The Science of Sunscreen

The presentation covers the science behind sunscreens, focusing on ultraviolet (UV) radiation, its types (UVA and UVB), the importance of sun protection factor (SPF), and how sunscreens work. UV radiation constitutes about 5% of the solar spectrum that reaches the Earth's surface, with UVB primarily causing sunburn and UVA contributing to skin aging. Recommended behaviors for reducing skin cancer risk include using broad-spectrum sunscreens (SPF 30 or higher) that protect against both UVA and UVB, applying sufficient amounts, and reapplying after swimming or sweating. Sunscreens contain organic and inorganic filters, with both types providing protection through absorption of UV rays. Effective testing methods for SPF involve applying a standard amount of sunscreen to skin and measuring response to UV exposure. The presentation notes potential reasons for sunscreen failure, such as uneven application and insufficient reapplication frequency. Lastly, it addresses the emerging issue of visible light-induced skin effects and calls for better testing and standards for sunscreen to cover this aspect, highlighting the need for advancements in photo protection methods and rigorous testing protocols.