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Blue light is not ionizing radiation. In fact, not even UV-C is ionizing. You have to get shorter-wavelength than UV to ionize. UV is harmful because it has eno

Blue light is not ionizing radiation. In fact, not even UV-C is ionizing. You have to get shorter-wavelength than UV to ionize. UV is harmful because it has enough energy to at least excite electrons to higher energy levels which can lead to, I think, changes in bond rotations, but not outright ionization. UV is clearly dangerous, but not because it ionizes. I'm not sure how the transparency argument is relative. You seem to be confusing energy, which depends on the frequency of individual photons with intensity, which is the number of photons. Shine all the low-energy photons you want, and you're just going to add heat, not create photo-products or ionize.

kortex 7y ago
I'm not confusing energy with intensity, but in a silly moment I got the word "photoionization" with photodissociation/photolysis. Yes, you need hard UV to actually eject an electron from its atom, but you need far far less energy to break bonds and damage DNA. Photosynthesis is all about redox driven by blue and red photons. These are more than just bond rotations (with only slim exceptions, bond rotations have the same energy state) from photostimulation. You can flip cis/trans bonds (main mechanism of retinal), ring closing in vit D, and cause all kinds of increased free radical activity [1]. In particular, blue light interacting with certain chemophores, such as catechins, are relatively prone to photoactivation [2]. Ever seen polycarbonate that's been around blue LED light sources (not sunlight) for a very long time? It yellows. That's not "just adding heat", that's chemical bonds breaking. Transparent just means the entirety of the body can be bathed in light. [1] https://www.ncbi.nlm.nih.gov/pubmed/15797866 https://www.ncbi.nlm.nih.gov/pubmed/15797866 [2] https://www.ncbi.nlm.nih.gov/pubmed/29973539 https://www.ncbi.nlm.nih.gov/pubmed/29973539
- JabavuAdams 7y ago
  Thanks for the info! Apologies if I came across as patronizing. EDIT> cis/trans retinal -- should have remembered that
  - kortex 7y ago
    No problem. At the time I was particularly sloppy with my terminology and that didn't help discourse much.
    - JabavuAdams 7y ago
      Is there some way I can contact you? I'm curious to learn more about how you know/learned chemistry. Contact details are in my profile. Thanks.

kortex 7y ago

I'm not confusing energy with intensity, but in a silly moment I got the word "photoionization" with photodissociation/photolysis. Yes, you need hard UV to actually eject an electron from its atom, but you need far far less energy to break bonds and damage DNA. Photosynthesis is all about redox driven by blue and red photons. These are more than just bond rotations (with only slim exceptions, bond rotations have the same energy state) from photostimulation. You can flip cis/trans bonds (main mechanism of retinal), ring closing in vit D, and cause all kinds of increased free radical activity [1]. In particular, blue light interacting with certain chemophores, such as catechins, are relatively prone to photoactivation [2]. Ever seen polycarbonate that's been around blue LED light sources (not sunlight) for a very long time? It yellows. That's not "just adding heat", that's chemical bonds breaking. Transparent just means the entirety of the body can be bathed in light. [1] https://www.ncbi.nlm.nih.gov/pubmed/15797866 https://www.ncbi.nlm.nih.gov/pubmed/15797866 [2] https://www.ncbi.nlm.nih.gov/pubmed/29973539 https://www.ncbi.nlm.nih.gov/pubmed/29973539

JabavuAdams 7y ago
Thanks for the info! Apologies if I came across as patronizing. EDIT> cis/trans retinal -- should have remembered that
- kortex 7y ago
  No problem. At the time I was particularly sloppy with my terminology and that didn't help discourse much.
  - JabavuAdams 7y ago
    Is there some way I can contact you? I'm curious to learn more about how you know/learned chemistry. Contact details are in my profile. Thanks.