Occupational irritants and asthma: an Estonian cross-sectional study of 34,000 adults.

Occupational exposures make important contributions to asthma morbidity. The role of low/moderate level irritant exposures remains unclear. We aimed to determine which occupational exposures are associated with asthma in an eastern European country with low asthma prevalence. The Estonian Genome Center of University of Tartu collected data from 50 077 adults in 2002-2011. Asthma was assessed through a questionnaire regarding diagnosed diseases, current health status and medication. Exposures to 22 agents during the current and longest held jobs were estimated using an asthma-specific job-exposure matrix. Analyses included 34 015 subjects (aged 18-65 years, 67.0% females), of which 1209 (3.6%) reported asthma (608 with physician-confirmed diagnosis). After adjusting for age, sex and smoking habits, lifetime occupational exposure to known asthmagens (20.4%) was significantly associated with physician-diagnosed asthma (OR 1.28, 95% CI 1.03-1.59), especially high molecular weight agents (flour: OR 2.36, 95% CI 1.31-4.27; animals: OR 1.62, 95% CI 1.00-2.60). Exposure to low/moderate levels of irritants (17.4%) was associated with physician-diagnosed asthma (OR 1.88, 95% CI 1.48-2.37). More pronounced associations were observed in subjects reporting current treated asthma. Beyond confirming the effect of known asthmagens (which are well-known, mostly from observations in western countries), the results provide evidence for a role of low/moderate exposure to irritants. This finding, observed in a country with a low prevalence of asthma and atopy, provides new insight into the understanding of asthma heterogeneity.