Contact allergy and cross reactivity to substituted thiourea compounds

HPLC analysis of alkyl thioureas in an orthopaedic brace and patch testing with pure ethylbutylthiourea

Ethylbutylthiourea (EBTU) is an accelerator used in the production of chloroprene (neoprene) rubber. EBTU occurs in a mixture with diethylthiourea (DETU) and dibutylthiourea (DBTU) in the accelerator. An analytical method originally developed for analysis of zinc dithiocarbamates in rubber has been used to analyse EBTU, DETU and DBTU in a knee brace responsible for an allergic contact dermatitis in a gardener suffering from arthrosis. EBTU was isolated and gave positive reactions when tested as a pure compound. The test reaction was accompanied by positive reactions to DETU and DBTU.

Occupational allergic contact dermatitis caused by thiourea compounds

Thiourea compounds are mainly used as accelerators in the rubber industry, but also in other industries, e.g., as antioxidants in the graphics industry. Thiourea compounds may provoke allergic contact dermatitis, although the number of reported cases is relatively low. During 1985-1991, we had 5 patients with allergic patch test reactions caused by thiourea compounds. 1 of our patients had to use a knee brace after an occupational accident. He developed allergic contact dermatitis caused by the knee brace, probably because he had become sensitized to diethylthiourea. 2 patients were probably sensitized by diphenylthiourea in neoprene gloves. A florist had an allergic patch test reaction to diphenylthiourea and might have been sensitized by fungicides or pesticides, which break down into thioureas. It is often difficult, however, to detect the source of thiourea compound sensitization. If the patient has contact dermatitis and has been exposed to products that may contain thiourea compounds (or compounds that break down into thiourea compounds), such as rubber, PVC plastic or adhesive, diazo paper, paints or glue remover, anticorrosive agents, fungicides or pesticides, patch testing with a series of thiourea compounds needs to be performed. If patch testing with thiourea compounds is not performed, allergic contact dermatitis caused by thiourea compounds is not likely to be diagnosed.

Contact and photocontact sensitivity problems associated with thiourea and its derivatives: a review of the literature and case reports

Thiourea and its derivatives have been widely used in industry since the beginning of this century, but it was only in the late 1960s that reports of cases of contact dermatitis to these compounds began to appear in the literature. This literature is reviewed. We have observed eight cases of diphenylthiourea sensitivity in patients sensitive to adhesive tape. Four cases are presented of sensitivity to thiourea compounds in diazo-sensitized paper. Three of these patients were contact allergic to dimethylthiourea, and the other was contact and photocontact allergic to thiourea. These skin problems were mainly induced by airborne contact.

Allergic contact dermatitis from ethylene thiourea

A case of allergic contact dermatitis to the rubber additive material ethylene thiourea (ETU) is presented. Testing for cross-sensitivity gave a positive reaction to the fungicide Maneb, manganous ethylenebisdithiocarbamate, but this reaction was probably due to ETU which was detected in Maneb by thin-layer chromatography. Different sources of ETU are reported.