Determining the impact of active ingredients on sunscreen UV resistance

Abstract

In our continued efforts to eradicate skin cancer and other photodamaging effects caused by ultraviolet (UV) radiation, sunscreening agents have become our primary defense. However, despite the undeniable benefits of sunscreen, concerns have been raised due to the carcinogenic properties of several of their common active ingredients. Additionally, previous research has shown the unreliability of using sun protection factor (SPF) as a measure of sunscreen photoprotective ability. Given these considerations, this study set out to determine the impact different active ingredients would have on sunscreen UV resistance. It was hypothesized that the active ingredients’ UV absorbance spectrum would provide a better predictor of sunscreen photoprotection. In this report, three different sunscreens were chosen – one with titanium dioxide, one with benzophenone derivatives, and one with salicylates – to provide a broad range of tested sunscreens. Due to their similarity with human DNA, Saccharomyces cerevisiae was cultured and used as a model system for these experiments. By comparing the percentage decrease of live cells protected with sunscreen relative to a control (i.e. no exposure to UV radiation), it was found that a titanium dioxide-based sunscreen was the most effective. Notably, all three sunscreens tested had an SPF 50, yet yielded different results in photoprotective ability.