Insights and controversies on sunscreen safety

Abstract

Although sunlight provides several benefits, ultraviolet (UV) radiation plays an important role in the development of various skin damages such as erythema, photoaging, and photocarcinogenesis. Despite cells having endogenous defense systems, damaged DNA may not be efficiently repaired at chronic exposure. In this sense, it is necessary to use artificial defense strategies such as sunscreen formulations. UV filters should scatter, reflect, or absorb solar UV radiation in order to prevent direct or indirect DNA lesions. However, the safety of UV filters is a matter of concern due to several controversies reported in literature, such as endocrine alterations, allergies, increased oxidative stress, phototoxic events, among others. Despite these controversies, the way in which sunscreens are tested is essential to ensure safety. Sunscreen regulation includes mandatory test for phototoxicity, but photogenotoxicity testing is not recommended as a part of the standard photosafety testing program. Although available photobiological tests are still the first approach to assess photosafety, they are limited. Some existing tests do not always provide reliable results, mainly due to limitations regarding the nature of the assessed phototoxic effect, cell UV sensitivity, and the irradiation protocols. These aspects bring queries regarding the safety of sunscreen wide use and suggest the demand for the development of robust and efficient in vitro screening tests to overcome the existing limitations. In this way, Saccharomyces cerevisiae has stood out as a promising model to fill the gaps in photobiology and to complete the mandatory tests enabling a more extensive and robust photosafety assessment.

Keywords:

• Sunscreen
• phototoxicity
• UV radiation
• in vitro models
• Saccharomyces cerevisiae

Acknowledgements

The authors gratefully acknowledge the critical reading provided by Dra. Elisabete Pereira dos Santos, Departamento de Fármacos e Medicamentos, Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Brazil and Dr. Carlos Frederico Martins Menck, Instituto de Ciências Biomédicas, Departamento de Microbiologia, Universidade de São Paulo, Brazil.

Declaration of interest

The authors declare that they have no conflict of interest and are solely responsible for the writing and content of the manuscript. The employment affiliations of the authors are shown on the cover page. The institutions with which the authors are affiliated are traditional academies. None of the authors have been involved in legal or regulatory matters related to the contents of the paper.This study was supported by Universidade Federal do Rio de Janeiro (UFRJ) and Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) (Brazil).