Which form of electromagnetic energy is more damaging to tissues?

Answer 1

At frequencies above visible light, we have in progression ultra-violet, x-ray, and gamma regions. These are all harmful, and get more so the higher the frequency. We get ultra-violet from the sun, and this causes sunburn which is uncomfortable and can have long term effects like skin cancer. X-rays have to be carefully controlled for medical use, and gamma radiation should always be avoided by shielding.

At lower frequencies than visible, infra red is not harmful, but then we come to microwaves which cause heating in tissues because they stimulate water molecules to vibrate and get hot. Beyond that, TV and Radio waves are not thought to be harmful, though I think the jury is still out on cellphones, the holding of one close to the brain while transmitting might be damaging, especially to children.

Answer 2

Gamma rays