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UVA & UVB Damage
Both of these forms of radiation have been strongly linked to skin cancer and a weakening of the immune system. Together, they cause premature ageing, increased chance of skin cancer, cataracts, and skin pigmentation irregularities. UVB rays cause a visible burn turning the skin red almost as soon as the burn has happened. This painful condition is often enough to drive some out of the sun, but many people choose to remain. Excessive burning and tanning leads to toughening of the skin, deep wrinkle formation, and dark spots in all ages of sun bathers. UVA is more difficult to detect and it appears to do less damage in the short term, but this is deceptive. UVA penetrates 30% deeper than UVB reaching down under the skin to damage the tissues below. Instead of being visible in just a few hours, this damage takes years to become visible but when it does, it is extreme. Because this form of radiation penetrates under the skin, the skin cancer that forms is often not visible for weeks or months after it has formed. This makes UVA one of the most lethal forms of radiation we experience today.1
1 Armstrong, B.K., and A. Kricker, How much melanoma is caused by sun exposure?, Melanoma Research, 1993: 3:395-401.
UV’s Effects On Skin
You may already know that UV radiation damages the skin and it is obvious that lighter skin and freckles mean greater risk, but do you know exactly how UV causes cancer? Many researchers agree that because DNA absorbs UVA and UVB very efficiently, the amount of energy delivered into the DNA during a typical burn is so great that the DNA can’t handle the extra energy and it blows apart. Cells have a self-repair mechanism that can “stitch” the DNA back together. This happens every day in every one of your cells, but if the damage is too great to repair, the cell dies. This is where that peeling “lizard skin” comes from when you get a UV radiation burn. But what about the cells that don’t die? Each cell that survives must repair its own DNA and with each repair there is a chance for a mistake leading to mutation. Of the trillions of repairs that happen in your lifetime, only a few might lead to bad DNA mistakes and cancer, but when you get a UV burn, you might have hundreds of thousands of these repairs happen within the next two week healing period. Burn just a few times in your life and you have more than doubled your chance of skin cancer, and not when you are old. Up to 90% of the visible skin changes commonly attributed to aging are caused by sun exposure.2 It can happen at any time after the burn, even in children. Blistering sunburns during childhood significantly increase the risk of developing skin cancer later in life.3 Between 1973 and 2003, cutaneous melanoma (Skin Cancer) increased by 81 percent.4
2 Taylor, C.R. et al, Photoaging/Photodamage and Photoprotection, J Am Acad Dermatol, 1990: 22: 1-15.
3 American Academy of Pediatrics, Ultraviolet Light: A Hazard to Children, Pediatrics, 1999:104: 328-333.
4 Ries, L.A.G, D. Harkins, M. Krapcho, A. Mariotto, B.A. Miller, N. Howlander, M. Hayat, B.F. Hankey, B.K. Edwards (eds), SEER Cancer Statistics Review, 1975-2003, National Cancer Institute. Bethesda, MD, http://seer.cancer.gov/csr/1975_2003/, based on November 2005 SEER data submission, posted to the SEER Web site, 2006.