WASHINGTON – Shade your kids. Strong new evidence suggests overall sun exposure in childhood, not just burns, is a big key to who later develops deadly skin cancer.
The news comes as the government is finishing long-awaited rules to improve sunscreens.
The Food and Drug Administration wants sunscreens to be rated not just for how well they block the ultraviolet-B rays that cause sunburn – today’s SPF rankings – but for how well they protect against deeper-penetrating ultraviolet-A rays that are linked to cancer and wrinkles.
The proposed rules are undergoing a final review and should be issued in weeks, the FDA said.
Still, sunscreen bottles won’t look different any time soon: The proposal will be followed by a public comment period before going into effect.
New research into how the sun and genetics interact points to a possibly more important step consumers can take now. Check the weather forecast for the day’s “UV index” in your town, to learn when to stay indoors or in the shade.
Where you live determines most of your UV exposure. UVA can even penetrate window glass. UV levels vary from state to state, even day to day, because of things like altitude, cloud cover and ozone.
“Sunscreen is imperfect,” warned Dr. Nancy Thomas, a dermatologist at the University of North Carolina who led the UV research. “Schedule activities when UV irradiation is not quite so high.”
Melanoma is the most lethal skin cancer. It will strike almost 60,000 Americans this year, and kill about 8,100. Cases have been on the rise for three decades, and while it usually strikes in the 40s or 50s, doctors are seeing ever-younger cases, occasionally even in children.
Scientists are studying the interaction of genes and UV exposure in melanoma patients in the U.S. and Australia – and initial results suggest staying in the shade in early life is even more important than previously realized.
Some studies show that patients with the most common known melanoma mutations, called BRAF mutations, also had the highest UV exposure by age 20. They also had the most moles, another important melanoma risk factor.
It’s not clear yet, but young, rapidly growing skin may be particularly vulnerable to damaging UV rays, especially as moles are developing, Thomas said. Or maybe early childhood sun exposure spurs moles to develop in the first place.
While sun exposure for young adults played some role, too, the association with BRAF disappeared at age 30.
But that isn’t a license for adults to sunbathe: Another melanoma subtype is strongly linked to UV exposure by age 50, the study found.
Until recently, sunscreens have filtered out mostly UVB rays that cause sunburns, not UVA rays, meaning people who depended only on sunscreen to prevent skin cancer may have gotten a false sense of security.
Today, many sunscreens promise “broad-spectrum” protection against UVA rays, too. But the government doesn’t yet have testing requirements in place to prove that UVA protection.
The term broad-spectrum “means nothing. Anybody can make that claim,” said Dr. Darrell Rigel a past president of the American Academy of Dermatology.
The soon-to-come FDA proposal will keep the SPF, or “sun protection factor,” ratings on sunscreen bottles that refer only to UVB protection but add a UVA rating, too, said Shuren.
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