UVA? UVB? Deciphering Sunscreen Alphabet Soup
(Sunscreen part 1 of 3)
As I was getting things together for an afternoon at a friends pool, I realized I was almost out of sunscreen. I figured I'd stop by the local drugstore to grab a bottle and be on my way. It was the first time I've bought sunscreen in a couple of years, and I was a little stunned by the selection. There were over 50 choices with claims and counterclaims that read like alphabet soup. UVA? UVB? SPF from 3 to 100? How could I make a reasonable choice from all that noise?
I decided to dig a little and see what all those marketing claims meant. What I discovered was a hodge-podge of regulations and conflicting research that are finally changing after being stalled for 34 years. I'll start with what we know.
The sun puts out a type of light that's invisible to the naked eye. It's called ultraviolet radiation or UV radiation. For decades sunscreen manufacturers have concerned themselves with UVB or ultraviolet B radiation. UVB is what causes your skin to turn red, sunburn and the damage that happens to the uppermost layers of the skin.
UVB is stronger at higher altitudes and it tends to reflect back from surfaces like snow or ice, which is why people get sunburned out skiing, even when the sun isn't that bright. UVB is most prevalent in the midday sun. One of the quirks of UVB is it doesn't do a good job of penetrating glass. That explains why on long road trips, even with the sun shining on you for hours, you're less likely to get a sunburn as long as your windows are rolled up.
Sunscreens were designed to slow the effects of UVB so you could stay in the sun longer without getting burned. Think of "B" for "burned". As long as people came back from the beach without looking like a boiled lobster, everyone thought sunscreen was doing what it should.
Then scientists discovered more about UVA or ultraviolet A radiation. Turns out, 95 percent of the ultraviolet radiation that reaches the Earth's surface is UVA. Because it doesn't produce such an immediate effect, less attention was given to it. But UVA can penetrate clouds, glass and retains nearly the same level of intensity throughout the year. It also has the nasty habit of penetrating more deeply into the skin than UVB. The "A" in UVA should stand for "Aging."
As UVA rays dig into your skin, they damage skin cells called keratinocytes. Those are found in the basal layer of the epidermis. That's also the same place where most skin cancers occur. The more you're exposed to UVA radiation, the higher your chances are of getting skin cancer. Just getting one sunburn with blisters, doubles your risk for malignant melanoma, the most dangerous form of skin cancer.
In a bizarre twist, it appears people who used traditional sunscreens may have put themselves MORE at risk of cancer. By blocking only UVB rays, sunscreens allowed people to stay in the sun longer without burning, but they kept soaking up all those harmful UVA rays.
UVA rays are also the primary form of radiation put out by the lamps used in tanning salons. Some sunlamps put out UVA doses that are 12 times the intensity of the sun! The danger is so extreme, in 2009 the World Health Organization called Sunbeds "carcinogenic to humans" and put them in the same category as cigarettes, alcohol and asbestos.
So what does all that mean for you? Start by looking for sunscreens that provide "Broad Spectrum UVA and UVB Protection."
According to the Food and Drug Administration (FDA), " 'Broad Spectrum' sunscreens protect against both UVA and UVB rays. Scientific data demonstrated that products that are 'Broad Spectrum SPF 15 [or higher]' have been shown to reduce the risk of skin cancer and early skin aging when used with other sun protection measures, in addition to helping prevent sunburn."
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