Multicenter evaluation of sunscreen UVA protectiveness with the protection factor test method.

Abstract

Currently there is no consensus on a test method to determine the protectiveness of sunscreens in the UVA region alone. The protection factor in UVA (PFA) test method was evaluated to determine its ability to detect dose-response, specificity for UVA protection only, and repeatability between laboratories, and to detect whether the protection factors depended on the skin response observed (erythema or tanning). Sunscreens containing 0%, 2%, or 5% oxybenzone, or 7% octyl dimethyl para-aminobenzoic acid were tested by the PFA protocol in five laboratories. The test method demonstrated ability to distinguish differences between the protection in the oxybenzone formulations but not between the placebo (0%) and the 7% octyl dimethyl para-aminobenzoic acid formula. The protection factors were independent of the type of skin response. These data support the utility and validity of the PFA method for determining the UVA protection provided by sunscreen products.