The hairless mouse as a model for evaluating sunscreens. Prevention of ultraviolet B inhibition of epidermal DNA synthesis.

A sunscreen's effectiveness is usually determined by its ability to prevent ultraviolet (UV) radiation-induced skin erythema. This criterion requires subjective interpretation. We propose a new method of evaluating sunscreens based on the known effect of UV-B radiation (290 to 320 nm) to inhibit DNA synthesis. Using hairless mice, we found that sulisobenzone (Uval) and aminobenzoic acid (PreSun) sunscreens differ substantially in their ability to prevent inhibition of epidermal cell DNA synthesis by UV-B radiation. By estimating the UV-B dose required to inhibit DNA synthesis by 50%, with and without sunscreen, a protective factor of 5.6 and 14.4 was calculated for sulisobenzone and aminobenzoic acid, respectively. This technique is an objective way to evaluate sunscreen effectiveness and could be a useful screening procedure for sunscreen preparations before final efficacy testing in humans.