Allergy to colophony acquired backstage

The masseur of a famous ballet company developed severe contact dermatitis of his hands. Skin testing yielded a surprising result: not one of the suspected 23 different massage creams that the members of the ballet made him use gave a positive reaction. Only colophony, which was included in the standard test series, was positive. Colophony is regularly used on the shoes of dancers on wooden stages to prevent slipping. The masseur had to change his place of employment.