The sun generates two main types of skin-damaging ultraviolet (UV) rays: UVA and UVB. UVA is capable of deeply penetrating the skin and can lead to the formation of wrinkles, skin spots and other signs of premature aging. UVB can cause the skin to burn, tan and develop cancerous lesions. Shielding the skin from both UVA and UVB rays is the only way to avoid these problems.
Sun protection factor, or SPF, is a measure of a sunscreen’s ability to filter UVB rays and prevent them from reaching and damaging the skin. In essence, SPF can be explained as follows: If it takes 20 minutes for unprotected skin to redden in the sun, the use of an SPF 15 sunscreen will prevent the skin from reddening for 15 times longer (in this example, about five hours).
While it’s true that a higher SPF rating can provide more protection against UVB rays, any increase above SPF 30 is negligible. Plus, many experts point out that sunscreens with very high SPF ratings can provide a false sense of security and encourage people to neglect other protective behaviors, such as seeking shade and wearing protective clothing.
What’s more, the combination of UVA and UVB rays generated by the sun is very powerful, and it’s important to remember that UVA rays can cause skin damage without sunburn. Therefore, in addition to having a high SPF rating to shield the skin from UVB rays (many experts recommend SPF 30), a sunscreen must provide multi-spectrum, broad-spectrum or UVA/UVB protection to be truly effective.
With that in mind, here are some important ingredients to look for when choosing a sunscreen:
- PABA derivatives, salicylates or cinnamates (octylmethoxycinnamate or cinoxate) – to absorb UVB rays
- Benzophenones (oxybenzone or sulisobenzone) – to protect against short-wave UVA rays
- Titanium dioxide, zinc oxide, avobenzone or ecamsule – to shield against the remaining UVA spectrum
The importance of comprehensive UVA and UVB protection cannot be overstated. But, keep in mind that even the most protective sunscreens cannot be expected to remain fully effective for longer than two hours without being reapplied. In order to achieve the maximum benefits of wearing sunscreen, it is necessary to apply 1 ounce (approximately a shot glass full) 30 minutes prior to sun exposure, and then reapply that same amount every two hours and immediately after swimming, toweling off or sweating.
The multispecialty team of experts in the Cutaneous Oncology Program at Moffitt Cancer Center offers individualized advice and comprehensive services for all types of skin cancer, including the latest options in prevention, screening, diagnostics and treatment. If you’d like to learn more, call 1-888-663-3488 or complete a new new patient registration form online. No referrals are needed.