[kortex]

Blue light has more energy per photon (energy is proportional to frequency). Therefore, it is better at ejecting photons from atoms and damaging molecules than other visible light. UV is even worse.

Also, semi-related, eyes are less sensitive to blue light, so if you want to achieve the same effective perceptual brightness, you need more photons if it's a higher color temperature.

[ekianjo]

Kind of nitpicking, red light energy is around 2eV, while for blue light around 2.5eV, it's not like it's a very sensitive difference.

UV is much higher energy, in the range of 40 eV~.