Despite the numerous benefits of sunlight, ultraviolet (UV) radiation have a key role in developing numerous skin damages like erythema, photoaging and photocarcinogenesis. Although the cells have endogenous defense systems, they may not efficiently repair damaged DNA at chronic exposure. Thus, it is essential to use artificial defense strategies such as sunscreen formulations. 

UV filters must scatter, reflect or absorb solar UV radiation to prevent direct or indirect DNA lesions. Yet, the safety of UV filters is concerning due to several controversies reported in the literature, like endocrine alterations, allergies, increased oxidative stress, phototoxic events, etc. Despite these controversies, sunscreens′ testing method is crucial to ensure safety. Sunscreen regulation contains a mandatory test for phototoxicity; however, photogenotoxicity testing is not recommended as a part of the standard photo safety testing program. The available photobiological tests are still the first approach to assess photo safety; however, they are scarce. Few available tests only sometimes provide reliable results, primarily due to limitations concerning the nature of the assessed phototoxic effect, cell UV sensitivity and the irradiation protocols. These factors debate the safety of sunscreen-wide use and demand robust and efficient in vitro screening tests to overcome the existing limitations. Accordingly, Saccharomyces cerevisiae is a promising model to fill the gaps in photobiology and to complete the mandatory tests allowing a more extensive and robust photo safety assessment.

Source: Paiva JP, Diniz RR, Leitão AC, et al. Insights and controversies on sunscreen safety. Crit Rev Toxicol. 2020;50(8):707-23.