ABSTRACT
AIM: The environmental exposure of farm children to micro-organisms in dust has been related to a reduced prevalence of asthma and atopy. The aim of this study was to evaluate the relation between settled dust endotoxin and development of asthma and/or atopy in rural and urban school children. METHODS: A comparative study was conducted on 40 rural and 40 urban school children (6-12 years). Parental self-reported allergic symptoms questionnaires were distributed. Forced expiratory volume in the first second (FEV1), forced vital capacity (FVC) were measured using MIR spirobank and FVE1% was calculated. Skin prick testing with the most common aeroallergens was performed. Limulus amebocyte lysate endotoxin content was measured in settled dust samples. RESULTS: The rural group which has higher exposure to farm animals and feeding on farm milk has less allergic symptoms. Rural students showed highly significant FEV1, FEV1% and significant FVC versus urban students (110.9±19.7, 103.8±12.2, 105.8±24.3 vs. 92.3±24.2, 98.4±18.9, 92.7±23.2, respectively). Rural school dust contains significantly higher level of endotoxin (2-3 EU/mg) than urban school (0-0.1 EU/mg). Urban residence was associated with increase risk of asthma after age and sex adjustments ([ORadj], 5.16; 95% [CI], 0.95-28). CONCLUSION: Our results support the hygiene theory, i.e., endotoxin exposure could be protective to asthma and atopy in school children.
