Cross-reactions among parabens, para-phenylenediamine, and benzocaine: a retrospective analysis of patch testing.
BACKGROUND
Parabens are alkyl ester derivatives of para-hydroxybenzoic acid and are the most commonly used preservatives in the cosmetic industry. Cross-reactions with para-amino compounds, namely, benzocaine and para-phenylenediamine (PPD), have been reported but are thought to be extremely rare.


OBJECTIVE
To evaluate the rate of cross-reactivity between parabens, PPD, and benzocaine in a population of patients patch-tested in a hospital-based contact dermatitis clinic.


METHODS
A retrospective analysis of 4,368 patients consecutively patch-tested between July 1989 and June 2005.


RESULTS
Our study demonstrated that the rate of cross-reactions to parabens in PPD- and benzocaine-positive patients combined is 2%.


CONCLUSIONS
This cross-reaction rate is significant in the tested population but still falls within the previously reported rates of sensitivity to parabens in the general population (0 to 3.5%).
Turchin
Irina
I
McGill University Health Centre, Royal Victoria Hospital, Montreal, PQ, Canada.
Moreau
Linda
L
Warshaw
Erin
E
Sasseville
Denis
D
D000779:Anesthetics, Local / Q000009:adverse effects*; D001566:Benzocaine / Q000009:adverse effects*; D004396:Coloring Agents / Q000009:adverse effects*; D003429:Cross Reactions; D017449:Dermatitis, Allergic Contact / Q000209:etiology*; D005260:Female; D006801:Humans; D008297:Male; D010226:Parabens / Q000009:adverse effects*; D010328:Patch Tests; D010655:Phenylenediamines / Q000009:adverse effects*; D011310:Preservatives, Pharmaceutical / Q000009:adverse effects*; D012189:Retrospective Studies
D000779:Anesthetics, Local; D004396:Coloring Agents; D010226:Parabens; D010655:Phenylenediamines; D011310:Preservatives, Pharmaceutical; D001566:Benzocaine; C029728:4-phenylenediamine