36% Baseline (Pre -Irradiation): Critical Wavelength
Pre-Irradiation 1 MED 2 MEDs 379.
For UVA, Consumer Reports con ducted a critical wavelength
test similar to what the Food and Drug Administration requires of manufacturers.
We plot the R and T in the wavelength domain (from 100-1200 nm) from which a 50/50 BS can be obtained at a critical wavelength
To earn the seal a product must have UVB protection of SPF 15, UVA protection with a critical wavelength
score of 370 or a persistent pigment darkening (PPD) score of 5, and proof of photostability.
DeLeo explained that there is no way to know the degree of UVA protection offered by sunscreens marketed in the United States, unlike in Europe, where products are tested for efficacy and photostability according to critical wavelength
, an in vitro assessment, and the persistent pigment darkening method.
Since some metals may hold electrons more firmly than others, the critical wavelength
must be shorter in some cases than in others.
We analyzed the six formulations containing bemotrizinole and bisoctrizole for stability, critical wavelength
(broad spectrum protection criteria) and SPF testing (two subject in-vivo).
The latter should be assessed using an in vitro critical wavelength
method, and an in vivo persistent pigment darkening (PPD) method, Dr.
The ruling also allows the use of multiport solar simulators for SPF testing, reduces test panel size from 20 to 10 for SPF testing, and relies on critical wavelength
test methods for "broad spectrum" claims and not the UVA1/UV ratio test.
The US FDA's release in 2011 of a final rule on sunscreen caused a major uptick in requests to test UVA critical wavelength