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UVA Protection
of Sunscreen
Lim, Henry1
Department of Dermatology, Henry Ford Health System, Detroit, Michigan,
USA1
Abstract-
The US Food and Drug Administration released its final sunscreen monograph
in May, 1999, to be fully implemented by December 31, 2002. The monograph
listed 16 UV filters as approved agents; newly approved agents were
avobenzone (Parsol 1789) and zinc oxide. It also specified the testing
methods for determination of sun protection factor (SPF) and water resistance.
Maximum SPF was to be 30+. The use of several terminologies (e.g., "sunblock,"
"anti-aging,"
"non-chemical,"
and "chemical-free")
were addressed. However, sunscreen UVA protection was addressed with
far less specificity. A consensus conference on this issue was held
in 2000, sponsored by the American Academy of Dermatology; invited attendees
included representatives from the FDA, EPA, industry, ASP, and other
photobiology organizations. The following UVA protection issues were
discussed: 1. In vivo methods: immediate pigment darkening (IPD),
persistent pigment darkening (PPD), and UVA erythema protection factor
(PFA); 2. In vitro method: critical wavelength; and 3. Labeling
of sunscreens. In addition, photobiologists from the Great Britain,
Australia, Germany, and Austria presented methods used in their respective
country. The followings are the recommendations of the conference: 1.
SPF is the primary consideration for sunscreen potency; 2. Broad spectrum
sunscreens need to pass an in vitro test (critical wavelength of 370
nm or greater) and an in vivo test (PPD or PFA, with at least a 4-fold
increase in protection); 3. Once the above criteria have been achieved,
sunscreen would be labeled simply as "broad
spectrum", therefore minimizing
confusion to the consumers.
Keywords: sunscreen,
UVA, pigment darkening, critical wavelength
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