Sun Exposure and Sun Screens
Millions of people are treated every year for skin cancer and several thousand of these individuals will die from the disease. Approximately 90 % of skin cancer cases are associated with exposure to excessive solar (sun) and artificial ultraviolet radiation (UVR). Sunscreens (SS) can significantly help prevent these cancers as well as prevent premature skin aging. However, SS are often used incorrectly, or not at all, and products used are poorly chosen.
So, what are we trying to get protection from? There are two main types of solar radiation that can damage skin: ultraviolet A (UVA) and ultraviolet B (UVB). UVB damages the most outer layer of the skin and causes sunburn and tanning. However, 95% of UVR that reaches the earth’s surface is UVA and it penetrates the skin much deeper than UVB. Both types of radiation cause skin cancer but the deeply penetrating UVA also causes premature skin aging with wrinkles and crevices from its adverse effect on collagen (deep tissue that supports the outer skin layers maintaining elasticity).
SS are topical agents containing substances that act as filters by deflecting or absorbing UVR. There are two classes of SS: organic (chemical) and inorganic (physical) substances. Organic products absorb and dissipate UVB only and are promoted to prevent sunburn. Inorganic products scatter and deflect both UVA and UVB rays. A “Broad Spectrum” SS is a combination of both classes and provides protection from UVA and UVB. The majority of SS contain ingredients that only block UVB and their effectiveness is quantitated by SPF.
SPF stands for “Skin Protective Factor” and SS are classified by a SPF number from 15 to 100. Theoretically, the higher the number the better the protection. As an example, if a person’s skin, without protection, begins to experience sunburn after 10 minutes of exposure, a 30 SPF SS would provide protection for 300 minutes before burning occurs ( 30 times longer to burn compared to using no SS). An SPF of 15 blocks about 93% of UVB, SPF 30 blocks nearly 97%, SPF 50, 98%, and SPF 100, 99%. So, the difference in benefit between SPF 100 and SPF 30 is not nearly as dramatic as the difference between SPF 30 and bare skin.
While a few percentage points of extra protection is not a bad thing, practically, there is no substantial evidence that indicates purchasing more expensive, super-high SPF SS is warranted because of the negligible increase in protection. Additionally, the higher SPF products tend to be unpleasant because of their stickiness and greasiness and this interferes with compliance.
In summary, a typical adult should follow these guidelines: 1) Obtain a water-resistant, broad spectrum, SPF 30 SS. 2) Pay attention to the expiration date and protect the SS from excessive heat exposure. Both factors can deactivate the ingredients. 3) Apply liberally to exposed skin at least 30 minutes before sun exposure. Most people do not use adequate amounts. 4) Re-apply every 2 hours and if skin become wet by swimming or with perspiration, re-application should be done at least hourly. 5) If skin is oily or hairy, use a gel or lotion preparation; if dry, use a cream. If a spray is used , avoid inhaling the mist. Otherwise, SS are safe and must be FDA approved.
Sun tanning is cosmetically popular, but the fact is that any tan at all indicates damaged skin creating cancer risk and tanning does not protect the skin from further sun exposure. If this appearance is desirable, it is best to use a sunless tanning product.
Have a great summer and enjoy the sunny outdoors but protect your skin with an appropriate sunscreen.
Dr. Tippett is the founder of Comprehensive Quality Healthcare Providers located at 1210 Commerce Dr. Suite 106, Greensboro, Ga. 30642. He can be reached at 706-510-3659. Visit his website www.drtippett.com