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Application Note
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Fig. 1 Oriel Solar Simulators are widely used to verify skin product compliance with FDA, COLIPA and JCIA regulations. ****Caution - UV radiation has been found to be damaging to human skin and has been known to cause cancer. UV skin testing on live volunteers should only be performed by certified testing professionals.
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Researching the Effects of UV Radiation
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In recent years, there has been much debate over the effectiveness of sunscreens to filter UVA radiation and the long-term effect of unfiltered UVA radiation. Sunscreens do not block the UV radiation from reaching the skin, they assist the skin's ability to resist these effects. The sunscreen acts much like a filter in this process. UV radiation negatively affects the body's immune system. Until recently, UVA radiation was considered less of a contributor to skin cancers than UVB radiation. UVB exposure is the primary cause of sunburn on the skin while UVA exposure causes much less short-term visible effects. In more recent studies, evidence has suggested that the effect of UVA radiation may be as large a contributor to solar keratosis and subsequent squamous cell carcinoma, formerly attributed to UVB radiation.
Some research suggests that the UVA radiation penetrates the skin deeper and has more of a long-term effect than does short-term sunburn. UVA radiation can damage human DNA and is much more abundant in natural sunlight than UVB radiation. Because many sunscreens protect the user from UVB radiation more effectively than they protect from UVA, much more research is being undertaken to characterize the effects of UVA radiation and the ways to prevent its harmful effects.
Many sunscreen manufacturers are now testing their products to the "Broad-Spectrum" testing parameters, which include UVA wavelengths up to 370 nm. The AADA (American Academy of Dermatology Association) in an April 1, 2002 correspondence to the FDA suggested, "The in vitro critical wavelength method is a criterion for a broadspectrum claim. The threshold for this claim should be 370 nanometers (nm)."1
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1 AADA correspondence to the FDA, www.aadassociation.org/sunscreen.html
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