p-Cresol: cause of ink-induced hair depigmentation in mice

p-Cresol has been identified as the active chemical in a laundry-ink responsible for the previously reported contact depigmentation of hair in agouti CBA/J mice. p-Cresol has been shown to induce depigmentation of both skin and hair in agouti as well as black mice. In the agouti mice there were bands and whorls, as well as plaques of white hair. However, the most striking finding was an occult hair depigmentation wherein the new hair shafts were white except for the tips. Such pigment-loss was not apparent on surface examination of the fur, becoming evident only on parting the hairs. All of these patterned hair pigment losses have been related to a unique sensitivity of the follicular melanocytes to the toxic effect of p-cresol during the earliest days of new hair formation, that is, during the initial anagen phase.