Background: Hair dyes are known to contain potent contact allergens for which sensitization rates have increased over the last decade.
Objective: To examine the type and frequency of potent contact sensitizers labelled on hair dyes sold in metropolitan Bangkok, Thailand.
Methods: During the 2013-2014 study period, labelled ingredient information from home use and professional hair dye products was collected.
Results: Two hundred and fifty-two hair dye products were evaluated. One hundred and forty-nine products from 48 brands were domestically produced in Thailand, and 103 products were from 23 multinational brands produced in countries other than Thailand. Two hundred and fourteen of 252 (84.9%) hair dye products were found to contain strong skin sensitizers, with 118 (46.8%) being found in domestically produced products, and 96 (38.1%) being found in multinational brand products. Thirty-eight hair dye products (15.1%) were free of potent skin sensitizers. The number of domestically produced products (31, 20.8%) that were free of potent skin sensitizers was significantly higher (p = 0.002) than the number of multinational brand products (7, 6.8%).
Conclusions: p-Phenylenediamine was the most prevalent potent sensitizer found among domestically produced hair dyes available on the market. Our findings indicate regional differences in hair dye allergen exposure.
Keywords: contact allergens; hair colouring; hair dye; p-phenylenediamine; sensitizer.
© 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.