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.

“You have to be careful even if the temperature is minus 10 on the ski slope. Another population group at risk from radiation through glass is that of pilots,” she says.

Whether called a block or screen, innumerable choices and brand names with various levels of protection beckon the conscientious consumer easily confused by vague descriptions such as “high protection,” “unique UVA filter,” and “broad spectrum UVA/UVB protection.” The number prominent on all labels — the usual range being 15 to 60 — refers only to the amount of protection offered from UVB radiation in terms of time, not the relative strength of the product. At present, a consumer has little or no idea of the relative value of UVA protection in each formula.

The FDA is considering proposals for grading protection offered from UVA rays as well. The most likely result would be a simple star system from one to four indicating fair, good, better or excellent protection.

The agency also maintains, as do many doctors and scientists, that little evidence exists about the absolute value of any external surface agent in preventing skin cancer.

Many medical professionals worry about a false sense of security represented by those products when factors such as genetics and the environment likely play an important role as well.

Questions arise in winter, too, about the best means of acquiring Vitamin D, important for bone health, since sunlight is needed to convert that vitamin in the body. “You are getting some sun even with a block, ” says Dr. McKinley-Grant, noting that a normal American diet contains some Vitamin D and that “you get daily sun exposure when driving to work. If you live and work in the dark all day that will be an issue and you should be aware that you need [sun].”

Dr. Kauffman goes one step further in advising people to take a calcium supplement containing Vitamin D year-round unless a person is prone to kidney stones.

There is evidence that melanoma is on the increase, although, in Dr. Kauffman’s words, “no one knows how to explain whether the cause is people spending more leisure time in the sun, the decreased ozone filtration of harmful rays, or different patterns of exposure as opposed to the chronic exposure experienced by people who grow up around or work on the sea.”

Dr. Leffell is adamant, too, about what he calls “practicing good behavior” since studies have shown that people using sunscreens correctly “get fewer precancerous growths.” But he calls sunscreen use “just one part of a total protection issue, which includes avoiding the sun during peak hours of the day.”

The American Academy of Dermatology warns that, at current rates, one person dies of melanoma every hour, and an estimated 10,850 people will die of skin cancer this year.