Isolated colophony allergens as screening substances for contact allergy.

Rosin has a complex chemical composition. The aim of this study was to investigate if it is possible to define 1 or 2 compounds as the rosin allergens. 2 compounds, 13, 14(beta)-epoxyabietic acid and 7-oxodehydroabietic acid, identified in gum rosin and tall oil rosin, were used as screening substances for patch testing in addition to the standard series. The rosin patch detected more cases of contact allergy than the isolated allergens did. Our suggestion is to patch test with a preparation of gum rosin, as well-defined as possible, for screening. The content of oxidation products should be kept at a constant and rather high level, since these are the main allergens. A rosin series for additional testing of patients with allergic contact dermatits suspected to be caused by rosin could be a valuable tool. Gum rosin and tall oil rosin from different countries should be included, since the amounts of allergens in rosin varies due to source and mode of production. Testing with identified allergens from modified rosin products and with modified rosins could also be performed.