Daily blue light shortens lifespan, causes brain neurodegeneration in Drosophila

Re:Daily blue light shortens lifespan, causes brain neurodeg... by JabavuAdams on Sunday October 20, 2019 @10:26PM (#21308897)

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.

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Re:Daily blue light shortens lifespan, causes brain neurodeg... by kortex on Monday October 21, 2019 @09:42PM (#21319577)

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

[2] https://www.ncbi.nlm.nih.gov/pubmed/29973539

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Re:Daily blue light shortens lifespan, causes brain neurodeg... by JabavuAdams on Tuesday October 22, 2019 @11:35PM (#21330815)

Thanks for the info! Apologies if I came across as patronizing.

EDIT> cis/trans retinal -- should have remembered that

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Re:Daily blue light shortens lifespan, causes brain neurodeg... by kortex on Wednesday October 23, 2019 @09:03PM (#21340680)

No problem. At the time I was particularly sloppy with my terminology and that didn't help discourse much.

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Re:Daily blue light shortens lifespan, causes brain neurodeg... by JabavuAdams on Thursday October 24, 2019 @06:32AM (#21343208)

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.

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