Saturday, January 3, 2009

Sarah Palin, vitamin D and tanning beds, part 2.

To determine whether Sarah Palin was justified in installing a tanning bed in the Alaska Governor’s mansion, we need to decide whether or not the fear regarding sunlight as a cause of melanoma is justified. Tanning beds, you see, emit the same type of ultraviolet light (UV) as summer sun. First of all, let’s take a look at the history of UV exposure since 1900. That year, approximately 75% of the population of the US worked outdoors; today, only 10% work outdoors.[1] Yet, with this profoundly decreased exposure to sunlight, melanoma has increased dramatically in every age group since that time; for example, the lifetime risk of melanoma in 1930 was one in 1,500, whereas the risk today is one in 60. Is there something wrong with this scenario? If sunlight exposure causes melanoma, shouldn't melanoma incidence decrease with decreasing sunlight exposure?

Other troubling facts for the dermatologists who march in lock-step with official policy: seventy-eight percent of all melanomas occur on areas of the body that are seldom exposed to sunlight,[2] and people who work indoors develop 50% more melanomas than those who work outdoors.[3] Furthermore, among black people, nearly all melanomas occur on the soles of the feet and on the lower legs.[4] Melanomas in women occur primarily on the upper leg and in men occur primarily on the back.[5] These cancers also occur inside the mouth,[6] on sex organs[7] and in the armpits[8]—all areas of little or no sunlight exposure.

So here is my question for you to consider: Do you believe that sunlight causes melanoma? In other words, is the “sunlight creates melanoma” theory reasonable? Stay tuned for part three.

[1] Genuis, S. Keeping your sunny side up: How sunlight affects health and well-being. Can Fam Physician. 2006 April 10; 52(4): 422–423
[2] Christophers, A. Melanoma is not caused by sunlight. Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 1998;422:113-17.
[3] Garland F. et al. Occupational sunlight exposure and melanoma in the USA Navy. Arch Environ Health 1990; 45:261-67.
[4] Crombie, I. et al. Racial differences in melanoma incidence. Br J Cancer 1979;40:185-93.
[5] Hakansson, N. et al. Occupational sunlight exposure and cancer incidence among Swedish construction workers. Epidemiology 2001;12:552-57.
[6] Burgess, A. et al. Parotidectomy: preoperative investigations and outcomes in a single surgeon practice. ANZ J Surg. 2008 Sep;78(9):791-3.
[7] Ribé, A Melanocytic lesions of the genital area with attention given to atypical genital nevi J Cutan Pathol. 2008 Nov;35 Suppl 2:24-7.
[8] Rhodes, A. Melanoma’s Public Message. Guest editorial, Skin and Allergy News 2003;34

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megha said...
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