Characterization of the UVA protection provided by avobenzone, zinc oxide, and titanium dioxide in broad-spectrum sunscreen products.

Abstract

Solar UV radiation (UVR) is composed of UVB (290-320 nm) and UVA (320-400 nm) wavelengths. Only two sunscreen active ingredients approved in the US, avobenzone (butylmethoxydibenzoylmethane) and zinc oxide (ZnO), provide true broad-spectrum protection against UVA wavelengths >360 nm. Although effective against shorter UVR wavelengths <360 nm, titanium dioxide (TiO(2)) is also often believed to confer broad-spectrum protection and is substituted for ZnO or avobenzone. To sustain its absorption capacity within a sunscreen film during UVR exposure, avobenzone needs to be formulated into sunscreen products using sound formulation strategies.