![]() ![]() Vitamin D and bones Vitamin D and other disorders Public health messageġ1 Definitions 7-dehydrocholesterol: provitamin D3 Shade Clothing Education Public policy Sunscreen useġ0 Vitamin D Definitions Vitamin D: UVB induced production in the skin Skin cancer risk is higher in susceptible populations living closer to the equator The higher the total lifetime amount of UV exposure, the greater the risk of skin cancer An intermittent pattern of intense exposure appears to increase the risk of melanoma People with sun-sensitive skin (i.e., burn easily, tan poorly), blue eyes, many nevi are at greater risk of developing skin cancerĦ UV: DNA damage Cyclobutane pyrimidine dimers : signature mutationĦ-4 pyrimidine pyrimidone photoproducts Single strand breaks DNA protein crosslinksĪctivation of surface receptors with induction of multiple signal transduction pathways: alteration in activation of many cellular proteins……alteration in gene expression and cellular functionĨ UV induces an alteration in immune surveillanceĭecreased ability to eliminate cancerous growths Interference with development of contact hypersensitivityĩ Public health message: sun protection/skin cancer prevention 3-year moving averages standardized to the Canadian 1991 population.ĥ Ambient UV, type and amount of exposure and susceptibility determine risk Melanoma incidence and mortality rates have risen 2-3 fold in 30 years Melanoma incidence and mortality, Ontario, Source: Cancer Care Ontario (Ontario Cancer Registry, 2004). ![]() Skin cancer in /3 of new cancers Source: Canadian Cancer Statistics 2005 Sun exposure is the major environmental cause of skin cancer BCC, SCC Melanoma International Agency for Research on Cancer, 1992 National Toxicology Program, Report on Carcinogens, 2000, 2002ģ Skin cancer is common > 80,000 Canadians were diagnosed with ![]() What’s the right balance for sun exposure? 1 Vitamin D synthesis and photocarcinogenesis ![]()
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