Exposure to environmental tobacco smoke and sensitisation in children

¹ Institute of Environmental Medicine, KI, Sweden
² Clinical and Allergy Unit, Department of medicine, KI, Sweden
³ Department of Women's and Children's Health, Uppsala University, Sweden

^* To whom correspondence should be addressed. E-mail: eva.lannero{at}ki.se.

Accepted 2 September 2007

	Abstract

Background: Exposure to environmental tobacco smoke increases the risk of respiratory illness in children but data are inconclusive regarding the risk of IgE-sensitisation.

Objective: To elucidate whether exposure to smoking pre- and/or postnatally is related to IgE-sensitisation in children at 4 years of age.

Methods: As part of a prospective birth cohort study (BAMSE) a total of 4,089 families with children answered questionnaires when the child was 2 months, 1, 2 and 4 years on environmental factors and symptoms of allergic disease. Blood collected at age 4 years from 2,614 children was analysed for IgE antibodies to common inhalant and food allergens. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using logistic regression with adjustments for potential confounders.

Results: There was no evident association between maternal smoking during pregnancy and risk of IgE-sensitisation. In contrast, a dose-response effect was found for exposure to environmental tobacco smoke (ETS) from parental smoking during the first few months of life and IgE-sensitisation. There was an increased risk for sensitisation to inhalant and/or food allergens, ORadj= 1.28, (95% CI 1.01 to 1.62), among children exposed to ETS at 2 months of age. The risk appeared particularly elevated for indoor inhalant allergens, such as cat (ORadj 1.96; 95% CI 1.28 to 2.99), and for food allergens (ORadj 1.46; 95% CI 1.11 to 1.93). The IgE sensitising effect of ETS seemed to be confined to infants of parents without allergic diseases and to ETS exposure during early infancy.

Conclusions: Our data indicate that exposure in early infancy to ETS increases the risk of IgE-sensitisation to indoor inhalant and food allergens.

Keywords: Children, ETS, Parental smoking, Prevention, Sensitisation