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Skin Care and Diseases

What does UV light mean to me?

06/28/2006

Question:

I keep reading about ultraviolet or "UV" light. I am concerned about skin cancer, because my sister and dad have it, and I have read that UV light can cause this, but I don`t really understand how to avoid it. Also, is it what we call "black lights"?

Answer:

The solar radiation reaches the earth as a continuous electromagnetic spectrum.  Approximately 230 nanometers of radiate energy is filtered out by our atmosphere and protects us from very short wavelengths that approach x-ray in strength.  The other end of the spectrum contains a number of wavelengths, and our eyes pick up many of the wavelengths in the visible spectrum.  Those are characterized by the colors of the rainbow.  In addition, heat energy is transmitted, forming the far end of the electromagnetic spectrum. Ultraviolet light B is in that spectrum from about 230 to 320 nanometers.  It is quite biologically active and exposure to it can produce changes in the structure and function of all elements of the skin.  Ultraviolet light A is a slightly longer wavelength that runs through the serrate band of 440 nanometers.  Both ultraviolet light A & B are biologically active; ultraviolet light B is primarily responsible for intrinsic (that is within the skin) production of vitamin D and is important in controlling the integrity of the immune system and the production of intrinsic vitamin D.  Despite the beneficial effects of the shorter wavelengths of light, prolonged exposure and extensive exposure produces damage to the connective tissue, as well as the epithelium, and the appendages of the skin. 

Is this long term damage that may result into the development of skin cancer in the form of basal cell carcinoma, squamous cell carcinoma, and malignant melanoma?  The position of us in dermatology is that we should protect you from excessive ultraviolet light exposure through protective clothing and sunscreens.  We urge you to use them!   

I would suggest that you purchase light protective sports clothing, available at most sporting goods establishments, and use a sunscreen with a sun protective factor (SPF #) of 30 or greater.  Redness means injury.  Rapid darkening is part of the reaction of the pigment cells to light injury.  Try to avoid these.

"Black Lights" are ultraviolet light, and in most cases are in the UVA spectrum.  They produce interesting fluorescence of certain dyes and body fluids.  Ultraviolet light A certainly can accelerate aging of the retina in the eye.  Prolonged exposure can also lead to premature aging of the skin and malignancy. 

If you are interested in reviewing ultraviolet light extensively I would suggest the website of the American Academy of Dermatology (www.aad.com).  Look under light and photobiology.  I think you will find a number of interesting references.  Please check the website.

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Response by:

Charles L Heaton, MD
Professor
College of Medicine
University of Cincinnati