ALLERGEN SENSITIZATION AND EXPOSURE TO IRRITANTS IN INFANCY

We investigated the relationship between residence in the neighbourhoo d of an aluminium smelter and the prevalence of atopy in schoolchildre n (7-13 years of age). Atopy was assessed in 556 of the 620 participan ts by a skin prick test with eight common aeroallergens. The median ex posures to sulphur dioxide and fluoride during the pollen season in th e age interval 19-36 months were 24 and 3.1 mu g/m(3) in the spring an d 20 and 3.3 mu g/m(3) in the summer, respectively. The odds ratio (OR ) of having atopy was 2.0 (95% CI: 1.2-3.3) in those children who had lived in the index area for 7 years or more compared with those who ha d lived there less than 7 years (cumulative effect). The OR of atopy w as 2.5 (1.4-4.4) in those who had lived in the index area during the a ge interval of 19-36 months compared with rural residence during this age-interval (age-specific effect). When the age-specific Medical Depa rtment effect and the cumulative effect were compared in the same logi stic model, the former decreased to 1.1 (0.4-3.0), whereas the latter was 2.2 (0.7-6.6). The results indicate that exposure to these low lev els of irritants during early childhood increases allergen sensitizati on in children.