para-Phenylenediamine Containing Hair Dye: An Overview of Mutagenicity, Carcinogenicity and Toxicity

The great demand for hair dyes can be seen by the proliferation of hair salons.Their ability to impart temporary or permanent colour change to the hair satisfies the desire of consumers for beauty, fashion, and a look-younger image.para-Phenylenediamine (PPD) is found in more than 1000 hair dye formulations and is the most frequently used permanent hair dye component in Europe, North America, and East Asia.In addition, PPD containing permanent hair dyes account for three-quarters of global use and more than one-third of women use in Europe, North America, and East Asia.However, PPD has been banned in Germany, France and Sweden in the early 1900's as a hair dye component and the hazard of PPD on health has been discussed for the past few decades.PPD containing hair dyes have been associated with cancer and mutagenicity, with supportive evidences from both clinical and laboratory studies.Apart from that, PPD has potential toxicity which includes acute toxicity such as allergic contact dermatitis and subacute toxicity.In this article, we provide comprehensive review on the chemical ingredients of hair dyes, roles of PPD in hair dye, metabolic mechanisms of PPD through in vivo and in vitro studies, and mechanism involvement in the health effect of PPD as evidenced from both clinical and laboratory studies.