8 Shade Planning for America’s Schools Chapter 1 sun-reactive types, ranging from those with blue or green eyes and very light skin that never tans to those with very dark hair and eyes and dark skin that almost never burns. Although sunburn is not as common among blacks, compared to whites, blacks are susceptible. Approximately 15% of the African American respondents to a national health survey reported experiencing mild to severe sunburns.6 6 Hall HI, Rogers JD. Sun protection behaviors among African Americans. Ethnicity and Disease 1999;9(1):126-31. Differences also exist in the sunsensitivity of different parts of the body. The face, neck, and trunk are two to four times more sensitive than the limbs.7 7 Olson RL, Sayre RM, Everett M A. Effect of anatomic location and time on ultraviolet erythema. Arch Dermatol 1996;93(2): 211-15. Tanning Tanning, or melanin pigmentation, is a consequence of overexposure to the sun that many people find desirable. UVA exposure results in the skin’s production of more melanin, the substance responsible for skin’s pigmentation. There are two ways in which our skin can tan, by immediate tanning and by delayed tanning. Immediate tanning occurs as quickly as 5 to 10 minutes after exposure to the sun and will last as long as 2 hours. One’s ability to exhibit immediate tanning is directly related to the genetically determined pigmentation of the skin. Delayed tanning, which is the more familiar form of tanning, is noticeable 1 to 2 days after exposure, increases for several days, and lasts for weeks or months. Although having a tan provides some degree of protection from UVB, melanin is not an effective sunscreen for Caucasian skin.8 8 Diffey BL. Ultraviolet radiation and human health. Clinics in Dermatology 1998;16:83-9. Photosynthesis of Vitamin D 3 The only positive health effect associated with exposure to solar UV radiation is the synthesis of vitamin D3 . Without UVB, the body cannot synthesize vitamin D3 , which is essential for regulating calcium metabolism. Few studies have examined the effect of sun avoidance or the use of sunscreen on the production of vitamin D3 in children or adults. Therefore, the American Academy of Pediatrics has recommended that infants, children, and adolescents who do not consume at least 500 mL (16.9 oz) of vitamin D-fortified milk or formula daily should take one of the many available daily multivitamin supplements that contain 400 IU of vitamin D3 . 9 9 Gartner LM, Greer FR. Prevention of rickets and vitamin D deficiency: new guidelines for vitamin D intake. Pediatrics 2003;111(4 Pt 1): 908-10. Photoaging of the Skin Exposure to UVA and UVB radiation, and perhaps to radiation in the infrared range as well,8 causes photoaging, a process in which the skin’s elastic fibers break down leading to wrinkled and leathery-looking skin. Dryness, deep wrinkles, sagging, loss of elasticity, and mottled pigmentation are all photoaging symptoms . Eye Damage Eye damage from solar radiation is a risk factor for developing a number of eye disorders including cataracts, skin cancer around the eyes and degeneration of the macula. Although the evidence is not conclusive, such damage appears to have a dose-response relationship and to be cumulative; that is, the more unprotected solar radiation exposure to the eyes over an entire lifetime, the greater one’s risk for developing cataracts.8, 10, 11 10 West SK, Duncan DD, Munoz B, Rubin GS, Fried LP, Bandeen-Roche K, et al. Sunlight exposure and risk of lens opacities in a population-based study: the Salisbury Eye Evaluation project. JAMA1998;280:714-8. 11 Rosmini F, Stazi MA, Milton RC, Sperduto RD. Pasquini P, Maraini G. A dose-response effect between a sunlight index and age-related cataracts. Italian-American Cataract Study Group.[comment]. Annals of Epidemiology. 4(4):266-70.
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