Original article Respiratory allergy in apprentice bakers: do occupational allergies follow the allergic march? Baker’s respiratory allergy is reported to be a major form of occupational allergy in many countries (1–4). Cross-sectional studies of bakers have shown the prevalence of allergic rhinitis ranging from 14 to 39% and that of asthma from 4.9 to 10% (3, 5–8). On the other hand, it was estimated that only about one-third of bakers with work-related symptoms are sensitized to occupational allergens (1). It remains of interest whether this may be due to nonallergic mechanisms or to methodological shortcomings of the cross-sectional studies (9). However, this observation was also con- firmed by follow-up studies, e.g. Gautrin et al. reported that only three out of 30 apprentices with work-related symptoms of rhinoconjunctivitis had been sensitized to flour (10). Although a number of studies have been performed on subjects exposed to high-molecular-weight (HMW) aller- gens (1, 3, 4, 8), the prospective studies in this population are much less common, especially those performed on bakers who were not exposed to flour prior to observa- tion. Only Gautrin et al. and De Zotti and Bovenzi conducted studies on apprentice workers under exposure to high-molecular-weight allergens (11, 12). To our knowledge, none of the studies employed a specific challenge test that is the gold standard in the diagnosis of occupational respiratory allergy. The aim of the present project was to evaluate the incidence, risk factors and natural course of occupational respiratory allergy in apprentice bakers. The baseline for our observation was the onset of vocational training. Background: This prospective study describes the incidence, risk factors and natural history of occupational respiratory allergy in apprentice bakers. Methods: Two hundred and eighty-seven apprentice bakers were examined using a questionnaire, skin prick tests (SPTs) to common and occupational allergens, evaluation of total serum IgE level and specific anti-flour and a-amylase IgE, before, 1 year and 2 years after the onset of vocational training. To diagnose occupational respiratory disease, spirometry, histamine and aller- gen-specific inhalation challenge tests were performed. Results: The incidence of work-related chest symptoms was 4.2% in the first year and 8.6% in the second year of exposure. Hypersensitivity to occupational allergens developed in 4.6 and 8.2% of subjects, respectively. The incidence of occupational allergic rhinitis was 8.4% after 1 year and 12.5% after 2 years, and that of occupational asthma/cough-variant asthma 6.1 and 8.7%, respectively. The latency period of work-related rhinitis symptoms was 11.6 ± 7.1 months and chest symptoms 12.9 ± 5.5 months. Only in 20% of occupational asth- matics could allergic rhinitis be diagnosed a stage earlier. In 21 out of 25 subjects with occupational asthma, chronic cough was the sole clinical manifestation of the disease. Stepwise logistic regression analysis revealed that positive SPT to common allergens was a significant risk factor of hypersensitivity to occupa- tional allergens (OR ¼ 10.6, 95% CI 5.27; 21.45), occupational rhinitis (OR ¼ 3.9, 95% CI 1.71; 9.14) and occupational asthma (OR ¼ 7.4, 95% CI 3.01; 18.04). Moreover, positive SPT to occupational allergens on entry to the training was a significant risk factor of asthma (OR ¼ 6.9, 95% CI 0.93; 51.38). Conclusions: The incidence of occupational asthma and rhinitis in apprentice bakers is high and increases z with the duration of exposure. Skin reactivity to common and occupational allergens is the main risk factor of bakersÕ asthma. Most cases of work-related respiratory symptoms among apprentice bakers are related to a specific sensitization. In most subjects who developed occupational asthma, rhinitis occurred at the same time as the chest symptoms did. J. Walusiak 1 , W. Hanke 2 , P. Górski 3 , C. Pałczyn ´ski 1 1 Department of Occupational Diseases & Occupational and Environmental Allergy Centre; 2 Department of Environmental Epidemiology, Nofer Institute of Occupational Medicine, Lodz; 3 Department of Pulmonology and Allergology, Medical University of Lodz, Poland Key words: apprentices; asthma; bakers' incidence; natural history; risk factors. Jolanta Walusiak, MD, PhD Department of Occupational Diseases Nofer Institute of Occupational Medicine 8 Teresy St. 90-950 Lodz Poland Accepted for publication 10 September 2003 Allergy 2004: 59: 442–450 Printed in UK. All rights reserved Copyright Ó Blackwell Munksgaard 2004 ALLERGY 442