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ABSTRACT: There is only very limited data on the prevalence of contact allergy, as judged by a positive diagnostic patch test, in unselected, non-clinical populations. We carried out a 48 h patch test to 7 common allergens and to the petrolatum vehicle in a total of 2545 adult volunteers in Bangkok. The patch tests were read at 48 h approximately 1 h after patch removal. Positive results were as follows Ni 27.8%, fragrance mix 2.9%, Cr 2.6%, PPD 2.3%, colophony 2.1%, MI/MCI 1.2% and formaldehyde 0.7%. No reactions were found to petrolatum. The particularly high frequency of reactions to Ni was surprising.However, the large female bias (approximately 75:1) strongly suggested that, despite the absence of a 96 h score, that irritancy did not play a significant part in these reactions. Reaction rates to the other 6 contact allergens appeared to confirm predictions made from the extrapolation of diagnostic patch testing or from previous published studies on smaller population groups. The rates of reaction to these allergens also are likely to reflect the extent of exposure in the Bangkok region. Nevertheless, it is interesting to note that over 2% of this adult population appear to be allergic to the cosmetic related allergens PPD and fragrance.
Contact Dermatitis 06/2008; 50(3):128 - 129. · 3.51 Impact Factor
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ABSTRACT: Most studies on the prevalence of allergy to the permanent hair dye chemical para-phenylenediamine (PPD) are reported from populations of eczema patients attending patch-test clinics, and are assumed to be much higher than in the normal population. No data exist on incidence of senitization to PPD resulting from the use of commercial hair dye preparations over a defined time period.
A total of 2545 healthy adult volunteers (Bangkok) were screened for PPD allergy through standard patch testing. Volunteers not allergic to PPD were then recruited into two groups: one group applying a commercial hair dye brand as instructed on a monthly basis for 6 months (n=548) and the other group (controls) (n=516) was instructed not to dye their hair for 6 months. Sensitization to PPD resulting from the use of hair dye over this period was then detected by repeat patch testing.
The prevalence of PPD allergy in a normal adult population was 2.7% (m=2.4%, f=3.2%). Projected to the adult Thai population, at least 1,000,000 Thai individuals could be allergic to PPD. The incidence of sensitization through the monthly application of standard commercial hair dye preparations over a 6-month period was 1.3%, substantially higher than in controls (0.4%), although numbers were small and not statistically significant.
There is a higher prevalence of hair dye allergy among the normal population than previously thought. The incidence of new cases of PPD allergy would indicate that current regulations and practice of hair dye exposure lead to PPD sensitization and allergy, which is a public health problem.
Clinical & Experimental Allergy 01/2008; 37(12):1848-53. · 5.03 Impact Factor
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ABSTRACT: p-Phenylenediamine (PPD) is a commonly used hair-dye and a potent skin allergen. The mechanism of sensitization is unknown, as PPD is protein unreactive. We studied Bandrowski's base (BB), a PPD trimer, as well as 1,4-benzoquinone (BQ), a PPD hapten. PPD patch-test positive patients were patch-tested to BB and BQ. All tests were negative to 0.01% BQ and 0.01% BB. Five of 14 (35.7%) tested had true positive reactions to 0.1% BQ. One percent BQ was found to be irritant. Seven of 43 tested (16%) were positive to either 0.1% or 1% BB. The positive reactions to BB were weak, even when PPD reactions were strong. Mice lymph node assay gave EC3 values of 0.14% for PPD compared with 0.03% for BB. Therefore, BB is approximately 10 times more potent than PPD, taking into account the molarity. We suggest that while PPD may act as a prohapten, there is probably a spectrum of antigenic determinants in vivo. BB may be bound or metabolized by keratinocytes before it reacts with Langerhans cells.
Clinical & Experimental Allergy 11/2006; 36(10):1289-93. · 5.03 Impact Factor
