Iron oxides in novel skin care formulations attenuate blue light for enhanced protection against skin damage

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 (Fe(2)O(3)), yellow iron oxide (Fe(OH)(3)/FeOOH), and black iron oxide (Fe(3)O(4)) 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.