ALLERGIC CONTACT-DERMATITIS FROM THE PRESERVATIVE 1,2-BENZISOTHIAZOLIN-3-ONE (1,2-BIT PROXEL(R)) - A CASE-REPORT, ITS PREVALENCE IN THOSE OCCUPATIONALLY AT RISK AND IN THE GENERAL DERMATOLOGICAL POPULATION, AND ITS RELATIONSHIP TO ALLERGY TO ITS ANALOG KATHON(R) CG

Occupational contact allergy to 1,2-benzisothiazolin-3-one (1,2-BIT, Proxel(R)) is analysed. This compound is widely used in industry as a preservative in water-based solutions such as pastes, paints and cutting oils. The optimal concentration for patch testing proved to be 0.4 g/l (0.04%) in water. In 4 out of 17 patients (23%) at occupational risk (painters, paper-hangers), contact allergy to 1,2-BIT was found. Of 556 consecutive dermatological patients without clear occupational risk, 10 (1.8%) showed positive patch tests to 1,2-BIT; in 3 patients 1,2-BIT contact allergy was related to domestic paper-hanging. Although the chemical structure of 1,2-BIT shows some analogy with the preservative Kathon(R) CG, true cross-sensitivity was found to be unlikely.