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Published on: September 16, 2011
The risk of active sensitization to PPD
1Department of Dermatology, University Hospital Nijmegen, The Netherlands. dr.Devos.S@medmail.com
Contact Dermatitis
|April 12, 2001
Summary
Para-phenylenediamine (PPD) patch testing poses a sensitization risk. Simultaneous testing with para-aminoazobenzene increases irrelevant reactions, suggesting active sensitization. PPD should not be in routine series.
Area of Science:
- Dermatology
- Allergology
- Toxicology
Background:
- Para-phenylenediamine (PPD) and para-aminoazobenzene are known strong sensitizers.
- Patch testing is a common diagnostic procedure for identifying allergic contact dermatitis.
- Combined testing of para-compounds may heighten the risk of active sensitization.
Purpose of the Study:
- To evaluate the percentage and relevance of positive patch test reactions to PPD.
- To assess the risk of active sensitization from PPD patch testing.
- To compare PPD patch test relevance when tested alone versus simultaneously with para-aminoazobenzene.
Main Methods:
- Studied patch test reactions to PPD in 2058 patients.
- Conducted simultaneous PPD and para-aminoazobenzene testing in 678 patients.
- Compared early (2-3 days) and late (7 days) reactions for relevance.
Main Results:
- 4.3% of patients reacted to PPD when tested alone; 3.1% when tested with para-aminoazobenzene.
- Relevant reactions were estimated at 21.1% for PPD alone and 39.7% with para-aminoazobenzene.
- Late reactions were consistently deemed irrelevant, indicating potential active sensitization.
Conclusions:
- Sensitization to PPD via patch testing is a significant risk.
- Routine series should exclude PPD due to high irrelevant late reactions suggesting active sensitization.
- PPD can be tested non-routinely for suspected industrial exposure or specific localizations.
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