Soup Kettle Topics: Epidemiology-Airborne/Environmental Issues

Title: Maternal Smoking During Pregnancy, Environmental Tobacco Smoke Exposure and Childhood Lung Function
Author: Gilliland, F. D.; Berhane, K.; McConnell, R.; Gauderman, W. J.; Vora, H.; Rappaport, E. B.; Avol, E.; Peters, J. M.; (Date: Apr, 2000)
Journal: Thorax; V. 55; Issue: 4; Pages: 271-6

Abstract: BACKGROUND: Exposure to environmental tobacco smoke (ETS) during childhood and in utero exposure to maternal smoking are associated with adverse effects on lung growth and development. METHODS: A study was undertaken of the associations between maternal smoking during pregnancy, exposure to ETS, and pulmonary function in 3357 school children residing in 12 Southern California communities. Current and past exposure to household ETS and exposure to maternal smoking in utero were assessed by a self-administered questionnaire completed by parents of 4th, 7th, and 10th grade students in 1993. Standard linear regression techniques were used to estimate the effects of in utero and ETS exposure on lung function, adjusting for age, sex, race, Hispanic ethnicity, height, weight, asthma, personal smoking, and selected household characteristics. RESULTS: In utero exposure to maternal smoking was associated with reduced peak expiratory flow rate (PEFR) (-3.0%, 95% CI -4.4 to -1.4), mean mid expiratory flow (MMEF) (-4.6%, 95% CI -7.0 to -2.3), and forced expiratory flow (FEF(75)) (-6.2%, 95% CI -9.1 to -3.1), but not forced expiratory volume in one second (FEV(1)). Adjusting for household ETS exposure did not substantially change these estimates. The reductions in flows associated with in utero exposure did not significantly vary with sex, race, grade, income, parental education, or personal smoking. Exposure to two or more current household smokers was associated with reduced MMEF (-4.1%, 95% CI -7.6 to -0. 4) and FEF(75) (-4.4%, 95% CI -9.0 to 0.4). Current or past maternal smoking was associated with reductions in PEFR and MMEF; however, after adjustment for in utero exposure, deficits in MMEF and FEF(75) associated with all measurements of ETS were substantially reduced and were not statistically significant. CONCLUSIONS: In utero exposure to maternal smoking is independently associated with decreased lung function in children of school age, especially for small airway flows.
Notes: Journal Article
Author Address: Department of Preventive Medicine, University of Southern California School of Medicine, Los Angeles, California 90033, USA.

Title: Home Dampness, Current Allergic Diseases, and Respiratory Infections among Young Adults
Author: Kilpelainen, M.; Terho, E. O.; Helenius, H.; Koskenvuo, M.; (Date: Jun, 2001)
Journal: Thorax; V. 56; Issue: 6; Pages: 462-7

Abstract: BACKGROUND: The relation between home dampness and respiratory symptoms among adults is well confirmed, but data on specific allergic diseases and respiratory infections is more limited. Individual factors that may enhance susceptibility to the effects of home dampness are mainly unknown. METHODS: The association between home dampness and current physician diagnosed asthma, allergic rhinitis, allergic conjunctivitis, atopic dermatitis, common colds, and bacterial respiratory infections was studied in a questionnaire survey of 10 667 Finnish first year university students aged 18-25 years. The dampness categories analysed were visible mould and visible mould or damp stains or water damage during the last year. In multivariate analyses adjustment was made for parental education, active and passive smoking, type and place of residence, pets, and wall to wall carpets. The interaction effect of atopic heredity and dampness was investigated. RESULTS: Visible mould or damp stains or water damage was reported by 15.0% of the respondents. In multivariate models there was a positive association between home dampness and current asthma, allergic rhinitis, and atopic dermatitis, as well as common colds > or =4 times per year and other respiratory infections, but not between home dampness and allergic conjunctivitis. The strongest association was found between exposure to visible mould and asthma (OR 2.21, 95% CI 1.48 to 3.28) and common colds (OR 1.49, 95% CI 1.18 to 1.87). The risk of current asthma in damp homes was highest among subjects with atopic heredity. CONCLUSIONS: The risk of current asthma, allergic rhinitis, and atopic dermatitis was higher in damp homes. Of the respiratory infections, the risk of common colds was most clearly increased.
Notes: Journal Article
Author Address: Department of Pulmonary Diseases and Clinical Allergology, University of Turku, Turku, Finland.

Title: Consequences of Long-Term Inflammation. The Natural History of Asthma
Author: Sears, M. R.; (Date: Jun, 2000)
Journal: Clin Chest Med; V. 21; Issue: 2; Pages: 315-29

Abstract: Although asthma is classically defined as reversible airflow obstruction, and often remits in younger subjects with milder disease, the natural history of asthma is that various degrees of airflow obstruction may persist and, in the long-term, asthma may become moderately to fully irreversible. Severe, irreversible airflow obstruction may develop despite apparently appropriate therapy and in the absence of other risk factors, such as smoking and environmental insults. All studies of subjects with persisting asthma show increased decline in lung function compared with normal subjects. Persistent abnormal physiology is reflected both in reduced airflow rates and in increased airway responsiveness. The cellular and molecular mechanisms of airway remodeling are described elsewhere in this issue. Questions not yet clearly answered are the reasons for these persistent abnormalities in some asthmatics, and which subjects are most at risk. Factors that adversely impact the outcome as adults identified relatively consistently among many longitudinal studies of the natural history of asthma include: Female gender. Environmental tobacco smoke exposure in childhood. Personal tobacco smoking in adolescence and adulthood. Age of onset of symptoms. Severity of childhood asthma. Duration of asthma. Severity of lung function abnormality in childhood. Bronchodilator reversibility. Degree of airway hyperresponsiveness. Delay in initiating anti-inflammatory therapy. Remission among adult asthmatics is uncommon, but is associated with better initial lung function, young age, male gender, and lesser degrees of airway responsiveness. The role of atopy remains controversial. Conversely, risk factors for death from asthma include older age, smoking, atopy, impaired lung function, and moderate to high reversibility. Treatment can improve lung function, reduce airway responsiveness, and improve quality of life. The overall effect of treatment on the natural history of the disease is not yet clear, despite significant short-term improvements from effective anti-inflammatory therapy.
Notes: Journal Article
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Author Address: Department of Medicine, McMaster University, Hamilton, Ontario, Canada.

Title: Influence of Parental Smoking on Respiratory Symptoms During the First Decade of Life: The Tucson Children’s Respiratory Study
Author: Stein, R. T.; Holberg, C. J.; Sherrill, D.; Wright, A. L.; Morgan, W. J.; Taussig, L.; Martinez, F. D.; (Date: Jun 1, 1999)
Journal: Am J Epidemiol; V. 149; Issue: 11; Pages: 1030-7

Abstract: Compelling evidence suggests a causal relation between exposure to parental cigarette smoking and respiratory symptoms during childhood. Still, the roles of prenatal versus postnatal parental smoking need clarification. In this study, the authors assessed the effects of passive smoking on respiratory symptoms in a cohort of over 1,000 children born during 1980-1984. The children were enrolled in the Tucson Children’s Respiratory Study in Tucson, Arizona, and were followed from birth to age 11 years. The population was generally middle class and consisted of two main ethnic groups, non-Hispanic Whites (75%) and Hispanics (20%), reflecting Tucson’s population. Information on parental smoking and on wheeze and cough in their children was elicited from parents by using questionnaires at five different surveys. Data were analyzed both cross-sectionally and by using the generalized estimation equation approach, a longitudinal mixed-effects model. The best-fitting model indicated that maternal prenatal but not postnatal smoking was associated with current wheeze (odds ratio = 2.3, 95% confidence interval 1.4-3.8) independently of a family history of asthma, socioeconomic factors, and birth weight. This effect was time dependent and significant only below age 3 years; although independent of gender, the association was stronger for girls (odds ratio = 3.6, 95% confidence interval 1.6-8.0). Cough was not associated with parental smoking during the first decade of life. This transitory effect of maternal prenatal smoking on wheezing could be due to changes that affect the early stages of lung development.
Notes: Journal Article
Author Address: Department of Pediatrics, College of Medicine, Pontificia Universidade Catolica RS, Porto Alegre, Brazil.

Title: Adult-Onset Asthma Is Associated with Self-Reported Mold or Environmental Tobacco Smoke Exposures in the Home
Author: Thorn, J.; Brisman, J.; Toren, K.; (Date: Apr, 2001)
Journal: Allergy; V. 56; Issue: 4; Pages: 287-92

Abstract: BACKGROUND: In recent years, we have gained better knowledge about the influence of indoor environments on respiratory symptoms and asthma. The purpose of this study was to examine certain exposures in the home environment and the risk of adult-onset asthma. METHODS: A nested case-referent study of adult-onset asthma was performed in a random population sample (n = 15813), aged 20-50 years. Cases for the study included subjects reporting “physician-diagnosed” asthma (n= 174). The referents (n = 870) were randomly selected from the whole population sample. The case-referent sample was investigated with a comprehensive mailed questionnaire about exposures in the home environment, asthma, respiratory symptoms, smoking habits, and atopy. Odds ratios (OR) with 95% confidence intervals (CI) were calculated while controlling for age, sex, smoking, and atopy. RESULTS: Increased adjusted OR for asthma were associated with exposure to molds (OR 2.2, 95%, CI 1.4-3.5), environmental tobacco smoke (OR 2.4, 95%, CI 1.4-4.1), and the presence of a wood stove (OR 1.7, 95% CI 1.2-2.5). CONCLUSIONS: This population-based case-referent study indicates that self-reported domestic exposures to molds or environmental tobacco smoke can be associated with adult-onset asthma.
Notes: Journal Article
Author Address: Department of Environmental Medicine, Goteborg University, Sweden.

Title: Parental Factors Affecting Respiratory Function During the First Year of Life
Author: Young, S.; Sherrill, D. L.; Arnott, J.; Diepeveen, D.; LeSouef, P. N.; Landau, L. I.; (Date: May, 2000)
Journal: Pediatr Pulmonol; V. 29; Issue: 5; Pages: 331-40

Abstract: In a prospective, longitudinal, population-based cohort study of familial and environmental influences on the development of wheezing respiratory illness in early childhood, we identified infant length, weight, gender, and exposure to maternal cigarette smoking as significant determinants of lung function during the first year of life. A cohort of 237 infants (106 females: 131 males) was evaluated, and 496 lung function measurements were made between the ages of 1-12 months. Respiratory function was assessed using the rapid thoracic compression technique to obtain maximum expiratory flow at functional residual capacity (V’maxFRC). Parental history of asthma and smoking habits during pregnancy were obtained by questionnaire. Data were analyzed using a longitudinal random effects model. Infants with a parental history of asthma and/or in utero passive smoke exposure were compared to a reference group of infants who had no parental history of asthma and in whom neither parent smoked pre- or postnatally. Boys were found to have a consistently lower V’maxFRC (-21.05 mL.s(-1)) throughout the first year of life in comparison to girls (P < 0.05). Maternal smoking during pregnancy was associated with a lower V’maxFRC in both genders in comparison to unexposed infants (P < 0.05). V’maxFRC was unaffected by parental history of asthma. Gender-specific normative equations for V’maxFRC throughout the first year of life were derived for the infant cohort as a whole and also for subgroups of infants, based on parental asthma and smoking history. We conclude that lung function during the first year of life differs between genders and is adversely affected by in utero passive tobacco smoke exposure. Gender-specific predictive equations for V’maxFRC should be used during infancy.
Notes: Journal Article
Author Address: Department of Respiratory Medicine, Princess Margaret Hospital for Children, Perth, Western Australia, Australia.

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