UV information

So I was reading about UV radiation in my books, and a lot of this stuff I did not know about, so I have decided to share it with you guys.

First of all, I think all you guys know that there are 2 types of radiation, UVA and UVB. UVA is the one that can go deep in the skin, and cause all that fun stuff like photoaging (massive wrinkling, breakdown of your elastic fibers, and yellowing/thickening of the skin). UVB is the one that goes into the epidermis but no deeper.

BOTH UVA and UVB can cause DNA damage leading to basal cell carcinoma, squamous cell carcinoma, both types (malignant and benign) melanoma, and actinic keratoses.

UVA can penetrate glass, UVB cannot.

There is no clear evidence that sunscreen protects against melanoma or basal cell carcinoma!

So, the big question is now...how do you save yourself from UV rays?

There are 2 types of of sunscreens, organic and inorganic. Organic sunscreens absorb UV radiation and then disperses it as heat while Inorganic sunscreens act as a barrier by scattering the radiation before absorption into the skin.

If you buy an organic sunscreen, it has to contain a large mixture of compounds in order to be effective against the UV spectrum. However, it MUST CONTAIN avobenzone or the product is basically dysfunctional. The only products on the market that have this compound in it are Aveeno (continuous protection), Neutrogena (ultra sheer dry-touch), Coppertone (sport), and Sea & Ski.(advanced sunscreen).

If you buy an inorganic sunscreen, it HAS TO CONTAIN titanium dioxide AND zinc oxide in order to be effective.

Ok, so now some info about the SPF factor. SPF is like an indicator of the protection of radiation from UVB only. It does not include information about protection from UVA rays. SPF is basically determined by shining UV light on someone's skin on a protected area (with sunscreen) and on an unprotected area (without sunscreen). Then the time starts ticking. The time is stopped per area when redness of the skin is noted. For example, if your skin gets red after 10 min w/o sunscreen, and your skin gets red (on the other part) with sunscreen after 150 minutes, then you would divide 150/10 =15. So the SPF of that sunscreen would be 15. So you can see, SPF is not precisely analyzed. Since the methods are so diverse that companies use to determine the SPF, products with the same SPF do not provide equal levels of protections!

Also about SPF. SPF and amount of protection do not have a linear relationship. What I mean by this is, SPF of 30 does not provide twice as much protection as an SPF of 15. Instead, if you really want to know, as SPF increases, the increment of protection decreases. For example, SPF 15 specifies 93% block of UVB, while SPF 30 specifies 97%, and SPF 40 indicates 98%. 

More about sunscreen...and the water/sweat resistance:

If a sunscreen advertises for water resistant, it means that it must retain its SPF for at least 40 minutes of water activity. If a sunscreen says it's very water resistant, it means that it has to retain its SPF for at least 80 minutes of water activity.

Why don't they tell us these things?!


*Infomation obtained from Pharmacology for Nursing Care, by Richard Leyne, 7th Edition