Factors associated with p-phenylenediamine sensitization: data from the Information Network of Departments of Dermatology, 2008-2013.

Background. Risk factors for p-phenylenediamine (PPD) sensitization include the use of hair dyes, the application of temporary black henna tattoos, working as a hairdresser, and, possibly, exposure to hair dye pretests. Objectives. To quantify the impact of these (putative) risk factors on PPD sensitization. Methods. Six items related to PPD exposure were added to the routine Information Network of Departments of Dermatology questionnaire from 2008 to 2013. A retrospective analysis of data from 4314 patients tested with PPD 1% pet. was conducted. Results. Of the PPD-positive patients (n= 271), 80% had their hair dyed, and, of these, 57% subsequently developed scalp dermatitis, whereas only 11% had had a henna tattoo. The self-administrated pretest with hair dye was performed by only a few patients, precluding a more detailed analysis. Hair dyeing [odds ratio (OR) 6.0; 95% confidence interval (CI): 3.9-9.4], henna tattoos (OR 2.4; 95% CI: 1.5-3.7) and being a hairdresser (OR 2.1; 95% CI: 1.3-3.2) increased the risk of PPD sensitization. Neither dyeing of own hair nor application of a temporary henna tattoo seemed to affect PPD sensitization in hairdressers. p-Aminoaryl compounds more often gave positive reactions in patients with henna tattoo. Conclusions. Hair dyeing is the major risk factor for PPD sensitization in this clinical setting, and application of a temporary black henna tattoomay also lead to (strong) PPD sensitization.