Environmental tobacco smoke exposure during the first 10 years of life: A risk factor for allergic and non-allergic airway disorders?

Abstract

Rationale Effect of in utero tobacco ( IUT) and environmental tobacco smoke ( ETS) exposure on the development of allergic sensitization and airway disorders during the first 10 years of life. Methods In a prospective birth cohort (Multicentre Allergy Study [MAS] with n=1314 newborns), outcome and exposure were annually assessed by questionnaire or interview. Additionally to IUT exposure, four ETS exposure categories were compared: 1.never, 2.by father only, 3.irregularly by mother, and 4.regularly by mother +/-father. Four outcomes were considered: allergic sensitization to inhalant allergens (specific IgE >0.35kU/I), allergic rhinitis, wheezing and respiratory infections. Longitudinal effects of ETS exposure were assessed by generalized estimating equation models (adjusted for education, birth weight, breast feeding, number of siblings, and pets). Results ETS exposure increased with age, 18% had been exposed continuously by maternal ETS and 40% of children had never been exposed to parental ETS. Since genetic predisposition is known to be the most important risk factor for atopy we stratified our analysis by atopic family history. In children with atopic parents ( aP), combined IUT and regular maternal ETS exposure significantly increased the risk for allergic sensitization (1 aP: OR=1.8 [95% C.I.: 1.1–3.1]; 2 aP: OR=7.0 [1.8–26.7]) and wheezing (1 aP: OR=2.1 [1.3–3.8]; 2 aP: OR=5.7 [2.0–19]). No effect was found in children without aP and for rhinitis and respiratory infections. Conclusions Longterm passive pre- and postnatal tobacco smoke exposure increases the risk for allergic sensitization or wheezing during the first 10 years of life. This effect, however, was only seen in children with a genetic predisposition to allergy.