Impact of Long-Wavelength Ultraviolet A1 and Visible Light on Light-Skinned Individuals

Solar radiation is known to be a major contributor to the development of skin cancer. Most sunscreen formulations, including those with broad spectrum, offer minimal protection in long-wavelength ultraviolet A1 (UVA1; 370-400 nm) and visible light (VL; 400-700 nm) domain. There is limited information regarding the impact of this broad waveband (VL + UVA1, 370-700 nm) on those with light skin. In this study, ten healthy adult subjects with Fitzpatrick skin phototypes I-III were enrolled. On day 0, subjects' lower back was exposed to a VL + UVA1 dose of 480 J cm^-2 . A statistically significant increase in erythema immediately after irradiation compared with subjects' baseline nonirradiated skin was observed. Clinically perceptible erythema with VL + UVA1 is a novel finding since the erythemogenic spectrum of sunlight has primarily been attributed to ultraviolet B and short-wavelength ultraviolet A (320-340 nm). The results emphasize the need for protection against this part of the solar spectra and warrant further investigation.