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EXPOSURE TO ULTRAVIOLET (UV) LIGHT

EXPOSURE TO ULTRAVIOLET (UV) LIGHT. Sophie J. Balk, M.D. Professor of Clinical Pediatrics Albert Einstein College of Medicine NEETF Children’s Environmental Health Faculty Champions Initiative. www.charlie.org. GOALS: TO DISCUSS. Background on UV radiation (UVR) Health effects

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EXPOSURE TO ULTRAVIOLET (UV) LIGHT

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  1. EXPOSURE TO ULTRAVIOLET (UV) LIGHT Sophie J. Balk, M.D. Professor of Clinical Pediatrics Albert Einstein College of Medicine NEETF Children’s Environmental HealthFaculty Champions Initiative

  2. www.charlie.org

  3. GOALS: TO DISCUSS.. • Background on UV radiation (UVR) • Health effects • Focus on skin cancer • Prevention messages • What to ask in the history • Resources

  4. SUNLIGHT

  5. UVR MODIFIED BY PASSAGE THROUGH ATMOSPHERE…. • Stratosphere (10 - 50 Km above sea level) • Absorption by ozone • Scattering by molecules • Troposphere (0 -10 Km above sea level) • Absorption by pollutants • Scattering by particulates • Clouds

  6. INCREASED UV INTENSITY... • At midday • In summer • Closer to the equator • At higher altitudes • Reflected from ground surfaces, sand, snow, water

  7. HEALTH EFFECTS OF UVR • Skin • Eyes • Immune system AAP Pediatric Environmental Health, November 2003.

  8. EFFECTS ON THE SKIN • Vitamin D Production • Erythema and sunburn • Tanning • Skin aging • Photosensitivity • Non-melanoma skin cancer • Basal cell carcinoma • Squamous cell carcinoma • Melanoma AAP Pediatric Environmental Health, November 2003.

  9. American Cancer Society 2006 ( www.cancer.org)

  10. Gilchrest et al. NEJM April 1999.

  11. ERYTHEMA & SUNBURN • Minimal erythemal dose (MED) depends on • Skin type and thickness • Amount of melanin and ability to produce melanin after exposure • Intensity of the radiation • Six sun-reactive skin types

  12. SKIN TYPES

  13. TANNING • Protective response to sun exposure • Immediate tanning: Induced by UV-A, no new melanin • Delayed tanning: Induced by UV-B, begins at 2-3 days, peaks at 7-10 days, new melanin formed

  14. NON-MELANOMA SKIN CANCER (NMSC) • Basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) • Most common malignancies in adults: > 1,000,000/year • Found on maximally-exposed areas • Usually not fatal unless untreated • Related to cumulative sun exposure American Cancer Society 2006 ( www.cancer.org). Accessed 6-28-06.

  15. MELANOMA • Most common fatal skin cancer • 2006: 62,190 new cases with 7,910 deaths1 • Occurs in teens, young adults • Metastatic melanoma has a grave prognosis • Prevention, early detection are key 1 – American Cancer Society 2006 (www.cancer.org). Accessed 6-28-06.

  16. MELANOMA IN YOUNG ADULTS AND CHILDREN • A common malignancy in whites1 • 2nd most common, women 20 – 29 • 3rd most common, men 20 - 29 • Melanoma in children2 • Incidence rising • 33 patients < 14; 25 yr experience • Presentation often atypical: most lesions raised, well-defined borders • Lesions unlike any other on child 1 - Wu et al. Cancer Causes and Control 2005; 2 - Ferrari et al, Pediatrics 2005

  17. MELANOMA A - Asymmetry B - Border C - Color D - Diameter E - Evolving

  18. MELANOMA • Lifetime risk • 1930: 1 in 1500 • 1987: 1 in 120 • 2002: 1 in 681 • 2010: 1 in 501 1- Rigel DS. Dermatol Clin 2002; 20

  19. WHY IS THE INCIDENCE OF MELANOMA RISING? • Thought to be related to sun exposure • Depletion of the ozone layer • Changing patterns of dress • More leisure time • “Sun culture” Pediatric Environmental Health. AAP 2003

  20. SUNLIGHT AND MELANOMA • Epidemiologic and biological evidence implicate sunlight in the pathogenesis of melanoma Pediatric Environmental Health. AAP 2003

  21. SUNLIGHT AND MELANOMA • Latitude • Race and pigmentation • Childhood exposure • Nevi Pediatric Environmental Health. AAP 2003

  22. CHILDHOOD EXPOSURE • ~25% of lifetime sun exposure occurs during childhood and adolescence1 • Episodic high exposures sufficient to cause sunburn, particularly in childhood and adolescence, increase the risk of melanoma2 1- Godar et al. Photochem Photobiol 2003 2 -Elwood, Jopson. Int J Cancer 1997;73

  23. CHILDHOOD EXPOSURE • Migration studies: High sun exposure during childhood is important in the pathogenesis of melanoma1 1 - Khlat et al. Am J Epidemiol. 1992;135

  24. NEVI • Acute sun exposure is implicated in the development of nevi in children1 • There is a relationship between the number and type of nevi and the development of melanoma1 • Dysplastic nevi: precursor lesions that increase risk2 1 – Gallagher et al. Arch Dermatol. 1990; 126 2 - Clark. Arch Dermatol. 1988;124

  25. BIOLOGIC EVIDENCE • UVB exposure  DNA lesions (pyrimidine dimers) whose incomplete repair leads to mutations1 • UVA causes oxidative damage to DNA  mutations1 • UVR contributes to immune suppression2 1 - Gilchrest et al. N Engl J Med. 1999;340 2 – Strickland, Kripke. Clin Plast Surg. 1997;24

  26. BIOLOGIC EVIDENCE: XP • Xeroderma pigmentosum (XP): Grossly deficient repair of DNA damaged by UVR1 • SCC, BCC and melanoma seen beginning at young ages1 1 - Photosensitivity. In Behrman, Kliegman, Jenson, eds. Nelson Textbook of Pediatrics. 16th ed. Philadelphia, PA: WB Saunders Co; 2000:1998-2001

  27. SUN PROTECTION • Sun protection is recommended to prevent skin cancer, including melanoma • Sun protection is recommended beginning early in life • Pediatric clinicians may play an important role in delivering messages Pediatric Environmental Health. AAP 2003

  28. PREVENTION AT ALL DEVELOPMENTAL STAGES • Infants • Lack mobility • Skin has less melanin than at any other time • Children • New patterns of exposure • Adolescents • Susceptible to society’s ideas about beauty and health

  29. UV LIGHT – PREVENTION MESSAGES • Do not burn; avoid sun tanning and tanning beds • Generously apply sunscreen • Wear protective clothing • Seek shade • Use extra caution near water, snow and sand • www.skincancerprevention.org/Tips/tabid/54/ Default.aspx

  30. DO NOT BURN; AVOID SUN TANNING AND TANNING BEDS • Burning raises melanoma risk • Avoid/limit exposure during peak hours (10AM – 4PM) • Avoid intentional tanning

  31. GENEROUSLY APPLY SUNSCREEN • Sunscreen is the sun protection method most commonly used1 • Apply to all exposed skin using SPF > 15 • Broad protection (UVA & UVB) • Reapply often 1 - Olson et al. Pediatrics 1997;99

  32. WEAR PROTECTIVE CLOTHING • Simple, practical protection • The structure (weave) of the fabric is most important • Light-weight long pants and sleeves suggested • Hats with a bill or brim • Sunglasses

  33. SEEK SHADE • Shade is useful but… • Shade offers insufficient protection because UV light is scattered and reflected • A fair-skinned person sitting under a tree can burn in an hour

  34. SUNSCREENS • Came into use in 1950’s • Promoted tanning without burning • First true sunscreen (PABA) became available in 1970’s • High-intensity sunscreens within last 15 years Rigel DS. Dermatol Clin 2002; 20.

  35. OPAQUE SUNSCREENS • Scatter, reflect, block UV light • Zinc oxide, titanium dioxide, red vetenary petrolatum, talc • Effective for diseases related to light exposure (SLE, XP, solar urticaria) • Useful for those spending extensive periods outside Rigel DS. Dermatol Clin 2002; 20.

  36. CHEMICAL SUNSCREENS UVB: 290 – 320 nm UVA: 320 – 400 nm Rigel DS. Dermatol Clin 2002; 20.

  37. SUN PROTECTION FACTOR - SPF • Ratio of amount of time to sunburn with sunscreen compared to time to sunburn without sunscreen • 1970’s: SPF’s 2 – 4: 50 – 75% protection • High-potency sunscreens: SPF’s 15 – 50, 93 – 98% protection Rigel DS. Dermatol Clin 2002; 20.

  38. LIMITATIONS OF SPF SYSTEM • Applies to UVB protection only • Measured under ideal conditions • Concerns about: • Using adequate amounts • Applying before needed • Need for frequent reapplication

  39. SUNSCREEN AND MELANOMA • Sunscreen • Reduces sunburn • Can prevent actinic keratoses1 • Can prevent SCC2 • No conclusive data in humans to demonstrate that sunscreen prevents melanoma or BCC 1 - Thompson, Jolley, Marks. NEJM 1993; 329 2 – Green et al. Lancet 1999; 354

  40. IS SUNSCREEN USE A RISK FACTOR FOR MELANOMA? • Swedish case-control study found increased risk1 • Several studies found increased risk with sunscreen use; some studies found decreased risk; others found no change2 1 – Westerdal et al. Melanoma Res 1995; 5:59-65. 2 - Cooper, Lim. J Amer Acad Dermatol 1999; 40.

  41. IS SUNSCREEN USE A RISK FACTOR FOR MELANOMA? • No studies demonstrate that sunscreens are carcinogenic1 • Sunscreen users may extend their time out in the sun2 • There may be greater exposure to UVA1 1-Cooper, Lim. J Amer Acad Dermatol 1999; 40 2-Autier et al. J Natl Cancer Inst. 1999;91:1304-1309

  42. SUNSCREEN MAKERS SUED FOR MISLEADING CLAIMS • April 2006: 9 suits involving popular brands charged that manufacturers inflated claims about sunscreens’ protection • Sunscreen called the “snake oil of the 21st century“ • Focus on labels claiming equal UVA/UVB protection; “all day”; “waterproof”; www.consumeraffairs.com/news04/2006/03/sunscreen.html. Accessed 7-29-06

  43. RECOMMENDATIONS • AAP, ACS, AAD, EPA, CDC, others recommend multi-component message • Sunscreen is one part of a sun protection program • Sunscreen should not be used to extend time spent in the sun

  44. SUNSCREEN AND VITAMIN D METABOLISM • Vitamin D produced in the skin by action of UVB • Inadequate sunlight is an important risk factor for rickets • Concerns that sunscreen use may affect levels of Vitamin D

  45. SUNSCREEN AND VITAMIN D METABOLISM • AAP policy - April 2003 • Infants need 200 IU Vit D/day • Human milk: < 25 IU/L Vit D • Infant formula: 400 IU/L Vit D • Supplementation: all breast-fed infants, formula-fed infants taking <500 ml/day, children with inadequate intake/sun AAP Section on Breastfeeding and Committee on Nutrition. Pediatrics 2003; 111.

  46. VITAMIN D AND CANCER PREVENTION • Recent studies suggest a role for vitamin D in cancer prevention • Colon, breast, prostate, lung • High prevalence of vitamin D deficiency/insufficiency • Insufficient evidence to make recommendations about sun exposure http://msnbc.msn.com/id/7875140/print/1/displaymode/1098. Accessed 7-04-06

  47. People Magazine May 05

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