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Image result for Acne We know from A Solution To Your Dark Spot post that longterm exposure to the sun can cause skin hyperpigmentation and make your dark spots worse. It is imperative that you choose the best sunscreens for your skin, you do not get deceived by marketing claims and tricks. The UV spectrum is broken into three major bands: ultraviolet C (UVC), ultraviolet B (UVB), and ultraviolet A (UVA) and they all can induce or worsen sun-induced skin disorders. UVA radiation (wavelength between 320 and 400 nm) is involved in suppressing the immune system and damaging DNA, which result in premature photoaging and skin cancers. UVB (wavelength between 290 and 320 nm) is noted for causing sunburn or reddening of the skin ( erythema). The intensity of UVB radiation striking the Earth is the greatest from 10:00 AM to 4:00 PM. As a result, UVB is considered the primary inducer of skin cancer. However, its ability to cause cancer (carcinogenic effect) is increased by UVA. The only thing that can cure UVB exposure in the skin is the synthesis of vitamin D3 in our skin. We can get this from vitamin D–rich foods and vitamin D supplements. Most UVC radiation (wavelength between 200 and 290 nm) is screened out by the ozone layer of the upper atmosphere, and only a limited amount of it reaches Earth. Most of the UVC that strikes the skin is absorbed by the dead cell layer of the stratum corneum Although UVB does not infiltrate window glass, UVA does. Most automobile windshields are made from laminated glass that filters most of the UVA. However, side windows are not constructed from a laminated glass; therefore, a notable amount of UVA may pass through to passengers in the vehicle. UVR-induced skin disorders can be prevented by minimizing exposure to UVR and by using sunscreen agents. Let’s discuss SPF and how not to get fooled when buying sunscreen…. Image result for physical sunscreen SSPF (sun protection factor) is a relative measure of how long a sunscreen will offer you from both UVA and UVB radiation protection. Only broad-spectrum sunscreens with an SPF value of 15 or higher will be able to claim to decrease the risk of skin cancer and early skin aging if they are used as directed along with other skin protection devices. Broad-spectrum sunscreens with an SPF value between 2 and 14 and products that protect against only UVB (not broad spectrum) can claim only to help prevent sunburn. Products that are not broad spectrum must carry a label warning: “Skin Cancer/Skin Aging Alert: Spending time in the sun increases your risk of skin cancer and early skin aging. This product has been shown only to help prevent sunburn, not skin cancer or early skin aging.” The maximum SPF value on sunscreen levels is limited to “50+.” because there is a lack of sufficient evidence that products with SPF values higher than 50 provide more protection than products with SPF values of 50. Types of Sunscreen and how to choose the right kind for you  Chemical Sunscreen Image result for chemical sunscreen Aminobenzoic Acid and Derivatives Aminobenzoic Acid use to be the most widely used sunscreen agent; however, it has been replaced by other agents because it is a significant sensitizer meaning it cause many people to develop an allergic reaction. Aminobenzoic acid is an effective UVB sunscreen, particularly when formulated in a hydroalcoholic base (maximum of 50%–60% alcohol). This causes it to penetrate into the layer of the skin and provide lasting protection, but there are side effects such as contact dermatitis, photosensitivity, stinging and drying of the skin, and yellow staining of clothes on exposure to the sun. Anthranilates The anthranilates are ortho-aminobenzoic acid derivatives. Meradimate, the menthyl ester of anthranilic acid, is a weak UV sunscreen with maximal absorbance in the UVA range. It is usually found in combination with other sunscreen agents to provide broader UV coverage. Benzophenones The benzophenone group has dioxybenzone, oxybenzone (benzophenone-3), and sulisobenzone (benzophenone-4). Many sunscreen formulations now contain benzophenones, because these agents have a broad spectrum of action and are less likely to cause allergic reactions than some of the other sunscreen classes. Oxybenzone, also found in some cosmetic formulations, is a significant sensitizing agent among sunscreens. Cinnamates Cinnamates include cinoxate, octinoxate, and octocrylene. Cinoxate and octinoxate have similar absorbance ranges and maximum absorbances. Octocrylene can decrease the rate at which other sunscreens degrade upon sun exposure. It often is combined with other sunscreens to improve their stability. Unfortunately, cinnamates do not adhere well to the skin and must rely on the vehicle in a given formulation for their efficacy. Avobenzone Avobenzone (butyl methoxydibenzoylmethane, known initially as Parsol 1789) is the first of a new class of sunscreen agents effective throughout the entire UVA range (320–400 nm; full spectrum). It has a maximum absorbance at approximately 360 nm. Salicylates Salicylic acid derivatives are weak sunscreens and must be used in high concentrations. They do not adhere well to the skin and are easily removed by perspiration or swimming. Other Chemical Sunscreens Ensulizole is a pure UVB sunscreen with an absorbance range of 290–320 nm. Ecamsule (terephthalylidene dicamphor sulfonic acid) is a new molecule that FDA approved in 2006. It is a water-resistant, broad-spectrum sunscreen. Ecamsule is often combined with octocrylene to enhance its stability to light. Physical Sunscreen Image result for physical sunscreen Physical sunscreens such as zinc oxide and titanium dioxide are broad-spectrum UV protectants. Because titanium dioxide increases the effective SPF of a product and extends the spectrum of protection well into the UVA range, the number of commercial products containing this agent has increased. References


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