SAFETY NOTICE on Sunburn and Skin Cancer (Melanoma)
Sunburns and tans are caused by exposure of the skin to the sun's ultraviolet (UV) rays. Three ranges of wavelength are distinguished by most scientists, and they are in decreasing order of wavelength and increasing order of energy UVA (320-400 nm); UVB (280-320) and UVC (less tan 280 nm). UVC is totally blocked by the atmosphere by ozone but UVB and UVA are not. UVB causes sunburn and all sunscreens protect against this range of wavelengths. Recent evidence suggests that UVA also causes skin cancer and many sunscreens do not protect against this range of wavelengths unless specifically indicated on the bottle. As a result there is a higher incidence of melanoma even with people who use sunscreens. It is essential that all personnel who do extended field work (or outdoor recreation) use proper clothing and sunscreen to prevent sunburns and excessive tanning. Sunburns are a long-term cumulative problem rather than a short-term problem since the skin's DNA becomes damaged and gene damage can result. A little known fact is that the UV-VIS spectrum of ozone (O3) is identical to DNA! Since there are significant areas of the world's atmosphere which are ozone depleted, it becomes a necessity to have proper clothing and sunscreen protection at these areas.
Skin cancer (if left undiagnosed spreads into the bloodstream and lymph nodes) is one of the deadliest and fastest spreading forms of cancer. In other words, don't take this alert lightly. The author has just been diagnosed of skin cancer at the earliest stage (#1; there are 4 clinical stages ) and been treated successfully by simple surgery. Survival beyond 5 years at stage 2 skin cancer is excellent. Survival to or beyond 5 years at stages 3 and 4 becomes less likely. In the last 20 years, the incidence of skin cancer has increased almost tenfold.
Sunscreens do not fully prevent the possibility of skin cancer or melanoma. Sunscreens are rated according the sun protection factor (SPF) and the best sunscreens protect at a rating of 15 or higher. Sunscreens rated higher than 15 are usually less soluble and last longer. Many medical people recommend a sunscreen of SPF 30. To protect at a higher rating, proper clothing (e.g.Solumbra by Sun Precautions) must be worn since UV can still penetrate SPF 30 sunscreens. The normal cotton "tee" shirt worn in the summer protects to a SPF rating of about 10 so this is not sufficient.
To insure that a sunscreen or sunblock does indeed absorb UVB and UVA radiation, look for a circle on the bottle of sunscreen which contains both UVB and UVA or some other label indicating both. If you're uncertain that the sunscreen protects against both, the following active ingredients protect (1) against UVB (PABA derivatives such as Padimate O; cinnamates such as Parsol®MCX, Neo-Heliopan AV and Giv TanF: 2-hydroxy-4-methoxy- benzophenone; salicylates such as homosalate, Heliophan and octyl salicylate; Eusolex®8020), (2) and against UVA (dibenzoylmethanes such as avobenzone or Parsol®1789; oxybenzone). Oxybenzone gives some protection to both UVA and UVB.
The following societies have information on skin cancer:
Cancer Information Service (1-800-4-CANCER or 1-800-422-6237) American Cancer Society (1-800-227-2345) Skin Cancer Foundation (1-212-725-5176)
Dr. J. E. Spellman of Beebe Hospital also runs regular informational seminars that are advertised in the local Lewes newspapers.
On the web, check: http://www.medicinenet.com. You may want to bookmark it for future reference. You will find a menu where you can click "Diseases & Treatments". Then a disclaimer page appears which lets you know this is for information purposes only. You'll click "I Agree!" and then another page will come up listing the alphabet by letter. Click "C" for cancer. There you will find a list which has "Cancer, Melanoma" listed along with many others.
The following list is not all inclusive but indicates some of the major items to look for.
I. On a monthly basis check all moles using the ABCD approach.
B) Border - melanoma lesions often have uneven or irregular borders.
C) Color - melanoma lesions often contain many shades of brown or black; benign moles are usually a single shade of brown.
D) Diameter - melanoma lesions are often more than 6mm in diameter; benign moles are less than 6mm.
III. Who is at risk?
B) People with relatives who have had skin cancer or,
C) People who have a history of one or more bad, blistering sunburns as a child or teenager or,
D) People who have already had the disease.
Kimbrough, D.R. 1997. The photochemistry of sunscreens. J. Chem. Ed., Vol. 74, 51-53.
Spellman, J.E., D. Driscoll, A. Velez and C. Karakousis. 1994. Thick cutaneous melanoma of the trunk and extremities: an institutional review. Surgical Oncology, Vol. 3, 335-343.
Taylor, J. S. 1990. DNA, sunlight and skin cancer. J. Chem. ED., Vol. 67, 835-841.
Watters, C., A. Keeney, C. T. Wigal, C. R. Johnston and R. D. Cornelius. 1997. The spectrophotometric analysis and modeling of sunscreens, J. Chem. Ed., Vol. 74, 99-102.
"What you need to know about moles and Dysplastic Nevi", National Cancer Institute, NIH Publication No. 93-3133, revised March 1993-R.
"Understanding melanoma", Schering Corporation, Kenilworth, NJ, 1996.
"Sun Protective Clothing and Accessories", Sun Precautions, 2815 Wetmore Ave., Everett, WA 98201.
George W. Luther, III