UVA and UVB formulation phototoxicity in a three-dimensional human skin model: Photodegradation effect

Abstract

In vitro three-dimensional human skin models are an innovative alternative to evaluate cytotoxicity and phototoxicity in the cosmetic industry. The aim of this study was to use a skin model to evaluate the potential toxicity of sunscreen formulations with or without exposure to UV radiation. In addition, the toxicity of these formulations was evaluated after exposure to photodegradation. The results showed toxicity with all formulations/conditions tested, including the control formulation, compared to PBS. Cell viability of photodegraded formulations - prior to the phototoxicity radiation process - was higher, indicating that some formulation components were degraded into products with reduced toxicity. The results also indicated that avobenzone was more unstable/toxic than octyl p-methoxycinnamate under the same test conditions. The sunscreens and their formulations were shown to be toxic to skin model cells to some extent, even when not exposed to UV irradiation; however the biological role of this toxicity is unclear. This result shows the importance of testing sunscreen formulations in real in-use conditions. Finally, since we used an in vitro assay based on a human cell model, this non-invasive technique represents a suitable alternative to animal models for phototoxicity tests in general and could have application in screening new sunscreen products.

Replacement of animal testing by integrated approaches to testing and assessment (IATA): a call for in vivitrosi

“…Moreover, the use of a mouse cell line has been criticized and the substitution of 3T3 cell line with human keratinocytes was proposed, to provide a more realistic experimental model with respect to the human situation (Clothier et al 1999 ; Maciel et al 2019 ). To date, 3D human skin models represent a flexible tool to investigate skin alterations after chemical exposure, including phototoxicity, since they take into account also some relevant in vivo parameters as skin penetration or stratum corneum barrier function (uco Dayane et al 2018 ; Kim et al 2020 ). In this respect, the new OECD TG 498 (OECD 2021a ) fully reflects these aspects; it is based on the in vitro test system of the RhE, which closely mimics biochemical and physiological properties of the human epidermis (Dellambra et al 2019 ).…”

Sunscreen and Suntan Preparations

“…Avobenzone induces mitochondrial dysfunction-mediated apoptosis leading to abnormal placentation during early pregnancy [53]. Avobenzone was more unstable/toxic than octyl p-methoxycinnamate (an organic UV-B filter originally developed in the 1950s, has been one of the most widely used sunscreens for decades) [54,55]. Octocrylene helps stabilize avobenzone, which is good, but it is a known endocrine disruptor that also releases free radicals [57].…”

A Pharmacological Review of Sunscreen and Suntan Preparations

“…Avobenzone induces mitochondrial dysfunction-mediated apoptosis leading to abnormal placentation during early pregnancy [85]. Avobenzone was more unstable/toxic than octyl p-methoxycinnamate (an organic UV-B ilter originally developed in the 1950s, has been one of the most widely used sunscreens for decades) [86,87]. Octocrylene helps stabilize avobenzone, which is good, but it is a known endocrine disruptor that also releases free radicals [88] (Figure 9).…”