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“Ultraviolet (UV) radiation is one of the main environmental factors associated with skin damage”, said Caroline de Melo Fantato, a researcher at USP’s School of Engineering (Poli) and the article’s first author, in an interview with Jornal da USP. “Excessive and cumulative exposure to UV radiation is related to photoaging, changes in pigmentation, immunosuppression, and most importantly, skin cancer.”
“In this context, sun protection should not be viewed merely as an aesthetic issue. It is an important strategy for preventing health damage, especially given daily sun exposure and the high incidence of skin cancer”, she emphasized. “Sunscreens are one of the tools available to reduce exposure when used properly alongside other measures, such as avoiding exposure during peak radiation hours, wearing protective clothing, and seeking shade.”
The researcher explained that the study aimed to provide a thorough and integrated analysis of sunscreen filters, considering not only their ability to protect against ultraviolet (UV) radiation, but also aspects related to formulation, stability, toxicological safety, efficacy, and environmental impact. “The review aimed to understand how the chemical and physicochemical characteristics of the filters influence their behavior in formulations, as well as their safety and performance”, she stated. “We also evaluated more recent strategies, especially those based on nanotechnology and materials science, which can contribute to the development of safer, more effective, and more sustainable sunscreens.”
“We analyzed the scientific literature on the main organic and inorganic UV filters, as well as different formulation strategies”, reported Caroline. “The review was structured around four main aspects: the mechanisms of action and characteristics of the filters, safety and regulatory issues, innovative formulation strategies, and aspects related to sustainability.”
Performance and safety
The study considered factors such as photostability, systemic absorption, the potential to generate reactive oxygen species, photoprotective efficacy, filter behavior on the skin, and possible environmental impacts. “We also discussed strategies such as nanoencapsulation and surface functionalization of nanoparticles, as well as emerging materials such as magnesium oxide, which shows promising characteristics for photoprotection applications”, the researcher explained. “Sunscreens are important tools for photoprotection, but not all formulations or filters are equally safe or effective.”
One of the issues discussed regarding toxicological safety is the possibility of the systemic absorption of certain organic filters, as well as concerns related to their stability and the transformation products generated during exposure to radiation. “In the case of inorganic filters, such as titanium dioxide and zinc oxide, the generation of reactive oxygen species and the behavior of nanoparticles also need to be considered”, said Caroline.
In terms of efficacy, the photoinstability of certain filters can affect the performance of the formulation during sun exposure. “Furthermore, characteristics such as spreadability, film formation on the skin, transparency, and formulation stability directly impact both the protection provided and consumer acceptance of the product”, clarified the researcher.
“Sunscreens are important tools for photoprotection. However, not all formulations or filters have the same safety and performance characteristics.”
From an environmental perspective, there is growing concern about the release of UV filters and other formulation components into aquatic environments. “There are still significant gaps in our understanding of the ecotoxicological effects of different filters and how they behave in the environment”, the researcher emphasized. “Therefore, the development of sunscreens must consider consumer safety and the environmental impact throughout the product’s life cycle.”
Scientists recommend developing new sunscreens in an integrated manner that simultaneously considers safety, efficacy, stability, and sustainability. “Formulation engineering strategies can improve filter stability and control their interaction with the skin”, noted Caroline. “One possibility is the nanoencapsulation of filters with stability issues. Another is the surface functionalization of nanoparticles, which can modify their properties and reduce certain limitations.”
The researcher stated that it is also important to invest in the development and evaluation of new multifunctional materials. “Magnesium oxide, for example, was discussed in the review as a potential alternative for photoprotection applications due to its UV-scattering properties and antioxidant and anti-inflammatory characteristics”, she said. “However, it is important to emphasize that emerging materials still need to undergo systematic evaluations of safety, efficacy, and environmental impact before they can be considered established alternatives to current filters.”
Integrated knowledge
The study was conducted by Caroline de Melo Fantato and Jorge Alberto Soares Tenório from the Department of Chemical Engineering at the School of Engineering and André Rolim Baby from the School of Pharmaceutical Sciences at USP. The study is associated with activities conducted at the School of Engineering’s Laboratory of Recycling, Waste Treatment, and Extraction (Larex), as well as the SunLab Research Group, which specializes in photoprotection research and the development of cosmetic products.
“Collaboration among different areas at USP was crucial for taking a multidisciplinary approach to the topic and integrating knowledge from chemical engineering, materials science, nanotechnology, cosmetic technology, and photoprotection”, concluded Caroline. This study was funded by the São Paulo Research Foundation (Fapesp), the National Council for Scientific and Technological Development (CNPq), and the Coordination for the Improvement of Higher Education Personnel (Capes).
The article Sunscreen and UV filters: a comprehensive review of formulation, safety, and efficacy is available online.
More information: email carolfantato@usp.br, with Caroline de Melo Fantato
English version: Nexus Traduções, edited by Denis Pacheco
