Sun Screen

Do you know what is SPF mean? Do you know much amount we should apply to protect our skin? Here are answers:
The FDA has defined SPF as the amount of time it takes to produce minimal redness(erythema) in skin via UVB exposure. This is called the Minimal Erythemal Dose(MED), and its achieved when the skin attains the amount of UVB required to produce redness ,more commonly known as sunburn.
An SPF 2 enables the skin to be exposed to UVB twice as long as when sunscreen is not used before the MED is attained. This means that an SPF2 absorbs 50% of UV rays, allowing the other 50% to get through, so it takes twice as long for the skin to absorb the amount of UV needed to produce redness.An SPF 8 absorbs 87.5% of the rays. Leaving 12.5% to reach the skin. An SPF 15 absorbs 93.33%, allowing 6.67% UV to get through and SPF 30 absorb 96.67% allowing 3.33% to pass . Now you see that even the higher SPF will not absorb 100% of UV rays. This is why the FDA no longer allows the use of the term “Sun Block” to describe sunscreen.
SPF 30 does not offer twice the protection as an SPF 15
Based on thenumbers, SPF 30 offers less than 4% more protection than an SPF15 But that is not the whole story. To achieve the extra 4% the higher SPF must reach beyond UBV rays into the UVA part of the part of the sun’s radiant spectrum. Because UVA is implicated in phototoxic and pthotoallergic reactions, as well as diseases such as lupus, this extra 4% can be enough to keep certain complexions safe in the sun.
*****Sunscreen are over-the counter(OTC) drugs that are regulated by the FDA.
Many company claim their natural ingredients has UV protection effect, however It can not be identified as sun screen. The only exception is if the product , not the individual ingredient receives New Drug approval from FDA
Following ingredients are recognized by FDA as sunscreen in these OTC drugs.
AminobenzoicAcid(PABA), Avobenzone, Cinoxate, Dioxbenzone,
From Skin Inc magazine

2010.09.06 | | Comments(0) | Trackbacks(0) | cosmetic ingredients


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