Wheat allergen exposure and the prevalence of work-related sensitization and allergy in bakery workers

Background: Occupational airway diseases are common among bakers. The present study describes the association between exposure to wheat allergen levels and sensitization to wheat allergens, work-related upper and lower respiratory symptoms and asthma in bakery workers. Methods: As part of a Health Surveillance System for early detection of (allergic) occupational airway diseases a so-called 'validation study' was performed among Dutch bakers for validation of a diagnostic model that predict the likelihood of sensitization to specific workplace allergens. The present study used serology and questionnaire results of a subgroup of 860 bakers participating in the validation study. An earlier developed job-exposure matrix was used to predict average and cumulative personal exposure to wheat allergens. Results: The prevalence of wheat sensitization, work-related respiratory symptoms and asthma increased till average wheat exposure levels of approximately 25-30 mug/m(3), leveled off and decreased at higher exposure concentrations. Exposure-response curves showed a stronger pronounced bell-shape with cumulative exposure. Associations were strongest for asthma and work-related lower respiratory symptoms (PR approximately 2 and PR approximately 3.5-4.5 for average and cumulative exposure, respectively). Associations were only found in atopics. Wheat sensitization was an important factor in the prevalence of respiratory symptoms. Conclusion: In accordance with earlier studies, the present study showed a bell-shaped exposure-response relationship especially for cumulative wheat allergen exposure with sensitization, allergic respiratory symptoms and asthma. The healthy worker effect may be the possible explanation for the bell-shaped relationship.