Indoor risk factors for atopic eczema in school children from East Germany

This study aimed to investigate the relation between environmental influences such as arsenic, cadmium, lead, and mercury, as well as environmental tobacco smoke, pet keeping, and heating systems on the prevalence of atopic eczema. Therefore, a multicenter cross-sectional study of school children aged 5-14 years, including a standardized questionnaire, blood and urine analyses, and a dermatological examination, was undertaken. A cases-control approach was chosen in order to identify relevant risk factors. A total of 2200 school children (response 79.1%) of two areas (Bitterfeld, Hettstedt) polluted by industrial activities and an agricultural control region (Zerbst) of the former German Democratic Republic were examined. Atopic eczema as identified by dermatological examination and history was the outcome variable of interest. Body burden of arsenic and heavy metals and questionnaire data on environmental tobacco smoke exposure, pet keeping, and heating system were investigated as potential risk factors. The overall prevalence of atopic eczema was 2.6%, with higher prevalences in the industrial areas (2.5 and 2.9%) compared to the control area (1.6%, not significant). Bivariate analyses did not reveal statistically significant associations between atopic eczema and tobacco smoke exposure or the body burden of arsenic and heavy metals. According to multiple logistic regression analysis, atopic eczema was significantly more frequent in predisposed families and those who reported keeping guinea pigs (OR=4.37, CI 2.15-8.91), but not other pets, like dogs, cats, and hamsters. In comparison to a distant heating system, a decreased risk was observed in households with central heating system (OR=0.30, CI 0.10-0.90), whereas the presence of a gas heater with an exhaust pipe connection to the wall was associated with a significantly elevated risk for eczema (OR=8.22, CI 2.44-27.66). The heating system and exposure to certain animal allergens are related to the manifestation of atopic eczema. Further studies are needed to clarify how far a causal relationship is reflected by these findings.