UV Skin Protection.

UV Skin Protection
Andre Willers
2 Nov 2011

“Can't live with them , can't live without them.” Pop-song , circa 20th century

Synopsis:
Optimal UV skin protection should allow only radiation of 295-297 nM to get to the skin to ensure Vit D3 production , and then only for about 30 minutes a day at midday in temperate regions .
Smart clothes with a nanostructure that is transparent at these wavelenghts is indicated .
Any other UV results in greater risks of DNA abnormalities (especially at 260 and 280 nM) or Folic acid destruction (especially at 290 and 360 nM)

Discussion:

0.Evolutionary Overview :

0.1Folic acid was first . It kept DNA/RNA structures stable . Note that the molecule contains only Oxygen , Hydrogen and Nitrogen atoms . A very early chaperone , even before the enrichment of the Earth's ecosphere with exotic metals from the Great Bombardment circa 3 Billion Years Ago .

0.2Vit D2 was next . Ergosterol(a membrane sterol) + UV → VitD2 . Ergosterol is only produced by fungi , phytoplankton , invertebrates . One of Gaia's major feedback stabilizing tricks .
See previous posts on non-angioforms .
http://andreswhy.blogspot.com : "Death of the Dinosaurs" Dec 2008

0.3Vit D3 was next :Calcium deposit regulation (bones and egg shells) .
“Dem bones , dem bones” Dem bones are just ambulatory eggs .

0.4Scales and Hairs(fine scales) evolved as a natural UVA shield .
VitD3 production was cleverly shifted to oils exposed to UV , ingested by grooming .
See below.

0.5When Humans lost most of their fur :
This is usually associated with the invention of clothes and the rise of fashion .
The prevention of the destruction of folic acid is much more important than the VitD formation .

But why keep such a vulnerable component so near the surface of the skin , where UV can get to it ? Because the skin is where the the rubber meets the tar . The skin erodes away fast , and it has to be replaced continually and quickly . For this the folic acid chaperone is essential . That is why even small spanners in the gears from UV here result in such malignant melanomas .

Clothes give double protection against folic acid destruction , as well as general melanomas .
And you could always take them off .

The result was heavy selection against body fur . Apart from the metabolic cost , it also formed host-niches for parasites like lice .
Exit body fur
Enter skin colours . See Appendix A(1)

Note the intriguing suggestion that the pale nordic skins evolved as a result of the invention of agriculture circa 6 000 – 10 000 years ago (some genetic evidence) . The logic is that hunter-gatherers could get enough VitD from their diet (like eskimo's) . Only when the preponderance of their diet shifted from hunting to farming , did a strong evolutionary pressure towards a lighter skin arise .

0.6Caffeine a hyper-apoptosis inducer ?

If true , this has major ramifications .
Caffeine + VitD3 + Folic Acid + VitD2 should then have great effect in ameliorating the damage caused by radiation (cancer therapy , sunburn , etc) . I put in VitD2 since I strongly suspect that it is very involved in the feedback processes .

It would also explain why caffeine (coffee , tea , colas , etc) are so popular .
There would be more healthy children , as sickly foetuses would spontaneously abort with greater frequency . This would lead to a population explosion . As was observed in the West or East where coffee or tea was consumed in large quantities . The poor man's genetic engineering .

But what is in it for the plant ?
Well , coffee is now the largest traded commodity after oil . A large part of of the planet's arable surface is devoted to coffee or tea . An evolutionary success

What is in it for humans ?
A drastic decrease in UV cancers (gives more farmers cultivating the plants ) , but also greater tolerances to environmental pollution . This on its own would significantly enhance large conurbations .
Steppe dwellers (Turks , Mongols , Tibetans , Afrikaners , etc ) were all subject to high UV radiation , and all (without exception) , used caffeine if available .
We can even go so far as to say that the high-UV areas would be non-viable for human habitation if it were not for the hyper-apoptosis gene-editing of caffeine .

See
http://en.wikipedia.org/wiki/Sunscreen
Recent evidence indicates that caffeine and caffeine sodium benzoate increase UVB-inducedapoptosis both in topical and oral applications. In mice, UVB-induced hyperplasia was greatly reduced with administration of these substances. Although studies in humans remain untested, caffeine and caffeine sodium benzoate may be novel inhibitors of skin cancer.[67]

0.6Birds , Chickens and Caffeine .
Successful pathogens would be focussed via preening mechanisms if they have access to human caffeine middens (coffee grounds , tea bags , etc) . Instead of of declining in well-known ways , the pathological agents' genetic drift is slowed or halted by the caffeine induced apoptosis of mutants .
This would have significant epidemiological effects , not catered for in present models .

0.7Summary .
Sunscreens or sunblockers used for more than 20 minutes seems to be more risky than clothing and a moisterizer like olive oil . This risk can be ameliorated to an unknown degree by caffeine intake .

A note of caution : VitD2 seems to be associated with the major Gaiean non-angiosperm feedback system . It has to be taken into account .

0.8Sources :
I have put the sources in Appendix A .
Best is to read the links .

“Don't put your daughter in the Sunspot , Mrs Worthington.” With apologies to Noel Coward .
Andre .

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Appendix A
1.General Skin-color overview :
http://anthro.palomar.edu/adapt/adapt_4.htm

http://en.wikipedia.org/wiki/Human_skin_color

2.Folic Acid
http://en.wikipedia.org/wiki/Folic_acid
Vitamin B9 (folic acid and folate inclusive) is essential to numerous bodily functions. The human body needs folate to synthesize DNA, repair DNA, and methylate DNA as well as to act as a cofactor in biological reactions involving folate.[7] It is especially important in aiding rapidcell division and growth,

http://www.edoj.org.eg/vol002/00201/13/paper.pdf
B randa and Eaton [5]
previously reported that exposure of human plasma in vitro to solarsimulated radiation causes 30-50% loss of folate within 60 minutes. In
vitro studies have also shown that various folate vitamers
(polyglutamates) may be detected using fluorescence detection at UV
excitation of different wavelength, e.g. 290 nm or 360 nm[13]

3.Vitamin D
http://en.wikipedia.org/wiki/Vitamin_D
In humans vitamin D is unique both because it functions as aprohormone and the body can synthesize it (as vitamin D3) when sun exposure is adequate.
Cholecalciferol (Vit D3) is produced photochemically in the skin from 7-dehydrocholesterol; 7-dehydrocholesterol is produced in relatively large quantities in the skin of most vertebrate animals, including humans.[13] The naked mole rat appears to be naturally cholecalciferol deficient, as serum 25-OH vitamin D levels are undetectable.[14] In some animals, the presence of fur or feathers blocks the UV rays from reaching the skin. In birds and fur-bearing mammals, vitamin D is generated from the oily secretions of the skin deposited onto the feathers or fur and is obtained orally during grooming.[15]

4.General UV absorption
http://www.jstor.org/pss/3575456
Abstract
Although DNA absorption at wavelengths greater than 300 nm is much weaker than that at shorter wavelengths, this absorption seems to be responsible for much of the biological damage caused by solar radiation of wavelengths less than 320 nm. Accurate measurement of the absorption spectrum of DNA above 300 nm is complicated by turbidity characteristic of concentrated solutions of DNA. We have measured the absorption spectra of DNA from calf thymus, Clostridium perfringens, Escherichia coli, Micrococcus luteus, salmon testis, and human placenta using procedures which separate optical density due to true absorption from that due to turbidity. Above 300 nm, the relative absorption of DNA increases as a function of guanine-cytosine content, presumably because the absorption of guanine is much greater than the absorption of adenine at these wavelengths. This result suggests that the photophysical processes which follow absorption of a long-wavelength photon may, on the average, differ from those induced by shorter-wavelength photons. It may also explain the lower quantum yield for the killing of cells by wavelengths above 300 nm compared to that by shorter wavelengths.


5.UV Screens
http://en.wikipedia.org/wiki/Sunscreen
Some sunscreen chemicals produce potentially harmful substances if they are illuminated while in contact with living cells.[27][28][29] The amount of sunscreen which penetrates through the stratum corneum may or may not be large enough to cause damage. In one study of sunscreens, the authors write:
The question whether UV filters acts on or in the skin has so far not been fully answered. Despite the fact that an answer would be a key to improve formulations of sun protection products, many publications carefully avoid addressing this question.[30]
In an experiment by Hanson et al. that was published in 2006, the amount of harmful reactive oxygen species was measured in untreated and in sunscreen-treated skin. In the first 20 minutes the film of sunscreen had a protective effect and the number of ROS species was smaller. After 60 minutes, however, the amount of absorbed sunscreen was so high that the amount of ROS was higher in the sunscreen-treated skin than in the untreated skin.[6]
Some epidemiological studies indicate an increased risk of malignant melanoma for the sunscreen user.[32][33][34][35][36][37][38][39] Despite these studies, no medical association has published recommendations to not use sunblock. Different meta-analysis publications have concluded that the evidence is not yet sufficient to claim a positive correlation between sunscreen use and malignant melanoma.[40][41]


The use of sunscreen also interferes with vitamin D production, leading to deficiency in Australia after a government campaign to increase sunscreen use.[44] Doctors recommend spending small amounts of time in the sun without sun protection to ensure adequate production of vitamin D.[45] When the UV index is greater than 3 (which occurs daily within the tropics and daily during the spring and summer seasons in temperate regions) adequate amounts of vitamin D3 can be made in the skin after only ten to fifteen minutes of sun exposure at least two times per week to the face, arms, hands, or back without sunscreen. With longer exposure to UVB rays, an equilibrium is achieved in the skin, and the vitamin simply degrades as fast as it is generated.[46]


For those who choose to tan, some dermatologists recommend the following preventative measures:
Sunscreens should block both UVA and UVB rays. These are called broad-spectrum sunscreens, which should also be hypoallergenic and noncomedogenic so it doesn't cause a rash or clog the pores, which can cause acne.
Sunscreens need to be applied thickly enough to get the full SPF protection.
Sunscreens should be applied 15 to 30 minutes before exposure, followed by one reapplication 15 to 30 minutes after the sun exposure begins. Further reapplication is only necessary after activities such as swimming, sweating, and rubbing.[65]
Sun rays are strongest between 10 am and 4 pm.[66] Sun rays are stronger at higher elevations(mountains) and latitudes near the equator.
Wearing a hat with a brim and anti-UV sunglasses can provide almost 100% protection against ultraviolet radiation entering the eyes.
Reflective surfaces like snow and water can greatly increase the amount of UV radiation to which the skin is exposed.
Recent evidence indicates that caffeine and caffeine sodium benzoate increase UVB-inducedapoptosis both in topical and oral applications. In mice, UVB-induced hyperplasia was greatly reduced with administration of these substances. Although studies in humans remain untested, caffeine and caffeine sodium benzoate may be novel inhibitors of skin cancer.[67]
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