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Sure, but higher melanin (ie, darker skin pigmentation) is correlated with lower cancer rates [1][2]. So the point is that cultural changes are causing people w

Sure, but higher melanin (ie, darker skin pigmentation) is correlated with lower cancer rates [1][2]. So the point is that cultural changes are causing people who were previously were at lower risk of cancer due to their skin pigmentation/higher melanin, to now have reducing melanin/pigmentation, therefore increasing rates of skin cancer. [1] https://www.cancer.org/cancer/skin-cancer/prevention-and-early-detection/sun-damage.html https://www.cancer.org/cancer/skin-cancer/prevention-and-ear... [2] https://www.cdc.gov/cancer/skin/statistics/race.htm https://www.cdc.gov/cancer/skin/statistics/race.htm

kgwgk 9y ago
Aren't those links about "people with naturally darker skin"? I'm not sure how cultural changes can affect that. Rich people may eat caviar, but eating caviar won't make you rich...
- Sean1708 9y ago
  > The tan is caused by an increase in the activity and number of melanocytes, the cells that make the pigment melanin. Melanin helps block out damaging UV rays up to a point, It's not particularly clearly worded but to me that seems to suggest that tanning increases melanin and that melanin helps prevent cancer regardless of whether your dark skin is natural or tanned.
  - kgwgk 9y ago
    But if tanning also produces cancer it remains to be determined which effect dominates (unlike for people with naturally dark skin, where the effect can only go in the beneficial sense).
    - scott_s 9y ago
      Indoor tanning is associated with higher rates of skin cancer: https://www.cdc.gov/cancer/skin/basic_info/indoor_tanning.htm https://www.cdc.gov/cancer/skin/basic_info/indoor_tanning.ht... I suspect outdoor tanning is as well.
    - Bartweiss 9y ago
      Broadly, my understanding is that a major change in skin tone is 'worth' about 15 SPF, so tanning would fall somewhere below that. For a fixed amount of sun exposure, spreading out the duration is better both to establish a tan and to allow more time for skin recovery. But there isn't really a case where tanning increases safety, because you get the tan via exposure. It's like saying pilots who practice a lot are safer; for any given flight it might be true, but cumulative risk can only rise.
    - Sean1708 9y ago
      I thought it was burning that was associated with an increased cancer risk, not just tanning in general?
    - Fishkins 9y ago
      Every source I've seen clearly states tanning always increases your chance of skin cancer. Tanning does provide a small amount of protection against burning (around 3 SPF worth), but no protection against cancer. https://www.scientificamerican.com/article/fact-or-fiction-a-base-tan-can-protect-against-sunburn/ https://www.scientificamerican.com/article/fact-or-fiction-a...
      - Retric 9y ago
        They studied based on 2 weeks of tanning which is very minimal. You clearly get more than SPF 3 with a deep tan as you can spend 8 hours in direct sun without obvious problems. Without any tan you get a burn in under an hour suggesting ~SPF 10+.
- spraak 9y ago
  That's what the above poster already said. > people who were previously were at lower risk of cancer due to their skin pigmentation/higher melanin
  - kgwgk 9y ago
    Unless the above poster means “due to their [acquired] skin pigmentation” I don’t see how the comment can make any sense. Why would their rates of skin cancer be higher now?
    - loeg 9y ago
      Maybe OP is referring to spray tans? That's my best guess.
- tomhoward 9y ago
  We know that genetics and environment both play a significant role. So think about it this way: If you're genetically predisposed to having very dark skin, you will be able to tolerate more UV exposure without significantly increasing your risk of cancer. And by continuing to be exposed to high UV levels, your body will continue to produce melanin to keep you protected. It's a feedback loop. If you're genetically predisposed to having pale skin, but then expose your skin to higher levels of UV than your low melanin levels can guard against, you will sustain significant sunburn, and if you do this repeatedly you'll significantly increase your risk of skin cancer. But if you gradually expose yourself to moderate levels of UV you can gradually increase your melanin levels more safely, but only as far as your genetics allow. (This is theoretical of course; we know very well that it's very hard for fair-skinned people to expose themselves to UV light from the sun or tanning beds without overdoing it, hence the widespread occurance of skin cancer.) My educated guess about the notion that dark skinned people are experiencing higher levels of cancer would be that if a dark-skinned person keeps avoiding UV for long enough, their melanin levels start to decline (due to it not being an optimal use of resources), but then if/when sun exposure happens, the protection isn't as strong and the risk of cancer is higher.
  - angry_octet 9y ago
    The notion of 'building up a tan' is dangerously wrong advice. Even for people with darker skin it is unwise to have significant bursts of UV exposure. I'm curious as to whether your educated guess derives from a clinical background, or reddit? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671032/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671032/ http://www.skincancer.org/prevention/skin-cancer-and-skin-of-color http://www.skincancer.org/prevention/skin-cancer-and-skin-of... https://theconversation.com/amp/sun-damage-and-cancer-how-uv-radiation-affects-our-skin-34538 https://theconversation.com/amp/sun-damage-and-cancer-how-uv... http://enhs.umn.edu/current/5103/uv/molelcularmech.html http://enhs.umn.edu/current/5103/uv/molelcularmech.html
    - tomhoward 9y ago
      The notion of 'building up a tan' is dangerously wrong advice. I know, I acknowledged that in my comment. My main point was only about the extent to which people with genetically high melanin levels are at much lower risk of cancer (which your first link confirms), but how their risk might increase if their melanin levels drop. I don't dispute that it's a complex and dangerous topic. And as someone with genetically very pale skin, I most certainly steer well clear of direct sunlight and make no efforts to develop a tan. I'm curious as to whether your educated guess derives from a clinical background, or reddit? That's a low blow :) I rarely go anywhere near Reddit, certainly not for anything to do with health. I have spent 10+ years researching health topics for reasons to with serious, chronic, illnesses I've endured, and have now largely overcome thanks to what I've learned.

kgwgk 9y ago

Aren't those links about "people with naturally darker skin"? I'm not sure how cultural changes can affect that. Rich people may eat caviar, but eating caviar won't make you rich...

Sean1708 9y ago
> The tan is caused by an increase in the activity and number of melanocytes, the cells that make the pigment melanin. Melanin helps block out damaging UV rays up to a point, It's not particularly clearly worded but to me that seems to suggest that tanning increases melanin and that melanin helps prevent cancer regardless of whether your dark skin is natural or tanned.
- kgwgk 9y ago
  But if tanning also produces cancer it remains to be determined which effect dominates (unlike for people with naturally dark skin, where the effect can only go in the beneficial sense).
  - scott_s 9y ago
    Indoor tanning is associated with higher rates of skin cancer: https://www.cdc.gov/cancer/skin/basic_info/indoor_tanning.htm https://www.cdc.gov/cancer/skin/basic_info/indoor_tanning.ht... I suspect outdoor tanning is as well.
  - Bartweiss 9y ago
    Broadly, my understanding is that a major change in skin tone is 'worth' about 15 SPF, so tanning would fall somewhere below that. For a fixed amount of sun exposure, spreading out the duration is better both to establish a tan and to allow more time for skin recovery. But there isn't really a case where tanning increases safety, because you get the tan via exposure. It's like saying pilots who practice a lot are safer; for any given flight it might be true, but cumulative risk can only rise.
  - Sean1708 9y ago
    I thought it was burning that was associated with an increased cancer risk, not just tanning in general?
  - Fishkins 9y ago
    Every source I've seen clearly states tanning always increases your chance of skin cancer. Tanning does provide a small amount of protection against burning (around 3 SPF worth), but no protection against cancer. https://www.scientificamerican.com/article/fact-or-fiction-a-base-tan-can-protect-against-sunburn/ https://www.scientificamerican.com/article/fact-or-fiction-a...
    - Retric 9y ago
      They studied based on 2 weeks of tanning which is very minimal. You clearly get more than SPF 3 with a deep tan as you can spend 8 hours in direct sun without obvious problems. Without any tan you get a burn in under an hour suggesting ~SPF 10+.
spraak 9y ago
That's what the above poster already said. > people who were previously were at lower risk of cancer due to their skin pigmentation/higher melanin
- kgwgk 9y ago
  Unless the above poster means “due to their [acquired] skin pigmentation” I don’t see how the comment can make any sense. Why would their rates of skin cancer be higher now?
  - loeg 9y ago
    Maybe OP is referring to spray tans? That's my best guess.
tomhoward 9y ago
We know that genetics and environment both play a significant role. So think about it this way: If you're genetically predisposed to having very dark skin, you will be able to tolerate more UV exposure without significantly increasing your risk of cancer. And by continuing to be exposed to high UV levels, your body will continue to produce melanin to keep you protected. It's a feedback loop. If you're genetically predisposed to having pale skin, but then expose your skin to higher levels of UV than your low melanin levels can guard against, you will sustain significant sunburn, and if you do this repeatedly you'll significantly increase your risk of skin cancer. But if you gradually expose yourself to moderate levels of UV you can gradually increase your melanin levels more safely, but only as far as your genetics allow. (This is theoretical of course; we know very well that it's very hard for fair-skinned people to expose themselves to UV light from the sun or tanning beds without overdoing it, hence the widespread occurance of skin cancer.) My educated guess about the notion that dark skinned people are experiencing higher levels of cancer would be that if a dark-skinned person keeps avoiding UV for long enough, their melanin levels start to decline (due to it not being an optimal use of resources), but then if/when sun exposure happens, the protection isn't as strong and the risk of cancer is higher.
- angry_octet 9y ago
  The notion of 'building up a tan' is dangerously wrong advice. Even for people with darker skin it is unwise to have significant bursts of UV exposure. I'm curious as to whether your educated guess derives from a clinical background, or reddit? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671032/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2671032/ http://www.skincancer.org/prevention/skin-cancer-and-skin-of-color http://www.skincancer.org/prevention/skin-cancer-and-skin-of... https://theconversation.com/amp/sun-damage-and-cancer-how-uv-radiation-affects-our-skin-34538 https://theconversation.com/amp/sun-damage-and-cancer-how-uv... http://enhs.umn.edu/current/5103/uv/molelcularmech.html http://enhs.umn.edu/current/5103/uv/molelcularmech.html
  - tomhoward 9y ago
    The notion of 'building up a tan' is dangerously wrong advice. I know, I acknowledged that in my comment. My main point was only about the extent to which people with genetically high melanin levels are at much lower risk of cancer (which your first link confirms), but how their risk might increase if their melanin levels drop. I don't dispute that it's a complex and dangerous topic. And as someone with genetically very pale skin, I most certainly steer well clear of direct sunlight and make no efforts to develop a tan. I'm curious as to whether your educated guess derives from a clinical background, or reddit? That's a low blow :) I rarely go anywhere near Reddit, certainly not for anything to do with health. I have spent 10+ years researching health topics for reasons to with serious, chronic, illnesses I've endured, and have now largely overcome thanks to what I've learned.