Frequency and relevance of positive patch tests to cyclohexylthiophthalimide, a new rubber allergen

Cyclohexylthiophtalimide (CTP) is currently the most widely used vulcanizat ion retarder in the rubber industry. Little is known about sensitization to CTP, although positive tests to it do occur in patients exposed to rubber objects. A retrospective study of 350 patients who were patch tested with t he standard rubber chemical series was conducted in two departments of derm atology, one in Nancy, France, and one in Leuven, Belgium. Sixteen (4.6%) o ut of the 350 patients had clear and 6 (1.7%) had doubtful positive reactio ns to CTR Cross-sensitivity with other molecules could not be determined. T he source of sensitization in most cases seems to have been protective rubb er gloves at work. In the other cases, sensitization was suspected to have been caused by rubber shoes, elastic bands in underwear, or other rubber ob jects. The determination of the relevance of positive tests remains difficu lt, especially since little is known about the components of rubber product s.