Not All Sunscreens Are Created Equal
The burning rays of the sun, called ultraviolet B (UVB) rays, are
the primary cause of skin cancer, says Dr. Vincent DeLeo, associate
professor of clinical dermatology at Columbia University. But new
research shows that ultraviolet A (UVA) rays could also increase your
risk for skin cancer, he says.
"This is an area of great controversy, but new studies say that
some skin cancers could be UVA-related," DeLeo says. The reason: These
rays penetrate deeper into the dermis, which is the base layer of the
skin, and weaken the body's immune system, a process called
This could explain why some skin cancers can appear anywhere on
the body, not just where the skin has been directly exposed to the sun,
DeLeo made his remarks this week at the American Academy of
Dermatology's Melanoma/Skin Cancer Detection press conference in New
York City, and in a subsequent interview.
This means people should seek out sunscreens that protect against UVA as well as UVB rays, something not always easy to do.
A sunscreen's sun protection factor (SPF) only measures
protection from UVB rays, not UVA rays, so it's hard to know what
you're getting, DeLeo says.
He cites a study that appeared last January in The Journal of
Investigative Dermatology, an English Journal, in which 119 healthy,
white-skinned men and women were asked to put sunscreen with an SPF of
15 on their buttocks, which had never been exposed to the sun. They
were then radiated with both UVA and UVB rays.
Tests showed the protection against the UVA rays was less than half that of the UVB rays.
"The sunscreen protected against redness, but not against immunosuppression," DeLeo says.
DeLeo says trials are under way in the United States to test
sunscreens that protect against UVA rays, including products that
contain mexoryl and tinosorb. In the meantime, consumers must be
diligent about using other methods of avoiding sun damage.
In addition to applying a sunscreen with a minimum SPF of 15,
people should stay out of the summer sun between 10 a.m. and 4 p.m.,
wear protective clothing, and a broad brimmed hat.
"If you don't get a sunburn, it doesn't mean you're protected from an immunosuppression response," DeLeo says.