User talk:209.172.11.17

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[edit] sunscreen cancer issue

From an Epidemiological point of view the connection between sunscreen and melanoma has been proven by Westerdahl [1]

They considered the sunbathing behavior and the skin type and yet they found in equal groups a higher risk of melanoma for those individuals that use sunscreen.

Autier found aswell that sunscreen users have more melanoma than non-users.

The amount of melanoma increased drastically in Queensland after sunscreens were introduced there!! At first this increase was not seen in neighbouring Australian regions - this proves that it is not the Ozone issue!!!!

From a mechanistic point of view: It is well known, that many sunscreen ingredients are free radical generators. Once the active ingredient (UV-filter) has penetrated into the skin these free radicals cause mutations via the indirect DNA-damage. It was never disputed, that sunscreen ingredients that get into contact with living tissue act as photosensitizers and do harm. The only thing that is disputed by those who endorse sunscreen is that sunscreen penetrates into the skin. Even those people that are in favour of sunscreen-use, do admit that 1-10% of the active ingredient is absorbed into the skin. A simple back of an envelope calculation can show that this leads to a concentration that is many times higher than the established harmful concentration of c=10 μmol/liter. The problem is, that dermatologist had not understood how harmful even small concentrations of a photoactive substance can be. The free radical generation of absorbed UV-filters dominates over the protective effect of UV-filters on the surface after 20 minutes after the application of the sunscreen. [2] Gerriet42 (talk) 08:34, 26 February 2008 (UTC)

[edit] References

  1. ^ Westerdahl J; Ingvar C; Masback A; Olsson H (2000). "Sunscreen use and malignant melanoma.". International journal of cancer. Journal international du cancer 87: 145-50. 
  2. ^ Hanson Kerry M.; Gratton Enrico; Bardeen Christopher J. (2006). "Sunscreen enhancement of UV-induced reactive oxygen species in the skin". Free Radical Biology and Medicine 41 (8): 1205-1212.