Exposure to passive smoke in the womb or in childhood linked to asthma development
(2 July 2005: VIDYYA MEDICAL NEWS SERVICE) -- Children's exposure to pre- and post-natal tobacco smoke carries a substantial risk for them to develop asthma and respiratory symptoms as adults, according to study results in the first issue for July 2005 of the American Thoracic Society's (ATS) peer-reviewed American Journal of Respiratory and Critical Care Medicine.
Investigators conducted an 11-year community cohort study on the incidence of asthma and respiratory symptoms among a sample population in western Norway. The study included data from 2,819 respondents to both baseline and follow-up questionnaires. The researchers examined the incidence of asthma and five respiratory symptoms related to self-reported exposure from those surveyed to maternal smoking while in the womb and during childhood. The medical scientists also examined exposure to passive smoking from other household members during the individual's childhood.
The researchers noted that the combined total exposure for the children to environmental tobacco smoke could explain almost one-quarter of the cases of adult asthma.
They said that the estimated attributable fractions suggest that almost a quarter of the incidence cases of adult asthma could be prevented if children were not exposed to pre- and post-natal environmental tobacco smoke. They pointed out that they believed this was the first study to show that pre- and post-natal passive smoking induces a lasting vulnerability to asthma or respiratory symptoms.
The survey was conducted in 1985 and 1996/97 on a random sample of the population of the city of Bergen and 11 surrounding municipalities in western Norway. The first questionnaire to be mailed out contained 40 questions about respiratory health, allergies, smoking habits, and occupational exposure. After two reminder letters, 3,370 subjects responded. A follow-up mailing 11 years later extended the questionnaire to 58 questions, adding queries on education and passive smoking. A total of 2,819 subjects returned the questionnaire in 1996 and 1997, after two written reminders and a phone call.
In addition to their results on passive smoking, the investigators found no statistically significant relationship between the exposures in question and such confounders as the subject's sex, age, educational level, smoking habits, pack years, occupational exposure, and hay fever.
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