Problems in diagnosing occupational allergy to flour: results of allergologic screening in apprentice bakers

Baker's respiratory allergy is reported as one of the most common forms of occupational allergy in many countries. At the first stage of a three-year study of risk factors of occupational allergy we investigated the symptoms reported, and the results of skin prick tests (SPT) to common and flour allergens in 461 current apprentice bakers from three different regions of Poland before starting occupational exposure. The occurrence of cough was reported by 14 subjects (3%), dyspnoea by 4 (0.87%), rhinitis by 18 (3.9%), conjunctivitis by 12 (2.6%) and skin symptoms by 12 subjects (2.6%). Generally, 48 subjects (10.41%) reported at least one symptom, which might suggest the existence of allergic disease. Positive SPT to at least one allergen was found in 99 subjects (21.5%), including 82 subjects (17.78%) with positive SPT to common allergens, 13 subjects (2.81%) to flour allergens and 4 subjects (0.88%) sensitised only to Dermatophagoides farinae. The statistical analysis revealed significant correlation between positive SPT to common allergens and reported rhinitis and conjunctivitis, and between positive SPT to occupational allergens and reported dyspnoea. Moreover, a significant correlation between positive SPT to D. pteronyssinus and D. farinae was found. In our opinion, the results of SPT should be very carefully examined, when diagnosing occupational allergy, as in some apprentice bakers positive results of SPT to flour allergens are found before vocational training. In all apprentice bakers, SPT to common and occupational allergens should be performed before starting occupational exposure. It would ensure the exclusion of subjects already sensitised to occupational allergens. Positive SPT to Dermatophagoides farinae has a very limited value in recognising baker's allergy.