Suboptimal UVA attenuation by broad spectrum sunscreens under outdoor solar conditions contributes to lifetime UVA burden

Abstract

Broadspectrum sunscreens with a sun protection factor (SPF) of 15 or greater are indicated to decrease the risk of skin cancer and early skin aging caused by the sun if used as directed with other sun protection measures. To determine whether sunscreen product performance is compromised under solar exposure and to test spectral uniformity of protection across the UVA spectrum, we tested broadspectrum sunscreens with a variety of active pharmaceutical ingredients (APIs) and in a variety of dosage forms. A cross-sectional market survey of 32 sunscreen drug products containing either organic or inorganic APIs with SPFs of 15, 30, 50, and 70 was tested. UV doses were delivered via natural sun in Silver Spring, Maryland between June and September of 2017. Of the 32 sunscreen drug products, 6 products failed to meet their broadspectrum claim under solar exposure. Using FDA's new proposal to strengthen sunscreen broad spectrum requirements, spectral uniformity based on the mean sunscreen absorbance of UVA1(340-400nm)/UV (290-400nm) indicated that ~40% of sunscreen drug products tested had suboptimal UVA protection. US consumers may unknowingly be receiving up to 36% more transmitted UVA when selecting between similarly labeled broad spectrum sunscreen drug products with equivalent SPF values. FDA's new proposal may help decrease consumers' overall lifetime UVA burden. Spectral absorbance data on sunscreen performance can be used to further improve the coupling of broadspectrum protection to a product's SPF value so that consumers have improved proportional increases in UV protection.