RESUMO
BACKGROUND: Exposure to chloroprene rubber has resulted in numerous cases of allergic contact dermatitis, attributed to organic thiourea compounds used as vulcanization accelerators. However, thiourea compounds are not considered to be strong haptens. OBJECTIVES: To analyse common commercial chloroprene materials for their contents of diethylthiourea (DETU), dibutylthiourea (DBTU), diphenylthiourea (DPTU), and their degradation products, isothiocyanates; and to investigate the sensitization potencies of possible degradation products of the mentioned thiourea compounds. METHODS: Liquid chromatography/mass spectrometry (MS) was used for quantification of organic thiourea compounds in chloroprene products, such as medical, sports and diving gear; isothiocyanates were measured by solid-phase microextraction/gas chromatography/MS. Sensitization potencies were determined with the murine local lymph node assay (LLNA). RESULTS: DETU was identified at concentrations of 2.7-9.4 µg/cm(2) in all samples, whereas neither DBTU nor DPTU was detected. At 37°C, degradation of DETU in the materials to ethyl isothiocyanate (EITC) was detected. EITC and ethyl isocyanate showed extreme and strong sensitization potencies, respectively, in the LLNA. CONCLUSIONS: DETU can act as a prehapten, being degraded to EITC when subjected to body temperature upon skin contact. EITC could thus be the culprit behind allergic contact dermatitis caused by chloroprene rubber.