1-3-dibutyl-2-thiourea and Dermatitis--Allergic-Contact

Contact allergy to chloroprene rubber products is well known. Thiourea compounds are considered the cause of allergy. Diethylthiourea commonly occurs in this type of product and can decompose to the sensitizer ethyl isothiocyanate.. To investigate the clinical importance of degradation products and metabolites from organic thioureas in contact allergy to chloroprene rubber with a focus on isothiocyanates and isocyanates.. Patients with contact allergy to diphenylthiourea were patch tested with phenyl isothiocyanate and phenyl isocyanate. Patients with known contact allergy to diethylthiourea were retested with diethylthiourea, while chemical analyses of their chloroprene rubber products were performed. The stability of diethylthiourea, diphenylthiourea and dibutylthiourea in patch-test preparations was investigated. Liquid chromatography/mass spectrometry and solid-phase microextraction/gas chromatography were used for determination of organic thioureas and isothiocyanates.. All patients allergic to diphenylthiourea reacted to phenyl isothiocyanate, two of eight reacted to phenyl isocyanate and six of eight reacted to diphenylthiourea. Four patients allergic to diethylthiourea reacted at retest; diethylthiourea was detected in all chloroprene rubber samples, with levels of 2-1200 nmol cm. Thiourea compounds are degraded to isothiocyanates, which are generally strong or extreme sensitizers, thus acting as prehaptens. This process occurs in both chloroprene rubber products and patch-test preparations. Positive reactions to phenyl isocyanate indicate cutaneous metabolism, as the only known source of exposure to phenyl isocyanate is through bioactivation of diphenylthiourea.

Topics: Adult; Chloroprene; Dermatitis, Allergic Contact; Female; Haptens; Humans; Isocyanates; Isothiocyanates; Male; Middle Aged; Patch Tests; Rubber; Thiourea

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.. 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.. 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).. 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.. 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.

Topics: Allergens; Dermatitis, Allergic Contact; Humans; Isothiocyanates; Local Lymph Node Assay; Neoprene; Thiourea

Thiourea derivatives in rubber products may induce contact sensitization and allergic contact dermatitis. Sensitization is most often from neoprene rubber, but the multitude of possible sensitizing products has remained poorly characterized.. The aim of this study was to collect information on the occurrence of thiourea-related contact allergy and to show novel sources of sensitization.. A mixture of dibutyl-, diethyl-, and diphenylthiourea was included in patch test baseline series in five Finnish dermatology clinics during 2002-2007. In addition, an extended series of rubber chemicals was tested in patients with suspected rubber allergy. Sources of sensitization to thioureas were analysed in sensitized patients.. Thiourea mix yielded positive patch test reactions in 59 of 15,100 patients (0.39%); 33/59 patients were also tested with individual rubber chemicals. Diethylthiourea was positive in 24/33, diphenylthiourea in 5, and dibutylthiourea in 1 patient. The most common sources of sensitization included various neoprene-containing orthopaedic braces, sports equipment, and foot wear.. The sources of sensitization to thiourea chemicals were detected in most cases. These sources comprise a heterogenous group of products extending from orthopaedic materials to sports equipment.

Topics: Adolescent; Adult; Aged; Braces; Dermatitis, Allergic Contact; Female; Finland; Humans; Latex Hypersensitivity; Male; Middle Aged; Patch Tests; Rubber; Shoes; Sports Equipment; Thiourea; Young Adult

Topics: Adult; Allergens; Dermatitis, Allergic Contact; Diagnosis, Differential; Diving; Female; Humans; Patch Tests; Thiourea

Topics: Adolescent; Adult; Air Pollutants; Dermatitis, Allergic Contact; Dermatitis, Occupational; Female; Humans; Male; Occupational Exposure; Skin Tests; Thiourea

Topics: Adult; Dermatitis, Allergic Contact; Female; Humans; Occupational Exposure; Patch Tests; Plastics; Telephone; Thiourea