Screening oneself from the sun’s rays

In winter, people need to avoid the sun’s harmful rays as much as they do in summer, but the habitual use of sunscreen or block is only part of the job, dermatologists agree.

What they do not always agree upon, however, is the value of products relatively new to the U.S. market containing a drug called Mexoryl SX.

Two local doctors assert that it is the closest chemical formula yet devised for helping screen people from ultraviolet light rays known familiarly as UVA and UVB that are the enemy of healthy skin. They are joined in this view by Dr. Sonia Badreshia-Bansal, a California physician who is an adjunct clinical professor at Stanford University.

However, Dr. David Leffell, a professor of dermatology at the Yale School of Medicine, takes issue with their confidence in Mexoryl’s power, suspecting “a lot of hype” was involved in its promotion.

Other new patented technologies approved recently by the Food and Drug Administration include Helioplex; they all help stabilize a common sunscreen ingredient known as avobenzone, thus allowing further protection, notes Dr. Badreshia-Bansal.

Mexoryl-enhanced products do filter both the longer UVA rays as well as shorter UVB rays, says Dr. Leffell, but it is a question of degree. “Mexoryl picks up only a very tiny amount of UVB,” he says, adding that “UVB is the one firmly established to cause cancer.”

UVA, he says, “traditionally is considered more deeply penetrating and acts as a change agent in the skin.” A UVA block, therefore, would help prevent classic signs of aging such as wrinkles and discoloration. (Screens chemically absorb UV rays; blocks chemically deflect them.)

UVB is associated with a classic sunburn and non-melanoma skin cancer, and “damage occurs with everyday continuous exposure,” Dr. Badreshia-Bansal says. One other distinction, notes Dr. Lisa Kauffman, chief of dermatology at Georgetown University Medical Center, is that “UVB doesn’t go through glass and UVA does.”

“Mexoryl,” she says, “blocks both.” So incidentally, she adds, does zinc oxide, a much heavier substance often used for diaper rash.

Titanium oxide acts as a physical block like zinc oxide and quite a few protective agents contain it because it can be ground finely — micronized — to form a semi-clear physical block that reflects the rays like a mirror, she says. Both titanium oxide and a chemical formula whose trade name is Parsol 1789 help protect against UVA light.

“But Mexoryl is more effective,” agrees Dr. Lynn McKinley-Grant, a Washington Hospital Center dermatologist.

The important thing, says Dr. McKinley-Grant, is to make a habit of using sunscreen because “the sun rays in winter are still there. People think about them less because of lower temperatures, but the rays still have the same strength. You can get a terrible sunburn at high altitudes.”

She points to the skin of some homeless people where “you can see an incredible amount of skin damage. You want to protect skin from that because we know there is a 15-year delay in damage consequences.”

Fair-complexioned persons who burn easily are more susceptible and should take greater care, she warns, but it’s necessary for everyone in winter to protect eyes, ears, neck and hands as well as the face.

Melanoma, the most serious form of skin cancer, is prevalent at greater rates year-round in the sunny climes of Florida and California — but also in Colorado where rays reaching the Earth’s surface at high altitudes are filtered less through the ozone layer, Dr. Kauffman explains.

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