Reduced risk of atopic sensitization among farmers: The Humboldt Study

Background: It needs to be clarified whether farming is associated with a reduced risk of atopy or allergic condition. There is a lack of consistent evidence for prevalences of atopy, respiratory allergy and asthma in adult farmers. Methods: A cross-sectional study of adults ( n = 2,081) was conducted in the town of Humboldt, Sask. Allergy skin prick tests were conducted to determine atopic sensitization. Respiratory allergy and physician- diagnosed asthma were based on self-reporting. Logistic regression was used to assess the associations of atopy, respiratory allergy and asthma with farming practices, adjusting for other important variables. Results: Of 2,081 participants, 27.8% were farmers. Reduced risks of atopic sensitization, respiratory allergy and asthma were observed among farmers compared to nonfarmers. After adjustment for sex and age, which are major confounders, the odds ratio for atopic sensitization was 0.79 ( 95% confidence interval: 0.65, 0.97) for farmers versus nonfarmers. Asthma showed a similar trend; however, there was no statistically significant difference in either respiratory allergy or asthma rates observed between farmers and nonfarmers. Conclusions: The prevalence of atopy was lower in adult farmers than in non- farmers. Copyright (C) 2007 S. Karger AG, Basel