Urinary cotinine and exposure to parental smoking in a population of children with asthma

Background: Studies of the effects of tobacco smoke often rely on reported exposure to cigarette smoke, a measure that is subject to bias. We describe here the relationship between parental smoking exposure as assessed by uri nary cotinine excretion and lung function in children with asthma. Methods: We studied 90 children 4-14 years of age, who reported a confirmed diagnosis or symptoms of asthma. In each child, we assessed baseline pulmo nary function (spirometry) ai td bronchial responsiveness Po carbachol stim ulation. Urinary cotinine was measured by HPLC with ultraviolet detection. Results: Urinary cotinine concentrations in the children were significantly correlated (P <0.001) with the number of cigarettes the parents, especiall y the mothers, smoked. Bronchial responsiveness to carbachol (but not spiro metry test results) was correlated (P <0.03) with urinary cotinine in the c hildren. Conclusion: Passive smoke exposure increases the bronchial responsiveness t o carbachol in asthmatic children. (C) 1999 American Association for Clinic al Chemistry.