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Sun exposure in a nutshell: alluring but dangerous

May 19, 2011

By Colleen Steelquist, Hutchinson Center Science Editor

Sun by Jalal Hameed Bhatti As I write this, the sun is finally out in the Pacific Northwest, a welcome reprieve from an unseasonably dismal and cold spring. It’s one of those days when the weather is a siren call from my workday responsibilities, tempting me to go outside, tilt my head back and soak up the soothing warmth.

A siren call, indeed. Remember the Sirens of Greek mythology? Those seductresses defined the enticing appeal of something alluring but potentially dangerous. That’s sun exposure in a nutshell: alluring but dangerous.

Since May is Skin Cancer Awareness Month, it’s a good time to consider how best to protect yourself daily and especially in the sunny months ahead:

  • Use broad-spectrum sunscreen daily. Most people are fine with SPF 30 sunscreen, but for those at high risk of skin cancer (people with prior skin cancers, those who had severe sunburns as children, and folks with very fair complexions or many moles) sunscreens with an SPF of 50 or more are best. Keep the bottle near your toiletries and make it part of your morning routine, just like shaving or brushing your teeth. I use a moisturizer with sunscreen daily to minimize steps. Don’t skip cloudy days, when 40 percent of harmful rays still reach us. If you work outside, play outdoor sports or spend a lot of time outside, you need stronger, water-resistant sunscreen that stays on your skin better and is less likely to drip into your eyes. Avoiding sunburns is critical: Just one blistering sunburn can double your chances of developing melanoma (the most deadly skin cancer) later in life, according to the Melanoma Research Foundation.
  • Apply enough sunscreen. Many folks do not put on adequate amounts of sunscreen. To cover the exposed areas of your body, you should use about two tablespoons—enough to fill a shot glass—with each use. When we use less, no matter what SPF is printed on the label, we only receive an SPF of about 5. If you’re active or sweating, reapply every two hours.“The sunscreen on the body doesn’t last as long as the SPF of the cream, which is why it’s essential to apply and reapply and reapply—especially on kids,” said Dr. Kim Margolin, a Seattle Cancer Care Alliance physician who treats melanoma patients.
  • Check expiration dates. Most sunscreen bottles are stamped with expiration dates. Generally, the protective chemicals in sunblock degrade after a year and are less effective. Plan to buy new bottles annually.
  • Cover up.  A typical T-shirt only provides an SPF of about 6. But many clothing manufacturers now make shirts and other apparel with built-in high SPF that are breathable and stylish. Don’t forget a broad-brimmed hat and UV-blocking sunglasses.
  • Seek the shade. Especially between 10 a.m. and 4 p.m. when rays are most intense, stay indoors. If that’s impossible, umbrellas and leafy trees offer some protection. Keep babies under 6 months, who can’t yet use sunscreen, out of the sun.

 Year-round, keep these precautions in mind:

  • Avoid tanning beds. Recent studies provide strong evidence linking tanning bed use to melanoma. The research led the World Health Organization’s International Agency for Research on Cancer to declare indoor tanning devices carcinogenic to humans, as risky as tobacco and arsenic.
  • Examine your skin. Check your skin regularly (even areas not exposed to sun), using a handheld mirror for your backside and scalp. The vast majority of moles are harmless and never cause concern. However, any spot or mole that bleeds, itches, hurts, grows rapidly, or changes shape or color needs to be checked as soon as possible by your primary care provider or dermatologist. A complete skin exam should be part of your annual physical.
4 Comments leave one →
  1. Harvey Olsan permalink
    June 15, 2011 1:51 pm

    What active ingredients need to be in the sunscreen, and which ones that are often included should be avoided?

    • June 17, 2011 4:59 pm

      Good questions, Harvey. The Melanoma Research Foundation suggests you look for one of these active ingredients in your sunscreen: zinc oxide, titanium dioxide or mexoryl. While the Food and Drug Administration continues to look into the safety of ingredients used in sunscreens, they have now been studied in labs and on live subjects by research scientists for years. The foundations says the evidence that sunscreens are safe and effective is overwhelming. Consumers have also questioned the safety of sunscreen ingredients that have been processed into tiny particles, called nanoparticles. However, current research indicates that fears about the absorption of nanoparticles are unwarranted. Sunscreen is applied to the outermost layer of the skin (the stratum corneum), which is made up of dead skin cells. Several studies have shown that nanoparticles do not penetrate living skin.
      –Colleen Steelquist

  2. Carl Berkowitz permalink
    July 1, 2011 4:32 pm

    How is the SPF rating determined and what exactly is UV-B?

    • July 5, 2011 5:15 pm

      Thanks for your questions, Carl. There are two types of solar rays: short ones called ultraviolet B (UVB), which cause burning, and long ones called ultraviolet A (UVA), which are linked to wrinkling. Both types of rays can lead to skin cancer. Unless you’re using a broad-spectrum sunscreen, the SPF (sun protection factor) ratings reflect only the extent of the sunscreen’s protection against UVB. The higher the SPF rating (a laboratory measure determined by manufacturer and FDA testing), the longer one can stay in the sun before burning. However, the true protective time depends on the skin type of the user, the amount of sunscreen used and the activities of the user.

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