Cutaneous sensitivity to benzidine.

Among 4600 patients tested in 5 years (1973--77), 5.02% of them (231 cases) presented positivity to Benzidine. Of them 16.4% (38 cases) showed concomitant sensitization to one or more allergens of the tested substances of p-amino compounds group. Among the patients who suffered from clinically diagnosed occupational contact dermatitis and showed a positive reaction to Benzidine, 66% of them showed positive reactions to Benzidine as a unique patch-test positivity, whereas 34% of them reacted to Benzidine and to other allergens as well. The occupations where a sensitization to other allergens as well. The occupations were a sensitization to Benzidine was found in a relatively high number were: mechanical industry, house-wives, construction workers, textile industry, hairdressers, and chemical industry. Histological studies of the patch-tests confirm the allergic nature of the reaction. The sources of eventual sensitization and the significance of the circumstantial positivities to this allergen are discussed.