An Induction phase is performed for 3 weeks, where 9 consecutive patches are applied to the same skin site on the arms or back for 24 h, three times a week. Each induction site is evaluated for erythema and oedema after removal of the patch. Two weeks after the last induction, a challenge patch is applied for 24 h and subsequently read at 48h and 96h. The response after challenge is compared to the responses reported after the early induction patches. The induction patch responses are also noted and interpreted as evidence of cumulative irritation.