Development of sunscreen toward high UV protection and less toxicities: A review

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The growing incidence of ultraviolet (UV)-induced skin disorders has intensified the demand for sunscreen formulations that combine effective photoprotection with improved human and environmental safety. Conventional inorganic UV filters, such as titanium dioxide and zinc oxide, provide broad-spectrum protection and excellent photostability but may generate reactive oxygen species (ROS) under UV irradiation and often exhibit poor cosmetic acceptability. In contrast, widely used organic UV filters, including avobenzone, oxybenzone, and octocrylene, offer better aesthetic performance but remain associated with photodegradation, systemic absorption, endocrine-related bioactivity, and environmental persistence. These limitations have stimulated the development of alternative UV-filtering materials together with advanced formulation strategies. This review critically discusses recent advances in sunscreen technologies, covering conventional inorganic and organic UV filters, emerging bio-derived photoprotective compounds, and nanotechnology-based delivery systems. Particular emphasis is placed on how material engineering strategies, including surface modification, elemental doping, encapsulation, and hybrid nanostructure design, improve photostability, suppress photocatalytic ROS generation, enhance formulation performance, and reduce human and environmental risks. The review also examines the mechanistic basis of sunscreen toxicity by integrating current evidence on oxidative stress, phototoxicity, genotoxicity, endocrine-related bioactivity, human bioavailability, and ecotoxicological effects. These discussions are complemented by recent advances in formulation engineering aimed at improving both safety and long-term photoprotective performance. Current challenges and future opportunities for sunscreen development are also discussed, with particular attention given to multifunctional materials that combine high UV protection, long-term stability, favorable sensory properties, and environmental sustainability. By integrating advances in materials science, toxicology, and formulation engineering, this review provides a comprehensive perspective for the rational development of safer and more sustainable next-generation sunscreen technologies.