Too much of a good thing . . .

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I’ve heard I’m supposed to wear sun block all the time, so I’ve been using an SPF 15 that’s included in a moisturizer.  If I use a higher SPF on a daily basis, is there anything nasty in it that wouldn’t be good to have on my skin 24/7/365?

A great question for the first day of summer!

There are quite a few rumors out there about sunscreens. Let’s shed some light on the subject:

  • A high SPF guarantees protection: There are two kinds of risky rays: UVA and UVB. Believe it or not, the present rating system is only for UVB. An SPF of 8 billion may tell you that you could walk on the surface of the sun without a single UVB ray getting to you, but it says nothing about how many UVA rays will microwave your skin when you’re walking around the Oval. The FDA is working on this, but for now, it’s all we’ve got.
  • The higher the SPF the better: There’s actually not a lot of incremental benefit as SPF increases. Going from SPF 15 to SPF 30 only blocks about 3% more UVB, and going from 30 to 40 only improves things by about 1%. Higher SPF products can cause more allergic reactions to product ingredients so if you want to go higher than 15, going over 30 probably won’t provide much extra benefit. Regardless of SPF, you should always apply sunscreen generously and reapply often.
  • Sunscreens cause cancer: There is a mountain of evidence that sunscreen prevents skin cancers, particularly squamous cell carcinomas. There was some speculation that if newer ingredients like oxybenzone, avobenzone, titanium and zinc oxide (for UVA protection) were absorbed through the skin they might mess with estrogen and testosterone levels and put people at an increased risk of cancer but there’s no evidence that this actually occurs in humans.
  • Never, ever go out in the sun without protection: You will never be sorry you used sunscreen on your face. Leaving the issue of cancer aside, sun supercharges wrinkles and other signs of age (sagging, discoloration). For the rest of your body, though, it’s not as clear. The problem is partly with our climate. We need sun to convert precursors in our skin to Vitamin D. Given that we spend several months of the year practically sun-free, many Buckeyes have Vitamin D deficiency. While there is some evidence that low levels increase our risk for certain cancers, there are real risks of Vitamin D deficiency, for example, osteoporosis and an oldie but a goodie, rickets. It doesn’t take a lot of sun exposure to generate Vitamin D production in the skin, only 10-15 minutes a few days a week.

In general you’re okay if you:

  • Apply sunscreen generously and reapply every couple hours if you must remain outside.
  • Stick with a sunscreen with an SPF of 15-30.
  • Look for a sunscreen that offers UVA and UVB protection. Look for the American Academy of Dermatology seal of approval.
  • Here in Central Ohio, it’s probably okay to skip the sunscreen for brief exposures of 10-15 minutes two-three times a week during non-peak hours. (Peak hours are 10am-4pm). Cover up that face, though.
  • If you’re worried about your Vitamin D supply, schedule an appointment to discuss a diagnostic blood test and/or dietary replacement with your healthcare provider.

For more than you ever wanted to know about UVA, UVB, and the evidence about sunscreen, cancer, and toxicity, click here.

Victoria Rentel, MD (OSU SHS)

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