Comparison of the sensitivities of the Buehler test and the guinea pig maximization test for predictive testing of contact allergy

International test guidelines, such as the Organisation for Economic Cooper ation and Development (OECD) guideline #406, recommend 2 guinea pig methods for testing of the contact allergenic potential of chemicals: the Guinea P ig Maximization Test (GPMT) and the Buehler test. Previous comparisons betw een the methods suggested that the Buehler test was less sensitive than the GPMT although modified Buehler test protocols were used. Parallel GPMT and Buehler tests were conducted according to OECD guideline #406 using a mult iple-dose design and test results were analysed using a standard logistic d ose-response model. To compare the sensitivity of the 2 test procedures the test conditions were kept identical and the following chemicals with a ran ge of sensitization potentials were tested: chloraniline, chlorhexidine, eu genol, formaldehyde, mercaptobenzothiazole and neomycin sulphate. Formaldeh yde and neomycin sulphate were strong sensitizers in both tests. Mercaptobe nzothiazole, eugenol and chloraniline were all strong sensitizers in the GP MT, eugenol and mercaptobenzothiazole were negative in the Buehler test and equivocal results were obtained with chloraniline, Chlorhexidine was negat ive in the GPMT and equivocal responses were obtained with the Buehler test . Higher induction concentrations were needed to show allergenicity in the Buehler test and for some allergens the Buehler test protocol was not sensi tive enough to demonstrate allergenic potential.