Contact Allergen of the Year: p-Phenylenediamine

Vincent A. DeLeo


Dermatitis. 2006;17(2):53-55. 

In This Article

Ethnic Differences

Fisher was the first to suggest that PPD was a more important allergen for black persons than for white individuals.[15] More recently, a study comparing the incidence of reactions to specific allergens between white and black patch-test subjects from the Cleveland Clinic reported that black men had a statistically higher incidence of PPD allergy than white men had.[16] In a larger population studied by the North American Contact Dermatitis Group, of 45 antigens tested over a 6-year period, only PPD was found to cause a higher incidence of positive reactions in black patients than in white patients. In fact, the incidence among the black patients was so high as to make PPD one of the most common allergens in those individuals, rivaling nickel and neomycin in incidence of reaction. The reason for this difference is presently undefined; although it may be a true genetic difference, it is most likely related to patterns of use. It has been suggested that the difference is due to the fact that black persons are likely to use darker shades of dye, which contain higher concentrations of PPD.[17]

In some ethnic groups, facial hair is considered an essential part of religious observance. Hsu reported on eight Arabic men with facial dermatitis found to be due to PPD allergy related to the dyeing of beard hair.[18]

As the population of the United States changes with the increasing diversity of racial and ethnic groups, these differences in reaction patterns will certainly play a greater role in the clinical presentation of PPD allergy.


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