The influence of growing up on a farm on adult allergy, asthma and lung function

Aim : Investigate the impact of early-life farm exposure on objective measures of adult sensitization, asthma and lung function. Background : Early life farming exposure may protect against asthma and allergies, but no study has investigated this effect on measures of lung function. Methods : The ECRHS II recorded living environment (farm, rural environment, inner city) in the first 5 years of life for ∼10,000 26-54 year old participants from 14 countries. Outcomes assessed were: bronchial hyperreactivity (BHR, a fall of >= 20% in FEV1 after methacholine challenge test), current asthma (BHR + wheezing or use of asthma medications in past 12 months), and sensitization. Regression techniques investigated the associations between all outcomes and early childhood environment for any 9farming effect9. Results : Compared to those who grew up in a city, a significantly lower odds of sensitization was observed in those who grew up in a farm (aOR 0.46 95% CI 0.37-0.58) and rural environment (aOR 0.83 95% CI 0.73-0 .94). However, the protective effect for those who grew up on a farm was significantly higher than for a rural environment, which was consistent across all participating countries. Early-life on a farm was also associated with less asthma, BHR and rhinitis, but only in the presence of atopy. Also, women with early-life farm exposure had significantly increased FEV1, independent of both atopy and asthma. Conclusions : The protective effect of farming on asthma, BHR, and rhinitis are driven by atopy. However, farming seems to have an independent beneficial effect on FEV1 among females, which is a novel finding. The protective 9farm-effect9 appears to be stronger than the protective 9rural effect9.