Contact allergy to colophony and hand eczema. A follow-up study of patients with previously diagnosed contact allergy to colophony.

Colophony is commonly used in many products that we are exposed to both at work and during leisure. At our Department, about 5% of patch tested dermatitis patients show positive reactions to colophony. 83 patients in whom contact allergy to colophony had been diagnosed were followed up after 9-13 years. They were interviewed, examined and retested. At least 30% had current hand eczema on follow-up examination. Among those in whom the dermatitis had started on the hands, there were proportionally more individuals with current hand eczema than among those in whom the onset had been on other parts of the body. 72% of the participants were still patch-test-positive to colophony, and more than 1/2 had additional positive reactions to other allergens. Some of these additional reactions were new compared to the previous test occasion. The degree of exposure to colophony throughout the years was difficult to estimate. Contact allergy to colophony was considered occupational in individuals with, e.g., soldering jobs.