The effects of microwave energy upon animal or human tissue are those associated with heating. Microwave energy is non-ionising and as such is free from the cancer risks associated with ionising radiation such as X-Rays. Tissue subjected to high levels of microwave energy is likely to suffer severe burning.
Tissue most susceptible to damage from exposure to high levels of microwave energy are the lens of the eye, with a risk of cataracts, and human / animal sperm.