Background: Ultraviolet (UV) radiation is a main cause of aging of sun-exposed skin, but greater attention is being focused on the damaging effects of high-energy visible (HEV) light (400 and 500 nm). HEV light exposure has increased with expanding use of consumer electronics, such as smartphones, which have a peak emission in the 400-490 nm range. Sunscreens containing titanium dioxide and zinc oxide protect against UVA and UVB radiation but provide limited protection against HEV light.
Aim: Iron oxides including red iron oxide (Fe2 O3 ), yellow iron oxide (Fe(OH)3 /FeOOH), and black iron oxide (Fe3 O4 ) effectively block HEV light, each with a different attenuation profile. Zinc oxide, titanium dioxide, and iron oxides with patented skin care ingredients have been incorporated into several formulations to provide enhanced skin protection (Colorescience, Inc).
Methods: The percent of HEV light attenuation from 400 nm to 490 nm light was measured in vitro using a technique known as diffuse transmittance spectroscopy using a Perkin Elmer Lambda™ 750 UV/Vis/NIR Spectrophotometer equipped with a 100-mm integrating Labsphere® and PbS detector.
Results: Products formulated with zinc oxide, titanium dioxide, and iron oxides demonstrated 71.9%-85.6% attenuation across the tested wavelengths of 415-465 nm.
Conclusion: Sunscreens formulated with iron oxides provide enhanced protection against blue light, especially when combined with zinc oxide. To our knowledge, similar studies with iron oxides have not been performed.
Keywords: high-energy visible light; iron oxides; photoaging of the skin; photoprotection.
© 2020 The Authors. Journal of Cosmetic Dermatology published by Wiley Periodicals LLC.