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.
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.