diphenylthiourea and Dermatitis--Contact

In predicting human skin sensitization due to possible risky chemicals, it is not sufficient to evaluate solely the minimum induction dose (MID) or the standard challenge dose (SCD) in the Guinea Pig Maximization Test (GPMT). Nakamura et al. (1994) (Nakamura, A., Momma, J., Sekiguchi, H., Noda, T., Yamano, T., Kaniwa, M., Kojima, S., Tsuda, M., Kurokawa, Y., 1994. A new protocol and criteria for quantitative determination of sensitization potencies of chemicals by guinea pig maximization test. Contact Dermatitis 31, 72-85) previously measured the residual dose of chemicals in the products implicated in human allergic accidents, and stated that '... the level of chemical in the products (direct exposure-dose = DED) was similar to or higher than value of sensitization potency.' However, several of the chemicals listed in their article, show an even lower value of sensitization potency than the DED, although a potential correlation between results of the GPMT and the DED was seemed to be evident; a key question about the essential rule of those parameters therefore remains open. Using the data of Nakamura et al. (1994), we analyzed the functional rules of the three independent parameters, the MID, the SCD, and the DED on which the GPMT is based. Calculations of the degree of allergic reactions elicited in humans provided a range of discrimination constants (D) using the formula; D = DED/(MID*SCD). Possible human allergic accidents may be predicted when the dose of a candidate chemical in a chemical product (equal to DED) exceeds the value; D*(MID*SCD), following the correct evaluation of the MID as well as the SCD.

Topics: Allergens; Animals; Dermatitis, Contact; Dose-Response Relationship, Drug; Drug Hypersensitivity; Guinea Pigs; Household Products; No-Observed-Adverse-Effect Level; Phenylenediamines; Skin; Thiourea; Toxicity Tests

Topics: Adult; Dermatitis, Contact; Female; Humans; Male; Patch Tests; Thiourea

Topics: Animals; Dermatitis, Contact; Guinea Pigs; Isothiocyanates; Skin Tests; Thiocyanates; Thiourea

28 patients reacting to a PVC adhesive tape used in routine patch testing gave positive reactions to diphenylthiourea (DPTU) and to phenylisothiocyanate (PITC) in low concentrations. DPTU is a heat stabilizer in the PVC and is partly decomposed to PITC. The two substances were found in another type of PVC. Thioureas giving isothiocyanates are also used in certain types of rubber. Isothiocyanates are present in plants, mainly of the Cruciferae family, and are also formed from thiuram sulfides and thiocarbamates. The connection between isothiocyanates derived from different sources should be investigated.

Topics: Adhesives; Dermatitis, Contact; Female; Humans; Isothiocyanates; Male; Patch Tests; Polyvinyl Chloride; Thiocyanates; Thiourea