the relationship between maternal smoking and lower respiratory illness was equivocal. The relationship disappeared by the third year.
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From page 208... ...
arising because children living in homes of smokers are at risk of such diseases for other reasons. Some of the studies have examined the possibility that the association is indirect by allowing for confounding factors such as social class, parental respiratory illnesses and birthweight and have concluded that such factors do not explain the results.
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From page 209... ...
The mechanism for this increase is less certain. It could represent a direct effect of ETS on the respiratory tract of the infant or it could be due to such infants' being exposed to more parental respiratory infections as a result of their parents' smoking.
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From page 210... ...
210 Cal ._ Cal C)
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From page 211... ...
~ this regard, there is already some Information relating early childhood respiratory illness to subsequent respiratory symptoms and impaired lung function later in childhood (WooIcock et al., 1984; McConnochie, 19853. Evidence is also accumulating that respiratory infections in early childhood are related to an accelerated decline of FEW in adult life (Burrows et al., 1977b; Lebow~tz and Burrow, 1976~.
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From page 212... ...
The differences were small and were considered by the investigators to be of questionable importance. Subjective complaints were common ~ this and other acute cigarette smoke exposure studies, particularly eye irritation and~cough.
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From page 213... ...
One subject complained of wheezing and chest tightness, although his pulmonary function wan not significantly Trip aired. Subjective symptom scores were higher overall for the higher smoke exposure (13.8 versus 10.3 pot/subject at the lower exposure)
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From page 214... ...
It was concluded that asthmatics did not have unusual measurable responsiveness to ETS exposure in this study. The findings of Dahms et al.
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From page 215... ...
None of the studies could be performed blind to the presence of ETS. Therefore, the authors could not exclude the possibility that pulmonary function changes could be emotionally related to cigarette smoke exposure, especially ~ those patients who reported previous histories of adverse response to ETS exposure.
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From page 216... ...
Children of parents who smoke compared with the children of parents who do not smoke show increased prevalences of respiratory symptoms, usually cough, sputum, and wheezing. The odds ratios from the larger studies, adjusted for the presence of parental symptoms, were I.2 to I.8, depending on the symptoms.
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From page 217... ...
What Scientific Information Is Missing I ETS exposure during childhood may Influence the development of airway hyperresponsiveness in adult life.
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From page 218... ...
Higgins. Passive smoking, respiratory symptoms and pulmonary function: A longitudinal study in children.
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From page 219... ...
Colley, J.R.T. Respiratory symptoms in children and parental smoking and phlegm production.
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From page 220... ...
Ferris, Jr. Respiratory symptoms and lung function in women with passive and active smoking.
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From page 221... ...
Spengler. Respiratory disease rater and pulmonary function in children associated with NO2 exposure.
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From page 222... ...
Pilsner. Persistent wheeze: Its relation to respiratory illness, cigarette smoking, and level of pulmonary function in a population sample of children.
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