18719 Assessment of the level of UVA Protection Factor provided by various sunscreens marketed in the US

Abstract

Exposure to ultraviolet A (UVA) and B (UVB) radiation damages skin, causing premature aging and increased skin cancer risk. Although UVB (290-320 nm) is predominantly responsible for sunburn and DNA damage, UVA (320-400 nm) penetrates deeper into the skin, damaging underlying tissue, resulting in the appearance of premature aging. Broad secondspectrum sunscreens provide protection against both types of UV rays and are generally recommended by dermatologists for effective skin protection. However, not all sunscreens formulated as broad spectrum provide the same level of protection against UVA light, even at the same labeled Sun Protection Factor (SPF). The objective was to evaluate the UVA Protection Factor (UVAPF) of commercially available sunscreens and correlate with type of active ingredient and SPF level. Thirty-two products were selected and categorized as mineral, mineral/chemical hybrid, or chemical sunscreens. Sunscreens ranged from SPF 20 to SPF 50+, with an even distribution of products below and above SPF 50. UVAPF of each sunscreen was determined according to in vitro method (ISO24443:2012). Sunscreens with the same SPF across all active ingredient categories showed variability in UVAPF, supporting the fact that the formulation is critical to protective efficacy. Pure mineral and mineral/chemical hybrid sunscreens were determined to exhibit high UVAPF variability, while chemical sunscreens showed results with lower variability within both SPF 20 to SPF 50+ and above SPF 50 products. All chemical sunscreens utilizing the ingredient avobenzone scored high in this assessment and may be the most appropriate choice for patients seeking the highest level of UVA protection.