BNL Study on Skin Cancer/Sunscreens

[Mike Grissom <mikeg@SLAC.Stanford.EDU>]

Radsafers,

I noticed awhile ago that our colleagues in Australia
and other sunny locals (definitely not California lately)
were interested in more information relating to sun
exposure and skin cancer.

This recent news release from the Brookhaven National
Laboratory (New York, USA) may be of interest to them
in particular.

S.,

MikeG.

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#98-09 Contact: Mona S. Rowe, or Kara Villamil
EMBARGOED UNTIL 2/17/98, 12:30 p.m.

                  SUNSCREENS THAT STOP SUNBURN
                DON'T ALWAYS PREVENT SKIN CANCER

    Melanoma Rates May Have Risen Due to Inadequate Protection

PHILADELPHIA - Just because a sunscreen keeps you from getting
sunburned doesn't necessarily mean it will prevent all skin
cancers, a researcher from the U.S. Department of Energy's Brookhaven
National Laboratory reports.

In fact, says noted radiation effects researcher Richard Setlow,
the use of sunscreens that don't block all the harmful rays in
sunlight may actually be partly to blame for the steady five
percent annual rise in melanoma rates among whites. And, he says,
any depletion of the global ozone layer may not lead to more
melanomas after all because the most cancer-causing rays already
pass through the layer.

Dr. Setlow, a senior biophysicist at BNL, presented his team's
findings today at the annual meeting of the American Association
for the Advancement of Science. "Traditionally, sunscreens have
only blocked the transmission of a kind of ultraviolet light in
sunlight that's known as UV B," Setlow said.  "That's the range of
wavelengths that cause sunburn, or erythema. It's also the kind of
UV that the DNA in our cells absorbs most easily."

"But we have found that another range of wavelengths, collectively
called UV A, may be much more powerful in causing skin cancers
called melanoma," Setlow continued. "Our research shows that about
90 percent of sunlight's melanoma-causing effect may come from UV
A and only 10 percent from UV B." Still, he said, UV B is the
chief cause of other skin cancers besides melanoma.

The distinction between the two kinds of UV light makes a
difference, Setlow said, when sunlight encounters the Earth's
dwindling ozone layer. "Since the ozone layer only blocks UV B,
depleting it probably won't cause melanoma rates to rise any
faster than they are already." But, he added, ozone depletion
will probably still worsen other effects in humans, animals and
plants alike.

"Brookhaven researchers such as Dr. Setlow have contributed
immeasurably to our knowledge of the health effects of
radiation," said Energy Secretary Federico Peņa. "I'm glad that
the Department of Energy's expertise in this area can help
educate Americans on important public health issues."

Because studying skin cancer causes in humans would take decades,
Setlow and his team reached their conclusions about UVA's danger
by studying a special hybrid fish. Called Xiphophorus, the fish
lack most of the genes needed to prevent melanoma.

After extrapolating their fish results to humans, Setlow and his
colleagues found confirmation for their theory in a comparison
of epidemiological studies of melanoma rates among Australians
and Norwegians, and in a study of melanoma among sunscreen users
and non-users in Europe.

Melanoma, called "the most serious form of skin cancer" by the
American Cancer Society, is a cancer of pigment-producing skin
cells that is expected to strike about 41,600 persons in 1998.
Since 1973, the incidence rate of melanoma has increased about 4%
per year from 5.7 per 100,000 people in 1973 to 12.5 per 100,000
people in 1994. The ACS says it expects an estimated 9,200 skin
cancer deaths this year, 7,300 from melanoma and 1,900 from
other skin cancers.

Setlow has devoted decades to the study of the biological effects
of UV light and other forms of radiation. Most recently, he
chaired the Committee on Health Risks of Exposure to Low Levels
of Ionizing Radiation, Phase I, convened by the National Research
Council of the National Academy of Sciences. In 1996, he chaired
the NRC committee that studied the potential health effects from
long-term exposure to space radiation.

A 1988 winner of the Enrico Fermi Award, the most prestigious
scientific honor given by DOE, Setlow is also BNL's Associate
Director for Life Sciences. He holds a 1947 Ph.D. in physics
from Yale University, and has worked at BNL since 1974.

Brookhaven National Laboratory carries out basic and applied
research in the physical, biomedical and environmental sciences
and in selected energy technologies. Brookhaven is operated by
Associated Universities, Inc., a nonprofit research management
organization, under contract with the U.S. Department of
Energy.

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