<p>Paraphenylenediamine (p-phenylenediamine, PPD) is a colourless/slightly pink, grey or yellow crystalline solid (lumps or powder). On oxidation, usually through exposure to air, it turns red, brown then finally black. PPD is essentially a dye and chemical intermediate. It is used as a hair dye and in hair and skin dyeing formulations. In industry, its uses include the manufacture of azo-dyes and dye-stuff intermediates, including fur dyeing formulations. It has also been administered orally as a pain killer (Averbukh et al 1989), and as a cure for constipation (Shemesh et al 1995), resulting in severe sequelae.</p>