UVA filters in sun-protection products: regulatory and biological aspects

Abstract

This review of published in vitro and in vivo studies concerning the biological effects of ultraviolet A (UVA; 320-400 nm) radiation illustrates the evidence for combining UVA and UVB filters in sun-protection products. These data have led to the development of new sunscreens as well as methods to evaluate their efficacy. After listing the UVA filters available and briefly noting the requirements for a high SPF, broad-spectrum sunscreen, the methods for evaluating the level of UVA protection will be described. This article also summarizes several studies looking at the prevention of erythema, pigmentation, DNA damage, photoimmunosuppression, photoaging and photodermatoses. These data demonstrate in vitro and in vivo that only well-balanced UVA-UVB sunscreens, absorbing over the entire UV spectrum are able to prevent or significantly reduce the associated biological damage.

Vemurafenib: an unusual UVA‐induced photosensitivity

“…This common adverse event should be prevented by regular broad-spectrum sunscreen applications with a high UVA photoprotection in association with protective clothes (15,16). This is a new type of phototoxicity that appears immediately with a burning sensation but with an evolution different from solar urticaria.…”

Energy-donor phosphorescence quenching study of triplet–triplet energy transfer between UV absorbers

“…UV-A radiation generates reactive oxygen species (ROS) through the photosensitized reaction with endogenous chromophores. These ROS cause damage to DNA [2][3][4][5]. For the past several decades, sunscreens only protect against UV-B radiation, while UV-A radiation was generally believed to be harmless [1].…”

Need for a well-balanced sunscreen to protect human skin from both Ultraviolet A and Ultraviolet B damage

“…Well-balanced photoprotection has been shown to prevent hyperpigmentation in Asian skin (phototypes III, IV, V). In one study, 6 different sunscreen products, containing UVA + UVB absorbers with different SPF/UVAPF ratios, were tested [6] on volunteers' skin exposed to solar radiation mimicking standard daily UVR. [18,19] The in vivo protection against UVB-and UVAinduced pigmentation was assessed by determining the Pigmentation Protection Factor (PPF).…”

“…Nevertheless, an effective, well-balanced photoprotection against UVB and UVA radiation seems more crucial because of our increasing knowledge of the harmful effects of UVA. [1][2][3][4][5][6] The different aspects of UVA induced damage discussed in this article are summarized in Table 1.…”

“…[1][2][3][4][5] Further, UVA accounts for at least 95% of the solar UV irradiance received at ground level. Hence, sunscreens should effectively protect against UVB as well as UVA radiation [6] The efficacy of a sunscreen is assessed primarily by its sun protection factor (SPF). [7] Since, by definition, the SPF measures the protection against erythema, which is mainly induced by UVB wavelengths; it does not provide information on UVA photoprotection.…”