Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: MayoFlyFarmer on 05/01/2008 18:53:42
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I have a question for any of you who know anything about dermatology, or are expert tanners. I thought I knew the difference between UV-a and UV-b rays but recently i've seen some information that contradics what I thought to be correct. (Since I got this information when I was a teenager and the dermatologist came to lecture us life guards, I may remember it incorrectly, or there may be new information out since then)
My understanding was that UV-a burns you, and UV-b tans you. Thus UV-a is bad for your skin, and UV-b produces the Mellin that protects you from the UV-a. I had thought that the sun as well as conventional tanning beds contain both a&b, and that the new "ultra-bronze" beds only use UV-b.
Recently I was told that UV-b is actually what burns you AND causes mellin production, and that UV-a only darkens the Mellin that is already in your skin by oxidizing it. They said that "ultra-bronze" tanning beds only have UV-a; so while they give you the best LOOKING tan with the least amount of burning, they do not actually produce any new Mellin for you and thus give you no natural protection from the sun.
Another person actually told me that Mellin doesn't actually protect you from the sun at all, its just a big myth. I really don't believe that because i thought that was the whole biological role of Mellin; but i guess they could be right.
I am going on a carribean cruise in the middle of the winter next week, and (while i don't ordinarilly use tanning beds) i wanted to do a little bit of tanning before I go, so that I don't FRY as soon as I get down there becaue that 1) is horrible for your skin and 2) makes for a misserable vacation.
Any info anyone could give me on this subjct to clear it up would be much appreciated!
Thanks
-J
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Try this (http://www.thenakedscientists.com/forum/index.php?topic=350.msg8924#msg8924)by chris.
These may also be worth a read
http://www.thenakedscientists.com/forum/index.php?topic=7809.0
http://www.thenakedscientists.com/forum/index.php?topic=9703.0
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Just ask for some Vampire Factor sunblock, that should do the trick.
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thanks for the reply paul; is there a first link that you meant to include, but left out of that post???
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thanks for the reply paul; is there a first link that you meant to include, but left out of that post???
The word 'this' is hyperlinked, any way, this is this link
http://www.thenakedscientists.com/forum/index.php?topic=350.msg8924#msg8924
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thanks paul. sorry, i missed that hyperlink when i read your post.
anyone have any info about the difference between effects of UV-alpha and UV-beta and which type is used in different types of tanning beds?
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My understanding has always been that the UV-A was allegedly "safer", while the UV-B was more responsible for burning. I have also heard that the tan you get from UV-A-only exposure provides rather less protection from subsequent radiation than a tan resulting from natural unfiltered exposure. How reliable this information is, I don't know.
I have seen people with a very peculiar orangey-tan, which they assure me is "natural" but fades after a few weeks, and which I suspect may be caused by very potent UV-A-passing, UV-B blocking suncreams...?
Regardless, a tan sufficient to provide any significant protection is aquired only by a large number of modest exposures to UV. I think it is wishful thinking to hope that a couple of bursts on a sun-bed in under a week will offer any meaningful protection.
Remember the sun's UV strength varies almost sinusoidally with the time of day, reaching a peak at solar midday, and zero at sunrise/sunset. In the four hours in the middle of the day, (10-2, or 11-3 depending on the local time) you will get something like 60% of the total whole-day (sunrise to sunset) dose of UV. Keep indoors or under a large canopy at that time, and you will do a lot to moderate your exposure.
See also this research paper which quite hard-core, but has loads of great information:
http://users.ntua.gr/mmakro/UVsource-measurem.pdf
I always chuckle when I see folks applying sunscreen at 6pm on Brighton beach at in the summer. By that time, either they don't need it, or the damage is already done!
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thanks paul. sorry, i missed that hyperlink when i read your post.
anyone have any info about the difference between effects of UV-alpha and UV-beta and which type is used in different types of tanning beds?
Sun tanning bed is a device emitting ultraviolet radiation (typically 97% UVA and 3% UVB) used to produce a cosmetic tan. Most tanning beds emit mainly UVA rays which may increase the risk of melanoma, the deadliest form of skin cancer.
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Tanning beds (and tanning in general)- further proof against white supremacy and that there is a sucker born every minute.
What ever happened to the alabaster complexion as a beauty goal? My grandmother would have looked on today's tanned people as a bunch of field hands and [rude word for people from the Mediterranean]and made them come to the back door.
Ms. Martinthek is a fair colleen who grew up on the beach in Santa Cruz where as a teenager she avidly pursued the ideal tan. Nowadays as a Grandmother those chickens have sadly come home to roost.