Wednesday, April 18, 2012

The Popular Mechanics of Sun Exposure

While it’s interesting to see which key word searches led people to my blog, it’s equally interesting to see where else those same words lead me.  Today I followed the key words “sunburn time chart.”  There were a few sites regarding the UV Index, but one site in particular seemed like the obvious choice for all things sunburn related.

Popular Mechanics.

The article is called “Anatomy of a Sunburn: A Timeline ofDermatological Destruction.  It breaks down the details of the sunburning process within the skin in fairly layman terms.  Feel free to read the article yourself, but here’s a summary of the more interesting points.

Some of the warmth you feel as you step into the sun is literally the absorption and conversion of UV rays to heat by the melanin.

As you’re exposed to the sunlight and UV rays, the melanin goes on the defensive and spreads itself around to cover the cell nuclei where the DNA resides.  But for lighter skin folks, there’s simply not enough melanin to go around. (Note…darker skin people can have gaps in their melanin coverage as well, so they also need sunscreen).

When there’s no melanin, the UVB rays sneak in and cause INSTANT damage to the DNA cells.  As one spokesperson from the Skin Cancer Foundation stated, “the nice spiral staircase (of DNA) is knocked off-kilter.”

As the DNA gets damaged, the blood vessels dilate in the dermis (the layer below the epidermis) to nourish the outer layer of skin.  Meanwhile, the melanocytes that are located in the basal layer of the epidermis are working overtime to develop more pigment for protection.  Well, not really overtime because it takes anywhere from one day to three days for these pigments to deploy (explaining why skin “tans” after the burn).

So essentially, the tan is a sign that the body is trying to repair damaged skin and DNA…or in other words, a tan is a sign of bodily harm…NOT a “good” thing at all.

As one roasts longer in the sun, the DNA damage gets more extensive and deeper.  Cells on the outer layer (epidermis) are self-programmed to die and peel away.  But those cells deeper in the skin cannot shed or peel.  Enzymes can repair most of the DNA damage, but the occasional spot gets missed and leads to mutations.  This is how basal cell and squamous cell carcinomas are formed.

In extreme sunburning, second degree burns can result.  These burns are the same as if you stuck your hand on a hot iron…it is heat and seared flesh.  Blisters form and separate the dermis from the epidermis.  Such blisters are a risk factor for developing melanoma.  (Note that this is not the only cause of melanoma, just the only one mentioned in the article).

Eventually keratinocyte cells are created in the basal layer and migrate to the outer surface.  This in turn causes the attractive massive peeling process.  And in many foolish cases, the process is repeated every season if not more often.

I found that understanding the DNA damage and the body's attempt to repair itself fascinating.  It only stands to reason that if one subjects himself to such a cycle over and over, serious, cancerous damage could result.

If you take nothing else away from this posting or the related article, remember the one line. 

Though suntans are seen as attractive, actually they are signs of bodily harm!

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