Sunscreens – Part I: The problem

Sun behind poleSkin is the largest organ of the human body yet many outdoorsy folks fail to adequately protect their skin from the harmful effects of sunlight (UV radiation). There is plenty of readily available information about sunscreens yet melanoma rates, the most deadly skin cancer, have tripled over the past 35 years. Since summer officially started with the recent summer solstice, I thought that a blog on sunscreens seemed appropriate.

In an attempt to help people protect themselves from UV radiation, the FDA has enacted new guidelines (as of 12/12) for sunscreens. Here are a few of the changes that they have instituted and some reasons why they can be misleading.

Only sunscreens that protect against both UVA (causes lasting skin damage, skin aging and can cause skin cancer) and UVB (causes sunburns, skin damage and can cause skin cancer) radiation may be labeled “broad-spectrum”. But, the FDA’s criteria for protection from UV radiation are the weakest in the modern world and the standard for UVA protection is very weak.

Exposed SunOnly broad-spectrum sunscreens with an SPF (Sun Protection Factor) of 15 or higher may state that they protect against skin cancer if used as directed with other sun protection measures. But this criterion only measures the sunscreen’s ability to filter burning UV rays, which are mainly UVB rays. The SPF does not necessarily indicate the sunscreen’s ability to filter UVA rays.

UVA rays can be equally as damaging as UVB rays because they penetrate deeper into the skin and they may cause a different type of damage to one’s DNA. Since sunscreen use helps to delay sunburns, people spend more time in the sun thinking that they are “safe from the sun”. But UVA rays do not cause sunburn and since most sunscreens are not very effective at filtering them, many people end up with more cumulative exposure to UVA rays without realizing it.

Researchers believe that people may get a false sense of security using sunscreens with high SPF ratings. Thus, they don’t apply enough of it, they wait too long to reapply it and they spend too much time in bright sun. When people apply too little sunscreen or reapply it infrequently, sunscreen can cause more free radical damage than UV rays on bare skin.

Sun Behind TreeSunscreen with an SPF of 15 filters out approximately 93 percent of all incoming UVB rays. SPF 30 filters out 97 percent and SPF 50 filters out 98 percent. Thus, SPF 30 is NOT twice as good as SPF 15. SPF 15 is fine for most people. People who have fair skin, a family history of skin cancer, or conditions like lupus that increase sensitivity to sunlight should consider SPF 30 or higher.

Only sunscreens that protect the skin for 40 (water resistant) or 80 minutes (very water resistant) of sweating or swimming may claim to be “water-resistant”.

Play safe out there!

Dr. Kevin

All photos courtesy Tony Sheppard.

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