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Abundant research exists showing the need to protect
skin from the sun's UVA rays (Sources: Photochemistry
and Photobiology Science, August 2004, pages 736-740 and
Cutis, September 2003, pages 11-15). The only three ingredients
approved by the FDA that can protect skin from UVA damage
are avobenzone, titanium dioxide, and zinc oxide.* (Outside
of the US, Tinosorb and Mexoryl SX are also UVA-protecting
ingredients.) It is critical that one of these ingredients
appear in the active ingredient list of any sunscreen
(Sources: Journal of the American Academy of Dermatology,
December 2000, pages 1024-1035; Photodermatology, Photoimmunology,
and Photomedicine, December 2000, pages 250-255; British
Journal of Dermatology, August 1999, pages 250-258.)
Despite the research showing these ingredients as fundamental
to a sunscreen's ability to protect skin, nagging questions
about avobenzone's stability persist. This uncertainty
resulted from a story that appeared in Health magazine
(May/June 1998) reporting on research conducted by Robert
Sayre, a physicist in photobiology at the University of
Memphis, suggesting that avobenzone may break down in
as little as 30 minutes when exposed to sunlight.
Sayre's study, which was never published or peer reviewed,
(Source: Cosmetics & Toiletries, November 1999, pages
84-90) caused a commotion in the cosmetics industry. If
Sayre was right (he wasn't, but I'll get into that in
a second), a lot of sunscreen products should have been
thrown in the garbage. Unfortunately, Health magazine
did not look into how Sayre came up with his findings;
his work was done only in a petri dish and not on human
skin and he used far less than the amount required by
the FDA for sunscreen testing. Even more significantly,
there are still no other studies substantiating Sayre's
results anywhere in the cosmetics or medical world.
It is critical for consumers to know that avobenzone
is not some untested or untried sunscreen agent.
It has been around since 1981 and is one of the most widely
used sunscreen ingredients in the world. It is also the
No. 1 sunscreen agent in Canadian, Australian, and European
sunscreen formulations. The FDA approved avobenzone's
use as a sunscreen agent in the United States after more
than seven years of study. Avobenzone had to meet scrupulous
performance standards when Hoffman LaRoche applied for
it to receive new drug status from the FDA. New drug status
is the most stringent FDA classification and requires
more safety studies and efficacy substantiation than you
can imagine. Avobenzone held up under all of the FDA's
safety and potency protocol, or it wouldn't have been
approved (www.fda.gov, Federal Register 1999: 64: 27666-27963.)
Even more significant, the January 1996 issue of Journal
of Chromatography BioMedical Applications contained a
study that looked at the issue of sunscreens degrading
when exposed to sunlight. Their conclusion for avobenzone
was as follows: "After 72 hours Parsol 1789 [avobenzone]
in the sample exposed to the sun was decreased by up to
25% of the initial concentration." That 25% decrease
was after 72 hours (far longer than anyone is supposed
to rely on a sunscreen) and is a far cry from the 50%
decrease reported by Sayre after only 30 minutes.
The definitive answer to the question about whether or
not avobenzone is a stable sunscreen ingredient is that
it is absolutely stable and there is substantial research
showing that to be the case. (Sources: Journal of Investigative
Dermatology, October 2003, pages 869-875; Journal of Cosmetic
Science, November/December 2003, 589-598; Photodermatology,
Photoimmunology, and Photomedicine, August 2003, pages
190-194 and August, 2000, pages 147-155; Photochemistry
and Photobiology, February 2002, pages 122-125; Internet
Photochemistry and Photobiology, www.photobiology.com/photobiology99/contrib/finlay/;
and The Journal of Investigative Dermatology, August 2001,
pages 256-267).
Avobenzone has value because it is one of only three
active sunscreen ingredients available in the United States
that protect skin from the entire UVA spectrum (the other
two are titanium dioxide and zinc oxide). Without avobenzone,
U.S. sunscreen options would be narrow indeed, and unless
you have a known allergy to it, there is absolutely no
reason to avoid avobenzone when shopping for effective,
broad-spectrum sunscreens.
*Avobenzone may appear on labels as butyl methoxydibenzoylmethane
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