Tobacco Documents Online

CHILDHOOD RESPIRATORY D~SEASE Perhaps no claim regarding ETS is as capable of provoking strong feelings as the charge that parents who smoke may harm the health of their children. While the issue of parental smoking is laden with emotion, the scientific basis for the claim is difficulZ to interpret. For example, while one study examines respiratory symptoms or illness such as coughs and colds by questionnaire responses from parentsI, another measures lung function with special equipment at a school or health facility.~ In the U.S. alone, according to one report, this has led to a situation in which studies of ETS and the respiratory system are "being carried out by at least three different groups, are employing different populations and methodologies and have led to varying conclusions.''3 Perhaps not surprisingly, such studies, each with a different sample size, data collection method, and analysis, tend to yield factually incompatible and contrary conclusions. For instance, although certain studies have reported adverse findings between parental smoking and respiratory illness in children,~'4z or invasive bacterial or viral infections~s'~9 others have observed no significant reiationship.1'5°-66 After a five-year study of over 400 children, for example, a Dutch research group concluded there was "no evidence" that parental smoking had an appreciable effect on respiratory symptoms in school children.~z A similar conclusion was

reached by a group of U.S. researchers, including a critic of smoking, who found "no siqnificant relation" between parental s~oking and respiratory symptoms in ~ study of nearly 400 families with 816 children in three cities.5° The contradictory nature of findings on the issue of

confounding factors. The potential impact of such factors was given special consideration in the report from a workshop on ~TS sponsored by the U.S. National Instikutes of Health.~ After listing numerous such factors, including types of heating used, socio-economic status and demographic and medical characteristics of the study population, the report cautioned "that any study which ignores them will be seriously flawed." The importance of such factors in evaluating the outcome of research on parental smoking is supported by a number of reports which have shown that the use of gas stoves in the home may be independently associated with respiratory disease~°'5~,~9,9~-9~ and impaired pulmonary performance9z'98 in children. One group of British researchers acknowledged the possible influence of factors such as cross-infection in the home and genetic susceptibility to childhood respiratory illness and symptoms.~'~ More recently, researchers in Hong Kong reported "a highly significant correlation" between the frequency of respiratory illnesses of mothers and their children.~ One study reported that children with recurrent respiratory tract infections "tend to belong to £amilies ~ith health problems.''~ Maternal age has also now b~en recognized as a possible f~ctor in childhood lower respiratory illness.TM

Other confounding factors independent of parental smoking have been reported recently in the literature. For example, studies in the United Kingdom have identified damp housin~ and paternal occupation~6 as potential explanatory factors for the occurrence o£ respiratory illness in children. Other recent studies have identified outdoor air pollution,~°z-~1° infections transmitted during day-care attendance~3'I~I°I~ decreased breast- feeding,I~,~5 and the use of kerosene heaters and woodburning stoves in the home and exposure to wood smoke outdoors~6"I~° as factors related to childhood respiratory disease. directly related reactions in some report, moreover, The relevance of dampness in the etiology of respiratory symptoms in children is supported by current research which l~nks dampness with the presence of molds, dust mites, fungi and other allergenic microbes. The growth of fungi and molds in the home is to respiratory symptoms and sensitization individuals.~,~z~'~z~ Recent investigations that sxposure to ETS does not increase sensitization to common allergens in children.~25~2~ Exposure to indoor sources of NO2 has also been associated with respiratory symptoms and decreased pulmonary function in children.~'~s others have conceded that the reliance of such studies on questionnaires for information about respiratory symptoms casts

doubt on their reported findings. In one study that reported a significant association between parental smoking and respiratory symptoms, for example, it was noted that even "slight changes~' in the way the q~/estions were phrased could result "in substantial differences in the type of responses one obtainso''~ similarly, another study Observed that there was a s~gnificant difference in the respiratory symptoms reported depending on which parent completed the questionnaire.~ Authors of another study that reported adverse effects of parental smoking on the respiratory health of children conceded that "since the exposure variables used in these analyses were subject to substantial measurement error, a more refined measurement of personal exposure is required.''~9 One researcher who is critical of parental smoking has stated that "quantitative assessment of involuntary exposure of infants and children to ETS has been very imprecise and probably inaccurate.''129 Studies util±zing seemingly more objective standards such as actual measurements of lung function are also open to criticism. Even reviewers of the literature who are critical of parental smoking concede that the tests used in these studies are "influenced by a large number of variabl~s.''13a They list age, height, and gender of the test su~Dject as well as his or her motivat±on, cooperation, and effort pu~ forth during the test, the skill and experience of the operator, and the type of

instrume~tat±on used as variables that can affect ~he results of pulmonary function measurements. The reviewers explain that these problems are especial.ly important in pulmonary function measures taken in children. In 1989, two American co-researchers, Witorsch and Witorsch, reported that "it has been shown that the mean pulmonary performance within a sinqle group of children can vary significantly from one spirometry test to the next without any apparent cause" and that it "is noteworthy that such statistically significant differences are similar in magnitude to most of the small decrements in pulmonary function reported in children of smoking parents.'~ The shortcomings of studies analyzing the relationship between ETS exposure and childhood health were highlighted in a 1988 report by two U.S. investigators who re-examined 30 such studies and evaluated them for their scientific validity.~z They noted that while several studies of adeq~/ate scientific design had reported a statistically significant relationship between ETS exposures and childhood health, "most studies had significant design problems that prevent reliance on their conclusions." The authors concluded that "many questions remain, and future studies should consider important methodological standards to determine more accurately the effect of passive smoking on child health."

Thus, claims that parental smoking plays a causal role in the development of respiratory symptoms and reduced lung function in children are not scien:ifically justified. Such claims are typically based upon a single study of a selected symptom (such as cough or wheeze). These kinds of studies invariably fail to consider nutrition, health habits of the family,, and other l~festyle variables. Similarly, studies that report reduced lung function in children of smoking parents fail to address the issue of socio-economic status or the potential role of genetic and family traits in pulmonary function capabilities,s5 Moreover, the reductions reported in the literature are small and of uncertain clinical or biological significance, and are contradicted by a number of studies that reportedly have observed no effect of parental smoking on children's lung function. -- AN --

REFE_ R~NCES Camacho, E., Colomer, P.R., and Betoret, J.L.D., "Pulmonary Symptoms and Pulmonary Punctional Tests Among Children ~n Relation to the Area of Residence," European Respiratory Diseases 63(2): 165-166, 1982. Lebowitz, M., Armet, D.B., and Knudson, R., "The Effect of Passive Smoking on Fulmonary Function in Children," Environment IDternationa~ 8: 371-373, 1982. U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health, ,'Report of Workshop on Respiratory Effects of Involuntary Smoke Exposure: Epidemiologic Studies, May 1-3, 1983," December, 1983. committee on Passive Smoking, Board on Environmental Studies and Toxicology, National Research council, Environmental Tobacco Smoke: Measur~nq Exposures and Assessing Mealth Effects. Washington, National Academy Prsss, 1986. U.S. Department of Health and Human Services, Public Health Services, office on Smoking and Health, Th9 Health Consec~/ences qf Involuntary Smoking: A Repprt of the Surqeo~ ~eneral~ DH_HS Publication No. (CDC) 87-8398, 1986. Bland, M., Bewley, B.R., Pollard, V., and Banks, M.H., "Effect of Children's and Parents' Smoking on Respiratory symptoms," Archives of Diseases in Childhood 53(2): 100-102, 1978. Bonham, G., and wilson, R., ',Children's Health in Families with Cigarette smokers," American Journal of Public Hea.$th 71(3): 290-293, !981. Burchfiel, C., Higgins, M.W., Keller, J.B., Howatt, W.F., Butler, W.J., and Higgins, I.T.T., "Passive Smoking in Childhood: Respiratory Conditions and Pulmonary Function in Tecumseh, Michigan," American Review of Respirat°ry Disease 133 (6) : 966-973, 1986. Cameron, P., and Robertson, D., "Effect of Home Envirorument Tobacco Smoke on Family Health," Journal of ADD1 ied Ps choy~hg_~ 57(2) : 142-147, 1973. -- AN --

i0. ii. 13. 14. 15. 16. 17. 18. 19. Chen, Y., "Synerqistic EZfect of Passive Smoking and Artificial Feeding on Hospitalization for Respiratory Illness in Early Childhood," Chest 95: !004-1007, 1989. Colley, 3., "Respiratory Symptoms in Chil'dren and Parental Smoking and Phlegm Production," ~ritish Medical Journal 201-204, 1974. colley, J., Holland, W.W., and Corkhill, R.T., "Influence of Passive 5mokinq and Parental Phleqm on Pneumonia and Bronchitis in Early Childhood," Lancet If: i031-i034, 1974. Dockery, D., Speizer, F.E., Stram, D.O., Ware, J.H., Spengler, J.D., and Ferris, B.G., "Effects of Inhalable Particles on Respiratory Health of Children," Ame.rica.n Review of Respiratory Disease 139: 587-594, 1989. Ekwo, E., weinberger, M.M., Lachenbruch, P.A., and Huntley, W.H., "Relationship of Parental Smoking and Gas Cooking to Respiratory Disease in Children," Chest 84(6): 662-668, 1983. Fergusson, D., Horwood, L.J., Shannon, F.T., and Taylor, B., "Parental Smoking and Lower Respiratory Illness in the First Three Years of LiZe," Journal of Ep.idemio.lo~y and Co~munitv H~ealt~ 35(3): 180-184, 1981. Fergusson, D., and Horwood, L.J., "Parental Smoking and Respiratory Illness During Early Childhood: A Six-year Longitudinal Study," Pediatric Pulmonoloqy 1(2): 99-106, 1985. ?erris, B., Dockery, D.W., Ware, J.H., Speizer, F.E., and Spiro, R., "The Six-City Study: Examples of Problems in Analysis of Data," ~Dviron~en~a.l Health Perspective~ 52: 115-!23, 1983. Gortmaker, S., Walker, D.K., Jacobs, F.H., and Ruch-Ross, H., "Parental Smoking and the Risk of Childhood Asthma," American J~ourna! of...~ubliG Health 72(6): 574-579, 198~. Harlap, S., and Davies, A., "Infant Admissions to Hospital and Maternal Smoking," Lancet I: 529-532, 1974.

20. 23. 24. 25. 27. Kraemer, M., Richardson, M'A., Weiss, N.S., Furukawa, C.T., Shapiro, G.G., Pierson, W.~., and Bierman, C.W., "~isk Factors for Persistent Middle Ear Effusions: Otitis Media, catarrh, Cigarette Smoke Exposure, and Atopy," Journal of the American Medical Associat$on 249(8): 1022-102S, 1983. Murray, A., and Morrison, B., "Passive Smoking and the Seasonal Difference of S~ver±ty of Asthma in Children," Chest 94(4): 701-708, 1988. Neuspiel, D., Rush, D., Butler, N.R., Golding, J., Bijur, P.E., and Kurzon, M., "Parental Smoking and Post-lnfancy Wheezing in Children: A Prospective Cohort S£udy," ~American Journal of Public Health 79(2): 168-171, 1989. Ogston, s., Florey, C.D.V., and Walker, C.H.M., "Association of Infant Alimentary and Respiratory Illness with Parental Smoking and Other Environmental Factors," Journal of E~idemioloq¥ and co,unity Health 41(i) : 21-25, 1987. Schenker, M., Samet, J.M., and Speizer, F.E., "Risk Factors for Childhood Respiratory Disease: The Effect of Host Factors and Home Environmental Exposures," ~American Review o~ Respiratory Diseas~ 128: 1038-1043, 19S3. Somerville, S., Rona, R.J., and Chinn, S., "Passive Smoking and Respiratory Conditions in Primary School Children," Journal of ~pidemiolo~y and Community Health 42~2): I05-i~0, 1988. Strachan, D., Jarvis, M.J., and Feyerabend, C., "Passive Smokinq, Salivary Co~inine Concentrations, and Middle Ear Zffusion in 7 Year Old Children," B~itish Medical ~Qurnal 298: 15~9-1552, 1989. Tsimoyianis, G., Jacobson, M.S., Feldman, J.G., Antonio- Santiago, M.T., Clutario, ~.C., N~ssbaum, M., and Schenker, I.N., "Reduction in Pulmonary Function and Increased Frequency of Cough Associated With Passive Smoking in Teenage Athletes," Pediatrics 80(I): ~2-36, 1987. Ware, J., Dockery, D.W., Spiro, A., Speizer, F.E., and Ferris, B.G., "Passive Smoking, Gas Cooking, and Respiratory ~ealth of Children Living in Six Cities," ~Ameriqan Review of Respiratory Disease 12S: 366-374, 1984.