Preventing irritant contact dermatitis with protective creams: influence of the application dose.

BACKGROUND

Skin protection creams (PC)s are used in the occupational setting to help prevent irritant hand dermatitis. The actual amounts of PC applied and the resulting dose per unit area on hands at work are lower than recommended.

OBJECTIVES

To assess the influence of the applied dose on the efficacy of PCs in the prevention of irritant contact dermatitis.

METHODS

Experimental cumulative irritant contact dermatitis was induced by twice daily application of 0.5% NaOH or sodium lauryl sulfate (SLS) for 4 days on the backs of 20 healthy volunteers. Test areas were left unprotected or were pretreated with three different PCs applied at a low dose (2 mg/cm(2) ) or a high dose (20 mg/cm(2) ) before irritation. Irritant responses were assessed by visual scoring and measurement of transepidermal water loss, chromametry, and corneometry.

RESULTS

Although cumulative irritant dermatitis developed in all unprotected test sites, irritation was significantly reduced in a dose-dependent manner on PC-protected sites. The higher doses of all PCs provided significant protection against irritation. However, the lower dose of one product did not significantly protect against SLS-induced irritation.

CONCLUSIONS

The protective efficacy of PCs depends on the amount of product applied per unit skin surface area. Some products may show no protective efficacy when used at doses close to those practically applied at workplaces. Future efficacy studies of PCs should be performed with doses not higher than 2 mg/cm(2) , to avoid overestimation of their protective efficacy.