Protection Against Photoaging and Skin Cancer The importance of UVA and UVB solar radiation protection is a central issue in choosing a daily homecare routine. As we know, UV Radiation from the sun (and tanning beds) is considered the primary cause of premature aging of the skin, known as photo-damage, with loss of elasticity, wrinkles, irregular pigmentation, capillary distention, dryness and weakening of the body’s immune system. Photo-damage is caused by frequent and/or prolonged, unprotected exposure to sunlight. The damage may be either short term or chronic. Acute damage includes the familiar, painful sunburn with subsequent suntan; drug and disease induced photosensitivity; and alterations of the skin’s immune system. Chronic photo-damage promotes pre-cancer and cancer, as well as the benign, cosmetically unattractive skin changes of photoaging.
Over exposure to sunlight is also considered the main cause of skin cancer. More than 1 million Americans will be diagnosed with skin cancer this year, making it the most common cancer in the United States. Skin cancer can be deadly. The American Cancer Society expects about 7,600 deaths this year from melanoma, the most dangerous of skin cancers. Dermatologists are concerned because their skin cancer patients are younger and younger than ever before – men and women in their 20’s and 30’s!
The Sun’s Rays The level of UV light today is higher than it was 50 or 100 years ago. This is due to a reduction of ozone in the earth’s atmosphere (the Ozone Hole). Ozone serves as a filter to screen out and reduce the amount of UV light that we are exposed to. With less atmospheric ozone, a higher level of UV light reaches the earth’s surface. Sunlight contains Ultra Violet (UV) Rays. There are 3 types of UV Rays:
UVC (200-290 nm) is absorbed almost completely by the ozone layer of the earth’s stratosphere. UVC radiation is considered the most carcinogenic. UVB is approximately 10% of UV light and is the principal cause of sunburn.
UVB is a middle wavelength (290 – 320 nm) penetrating mainly in the upper layers of the skin with some into the dermal layer. UVB’s can damage the DNA at the heart of skin cells, and are one of the foremost causes of skin cancer.
UVA is approximately 90% of UV light and is considered the primary cause of premature aging of the skin and skin cancer. Unlike UVB’s which, peak in intensity from 11am to 3 pm in summer, UVA’s release energy from sun-up to sundown at the same intensity and remain pretty much the same all year round regardless of changing weather conditions. What’s more, UVA’s can pass through glass - windshields and windows don’t block them. UVA is a long wave ray (320 – 400 nm) penetrating deep into the dermal and the subcutaneous layers. These rays result in excessive oxidation of the collagen and elastin fibers, which results in a process called “cross linking.” Normally, collagen and elastin fibers are found in nice thick even rows spread parallel to the skin surface in the basal layer of the skin. With cross-linking, the fibers become entangled into many disorganized bundles which causes the skin to lose it’s elasticity and wrinkle. UVA’s can also trigger some skin allergies.
The Effects of Sun on the Skin When light first strikes the skin, it is reflected, and then it penetrates. The stratum corneum provides the greatest amount of reflection. The amount of protection depends on the condition of the stratum corneum and what the UVR comes into contact with i.e., cells, molecules, fibers or sunscreen molecules. When UVR penetrates the skin, there are many Reactive Oxygen Species (ROS) or free radicals created. These reactive particles then set off a chain reaction of damage to the cellular membrane and eventually the DNA. The first visible signs of UV damage appear with an erythema (redness) of the skin. This results from dilation of the blood vessels in the dermis as a response to the byproduct of cell damage. The severity of redness indicates the degree of damage done to the skin. The body defends itself by sending Melanocytes, which reside in the basal layer of the epidermis into action. These cells produce melanin, a skin pigment, which absorbs UV and visible light. Melanin production occurs 48 hours after exposure and peaks after two weeks.
Self-Repair Langerhans cells are the backbone of the skin’s immune system. These hardworking “sentinels” identify sun-damaged cells so that the immune system can eliminate them. But as it happens, Langerhans cells are themselves extremely sun-sensitive. UV radiation reduces the number of these essential cells and weakens the ones that remain. After UV exposure, the skin’s repair mechanism normally directs damaged cells to die. That’s why skin peels after a sunburn. All through the night, injured cells do what they can to mend themselves. But if too many cells need fixing, the repair mechanism is overwhelmed. When that happens, not every cell can be patched up. Genetic damage accumulates as normal cells die and abnormal ones survive. When it detects the presence of defective cells, the skin’s immune system springs into action. Its mission is to destroy surviving mutant cells, so that they cannot multiply and one day cause skin cancer.
Photoprotective Sunscreens There are two basic types of topical sunscreens:
• Absorbers of UV radiation – chemical sunscreen ingredients such as cinnamates, salicylates and benzophenones.
• Reflectors of UV radiation – physical sunscreen ingredients such as titanium or zinc oxide.
A third class of topical agents is the antioxidants such as vitamins E and C that do not absorb or reflect UV radiation but are believed to enhance the ability of skin cells to repair damage induced by UV radiation.
Sunscreens usually consist of several photoprotective chemicals. The degree of protection they provide is measured as a sun protective factor (SPF). The Sun Protection Factor, or SPF, stated on sunscreen products refers primarily to their capacity to block UVB radiation. The SPF number indicates how long an individual can stay out in the sun before they will burn. For example: If you normally burn within 20 minutes, an SPF of 2 would allow you to stay out 40 minutes before burning (20 minutes X SPF 2 = 40 minutes). An SPF 15 would allow you to stay out 300 minutes or 5 hours before burning (20 minutes X SPF 15 = 300 minutes). An SPF 30 would allow you to stay out 600 minutes or 10 hours before burning (20 minutes X SPF 30 = 600 minutes). However, sunscreens should be reapplied every two hours for maximum protection in the sun. An effective sunscreen should be a broad-spectrum, providing protection against both the UVA and UVB. Since most chemical ingredients of sunscreens are most effective against either UVA or UVB, many sunscreens are a mixture of UVA and UVB absorbing chemicals, or physical blocking agents such as zinc oxide. Check the label of a sunscreen product to see if it contains ingredients that provide broadspectrum UVA-UVB protection – oxybenzone, cinnamates (octylmethyl cinnamate and cinoxate), sulisobenzone, salicylates, titanium oxide, zinc oxide and avobenzone (Parsol 1789).
• Absorbers of UV radiation – chemical sunscreen ingredients such as cinnamates, salicylates and benzophenones.
• Reflectors of UV radiation – physical sunscreen ingredients such as titanium or zinc oxide.
A third class of topical agents is the antioxidants such as vitamins E and C that do not absorb or reflect UV radiation but are believed to enhance the ability of skin cells to repair damage induced by UV radiation.
Sunscreens usually consist of several photoprotective chemicals. The degree of protection they provide is measured as a sun protective factor (SPF). The Sun Protection Factor, or SPF, stated on sunscreen products refers primarily to their capacity to block UVB radiation. The SPF number indicates how long an individual can stay out in the sun before they will burn. For example: If you normally burn within 20 minutes, an SPF of 2 would allow you to stay out 40 minutes before burning (20 minutes X SPF 2 = 40 minutes). An SPF 15 would allow you to stay out 300 minutes or 5 hours before burning (20 minutes X SPF 15 = 300 minutes). An SPF 30 would allow you to stay out 600 minutes or 10 hours before burning (20 minutes X SPF 30 = 600 minutes). However, sunscreens should be reapplied every two hours for maximum protection in the sun. An effective sunscreen should be a broad-spectrum, providing protection against both the UVA and UVB. Since most chemical ingredients of sunscreens are most effective against either UVA or UVB, many sunscreens are a mixture of UVA and UVB absorbing chemicals, or physical blocking agents such as zinc oxide. Check the label of a sunscreen product to see if it contains ingredients that provide broadspectrum UVA-UVB protection – oxybenzone, cinnamates (octylmethyl cinnamate and cinoxate), sulisobenzone, salicylates, titanium oxide, zinc oxide and avobenzone (Parsol 1789).
Zinc Oxide Regardless of the knowledge that UVA rays can cause photo-aging and skin cancer, many ingredients today are lacking in effectively blocking UVA rays. Zinc Oxide blocks virtually the entire UVA and UVB spectrum. This makes Zinc Oxide the most complete block known. Zinc Oxide is a natural mineral forming a protective barrier over the skin. It is known to be stable preventing deterioration in the sun. It is the only sunscreen ingredient recognized by the FDA as a Category 1 Skin Protectant.
When Should A Sunscreen Be Applied? Sunscreens that absorb UVR need to be applied 30 minutes prior to sun exposure to give the screen time to activate. Sunscreens that reflect (Titanium Dioxide and Zinc Oxide) don’t need the extra time. However, if you have a sunscreen that is blended with both absorbers and reflectors, you must give the product the 30 minutes for the absorbers to work. On the face, sunscreens should be applied after the moisturizer (or in place of it for those clients that do not want to do the extra step). Sunscreen should be a part of everyone’s morning skin care regimen.
What Else Can I Do To Protect Myself? Sun avoidance is the best defense against premature aging of the skin and skin cancer. Wear an SPF 15 or more daily, whether you think you’ll have much exposure to the sun or not. If you love the look of a suntan, use a self-tanner. It is very important to check your skin regularly to see if you notice any changes in your skin. See your doctor if you notice any changes in moles you might have or if a sore on your skin does not heal
article source : http://onlyyourskincare.co.uk/
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