More on Sunscreen Issue and UV Wavelengths

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

Radsafers,

An additional article on the possible limitations with a
'non-ionizing' radiation protection measure (sunscreens)
is shown below.

Regarding the question of wavelengths of UV, the following
is my interpretation of data in Figure 16.2.3 in the new
"Handbook of Health Physics and Radiological Health," 3rd
edition; Shleien B., Slaback, L.A., and Birky, B.K.; Williams
& Wilens, Baltimore, 1998:

	UV-A	315 - 400 nm
	UV-B	275 - 315 nm
	UV-C	100 - 275 nm

Ciao,

MikeG.

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The following was in the February 18, 1998 edition of the
San Mateo County Times (California, USA):

STUDY CASTS SHADOW ON EFFECT OF SUNSCREENS

Associated Press

PHILADELPHIA--A provocative presentation at a science
conference Tuesday questioned the widely held belief that
sunscreens lower the risk of deadly melanoma skin cancer, but
specialists still caution against going into the sunshine
without these lotions.

Sunscreens prevent sunburns, and since there is evidence that
frequent burns, especially at an early age, trigger melanoma,
many experts assume that using them should help ward off this
cancer.

However, melanoma cases have risen dramatically over the last
25 years even as sunscreen use has become more common.  The
lethal cancer now strikes about 42,000 Americans a year,
killing 7,300.

Dr. Marianne Berwick, an epidemiologist at Memorial
Sloan-Kettering Cancer Center in New York City, said her own
study, as well as a review of other research, offers no
convincing evidence that using sunscreens keeps people from
getting melanoma.

"It's not safe to rely on sunscreen," she said.

Ten studies have looked at the question, she said at the
American Association for the Advancement of Science meeting
[AAAS 1998 Annual Meeting].  Three of them, including her own,
found no link between sunscreens and melanoma risk.  Two
suggested that sunscreens seem to prevent melanoma.

The five others found that melanoma risk actually increased
among sunscreen users--probably because people who use them
most are already at highest risk because of light complexions.

Several dermatologists strongly disagreed with Berwick's report.

Until there is clear proof that sunscreens are ineffective, "it
would be irresponsible to discontinue all recommendations about
using sunscreens," said Dr. Darrell Rigel of New York
University.

Dr. Michael Thun, director of analytics epidemiology at the
American Cancer Society, said:  "People should not stop using
sunscreen because of this study," he said.  "The important
message is that using sunscreen is only one of several measures
to reduce one's risk of skin cancer."

Melanoma may take 20 years or more to develop after excessive
sun exposure.  Some doctors argue that it is simply too soon to
prove that sunscreens are helping, since No. 15 and stronger
sunscreens have been in wide use since only the mid-1980s.

Dr. Roger Ceilley of the University of Iowa, president of the
American Academy of Dermatology, said most of the people
getting melanoma now were exposed long before they began using
sunscreens.

"I personnally think it very likely reduces the risk of
melanoma," Ceilley said.  "I use it everyday and recommend it
to my patients."

Dr. Jouni Uitto of Thomas Jefferson University said most skin
specialists would agree.

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