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Author Topic: Sun Protection Factors, double trouble.
skeptic
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Is it true that SPF 30 will literally give twice the protection as SPF 15, or 20 is twice as good as 10.
Wikipedia states,
quote:
(SPF) an indication of how long a sunscreen remains effective when applied to the skin
Example: If someone normally burns in 10 minutes with no sunscreen, then a sunscreen with factor 20 will provide protection for up to 20x10 = 200 minutes

(Yes, I know Wiki is not 100 pc reliable, but they are quoting what I have heard a million times).
Isn't there some sort of diminishing return involved. I think Australia limits the SPF factor to 15+ to avoid false claims.
Any sunburnt scientists out there???

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Ieuan ab Arthur
The First USA Noel


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Hi Skeptic:

That's the story that I've always heard (i.e., natural sun burn resistance given the conditions * SP factor). I doubt it is that simple. For example, it sort of assumes that until you reach the calculated minute, you're fine. However, at the designated minute, you're wide open. I imagine that it would be more the case that the higher the SPF factor, the lower the UV ray penetration would be. I simply use the SPF factor of the relative "strength" of the protection.

As the old commercial goes, I'm not a doctor. However, I'm willing to give some totally worthless and untrustworthy anecdotal evidence on the subject:

I have very light skin and I burn easily. I use an SPF 45 sunblock when playing golf. I can be out on the course for six hours in high UV conditions and not burn. However, over the course of a summer, I do get a bit of a tan.

Take that for what you will - YMMV.

Ta ra 'wan,

Ieuan "golden brown" ab Arthur

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ILS
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On a slightly different note.

I once heard that the developer of the SPF scale created by defination SPF 30 to be 100% sun block/protection. (Similar to the Celisus scale which sets 100 degrees by defination to be the tempeture of boiling water at sea level.)

If true, makes anything higher to be a bit silly.

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tresequis
I'm Dreaming of a White Sale


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That's the way SPF is supposed to work, yeah. But some people falsely believe it refers to hours of protection, i.e. SPF = 1 hour, etc. That, of course, would completely ignore differences in sun strength and skin sensitivity, which is why it's called sun protection FACTOR.

Bud Light runs radio ads called "Real Men of Genius" that mock stupid people. One of them makes fun of people who use SPF 30 sunscreen, because after all there are only 24 hours in a day. Well, they're the "geniuses." There's nothing dumber than making fun of someone else's stupidity based on your own. Which explains people like, say, Ann Coulter.

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RichardM
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As someone with very fair skin, I have found a very good product. It does not have an SPF rating but it protects all day. The brand name is 'Liquid Paper'. Another similar product is "White Out'.
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Starla
It Came Upon a Midnight Clearance


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Sunscreen may not be as effective as we have been lead to believe.
quote:
But in the wake of a class action lawsuit filed recently in California against sunscreen manufacturers - claiming they have fraudulently exaggerated the effectiveness of their products - Baus has started to wonder.

In fact, although dermatologists still recommend the liberal use of sunscreen, they warn that it's entirely possible for the sun to damage skin without burning it, and that most of the sunscreens currently on the market do a better job preventing sunburn than they do at preventing other problems - including premature wrinkles, age spots and even skin cancer.

As for what SPF means
quote:
Sun Protection Factor (SPF) - the number tells you the amount of time it will take your skin to burn with sunscreen compared to the amount of time before you'd burn with no sunscreen. (In other words, an SPF of 8 means you can stay in the sun 8 times as long as you could with no protection on your skin before your skin begins to burn.)

In order to find out how long SPF 30 would keep you from getting burned you'd have to find out what the UV Index was for the day. My local news station reports the UV index with the weather and it's something like, "today's UV index is Blank. The average person can stay in the sun for 15 minutes unprotected before starting to burn."

I don't know anyone who would sit down and do the math, so using a high SPF is best, but some days the sun is more intense than others. So some days you could wear SPF 30 all day and not burn, but other days you might burn.

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00-Saleen
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I, too, am extremly fair-skinned. I work outside, in TX, all year, 8-16 hrs a day. I slather on the 35 & above, wear a hat, and stay in the shade as much as possible. I haven't had a sunburn yet (Xs fingers, knocks on wood). I got some bad burns as a kid, which I've heard is one of the biggest contributors to later skin cancer. I've had one pre-cancerous spot removed--which is covered by my pants and boots and rarely, if ever, sees the sun.

My dermatologist said (IIRC) that there aren't enough "burnable hours in the day" for any SPF above 30-40. So pick the SPF that's right for your skin type and that you like, and have at it. I like the oil-free, waterproof, sweatproof ones--Ocean Potion and Aveeno right now.

I think that Bud Light commercial is hilarious though. "Mr. 80 SPF Sunblock Wearer Guy" That's me and the SO [Big Grin] [Razz]

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snopes
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Sunscreen is evolving, but many basics remain the same

If you've cruised the sunscreen aisle at the grocery or drugstore lately, you know the choices seem almost endless. Spray, cream or nongreasy lotion? SPF 15, 45 or something in between?

Now factor in this season's new offerings — a sunscreen ingredient called Helioplex and a new sunscreen pill — and recent class-action lawsuits charging that the sunscreen makers have inflated the protective qualities of their produc

http://www.latimes.com/travel/la-tr-healthy21may21,1,3875763.column

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timbobmc
Jingle Bell Hock


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snopes,

In our litigious society, the concept of personal responsibility has died. What I finally came to understand is that it doesn't matter what the SPF factor of the sunscreen is, if you don't reapply it every hour and a half to two hours, you're going to get burned.

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snopes
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Do Your Skin a Favor: Protect It in Summer

More myths than facts abound about sunscreens. And more people misuse them than use them properly.

First, there is no evidence that the use of sunscreen increases the incidence of skin cancer. Nor is there evidence that regular use of sunscreens can cause internal damage. These are surface agents only; they don't get inside cells or penetrate deep into the skin.

True, sunscreens reduce the body's ability to form vitamin D. About 15 minutes of sun a day in summer on unprotected face and arms can result in a year's supply in people under 65. But at any age, this essential nutrient is more safely obtained from foods and vitamin supplements.

Most sunscreens protect against both ultraviolet B radiation, which causes sunburns, and ultraviolet A radiation, which ages the skin. Both types have been implicated in skin cancer. But the S.P.F. rating (for sun protection factor) relates only to UVB exposure.

If a person who would get sunburned without protection in 20 minutes uses a product with an S.P.F. of 10, that burn should not occur until spending 200 minutes in the sun, assuming the sunscreen is slathered on properly.

http://www.nytimes.com/2006/06/06/health/06brod.html

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abigsmurf
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There was a study in the UK a few years back that found that suntan lotion and aftersun was actually better for your skin than expensive skin cream. Turns out the vitamin D as well as the stuff to stop the skin drying out does all sorts of wonders if used when not in the sun.

But with high factor suntan lotion, you'll sweat it off long before it's effectiveness wears off, those lawsuits are directly caused by people just not paying attention to advice that's been printed on bottles for at least 15 years.

most people who get badly burnt are either burnt through their thin shirts or from spots they missed with suntan lotions. Football shorts are especially bad at keeping the sun out and amusingly if someones sunbathed wearing a football shirt, they'll likely have the shirt sponsors name stenciled on their chests.

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Neffti Noel
We Three Blings


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quote:
Originally posted by abigsmurf:
There was a study in the UK a few years back that found that suntan lotion and aftersun was actually better for your skin than expensive skin cream. Turns out the vitamin D as well as the stuff to stop the skin drying out does all sorts of wonders if used when not in the sun.

Hi Abigsmurf,

I didn't read that article but I thought that the reason people using suncream got a good fix of Vitamin D was due to their exposing themselves to sunlight, rather than absorbing something from the suncream itself? I doubt that the body can produce Vitamin D by suncream alone.

I would be interested to read the article though. Anything to make me feel less "unwomanly" for not spending £20+ on skincare products is most welcome [Big Grin]

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snopes
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Here comes the sun debate

Sun exposure can cause cancer. Sun exposure might prevent cancer.

People who wear sunscreen probably lower their risk of skin cancer and wrinkles. People who wear sunscreen remain at risk for skin cancer and wrinkles.

All of the above statements are true, and some have received wide publicity. The mixed message worries skin doctors.

http://www.usatoday.com/news/health/2006-05-07-your-health-sun_x.htm

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PrincessLeia
I'll Be Home for After Christmas Sales


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And there is this link.
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