Human maximization testing of D&C Yellow no. 10 and Yellow no. 11.

By the maximization test, using 0.5% D&C Yellow no. 11 in pet., 15 of 20 human volunteers became contact sensitized. All reacted to a challenge concentration of 1000 ppm and one down to 1 ppm. The high allergenic potential of this dyestuff was confirmed. There were no cross reactions to purified samples of D&C Yellow no. 10. In contrast, 5% solutions of pure D&C Yellow no. 10 failed to sensitize human subjects. Cross reactions to this substance in persons sensitized to D&C Yellow no. 11 are due to impurities.