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Data on occupational contact urticaria (protein contact dermatitis included) in Finland during 1990-1994 were analyzed. Altogether 815 cases were reported to the Finnish Register of Occupational Diseases during this period, compared with 1944 cases of occupational allergic contact dermatitis. Accordingly, the total number of occupational allergic contact dermatoses was 2759, 29.5% being contact urticaria and 70.5% being allergic contact dermatitis. Occupational contact urticaria was much more common in women (70%) than in men (30%). The 6 most common causes of contact urticaria were (1) cow dander (362 cases = 44.4%), (2) natural rubber latex (193 cases = 23.7%), (3) flour, grains and feed (92 cases = 11.3%), (4) handling of foodstuffs (25 cases = 3.1%), (5) industrial enzymes (14 cases = 1.7%) and (6) decorative plants (13 cases = 1.6%). The occupations with the highest numbers of occupational contact urticaria were farmers (341 cases), domestic animal attendants (61), bakers (53), nurses (42), chefs (40) and dental assistants (28). The ranking list of the most common occupations with occupational contact urticaria per 100,000 employed workers was as follows: (1) bakers (140.5 cases per 100,000 employed persons), (2) preparers of processed food, (3) dental assistants, (4) veterinary surgeons, (5) domestic animal attendants, (6) farmers and silviculturalists, (7) chefs, cooks and cold buffet managers, (8) dairy workers, (9) horticultural supervisors, (10) laboratory technicians and radiographers, (11) physicians, (12) butchers and sausage makers, (13) laboratory assistants, (14) dentists and (15) nurses (21.2 cases per 100,000 employed person). Low-molecular-weight chemicals caused very few cases of occupational contact urticaria, the most common being 2-ethylhexyl acrylate (5 cases). To summarize, occupational contact urticaria forms a large group of occupational contact dermatoses, and dermatologists need to be able to diagnose IgE-mediated immediate skin allergic diseases.

Background: Cow dander is the most common cause of occupational contact urticaria in Finland. Occasionally cow dander also causes allergic contact dermatitis, which can be revealed by patch testing with cow dander. Objective: A patient with a combined type I and type IV allergy to cow dander is the subject of this report. Results: She had intense pruritus, whealing, and severe dermatitis, but no respiratory symptoms. Skin test and radioallergosorbent test indicated that she had both type I and type IV allergy to cow dander. Conclusion: Increasing numbers of cases with both type I and type IV allergy are reported, but the mechanism is not clear. In our clinic, we classify immediate reactions as contact urticaria if the clinical picture involves whealing, and as protein contact dermatitis if dermatitis dominates the clinical picture. If delayed allergic patch test results are obtained, we consider it allergic contact dermatitis.