Could some one help me with these questions for the nuclear science merit badge:what is medical radiation and?

Radio waves and light are non-ionizing radiation, but ionizing radiation destroys tissue, so we often focus it on to a tumor to kill the cancer cells. Food is sometimes treated with radiation to kill organisms that cause decay. It will then keep for months without refrigeration. It is often not labeled, but if you find milk not refrigerated in the store it has likely been irradiated. Radio active isotopes are found in tiny amounts, in many things, including our air. This and other ionization that comes from space and our Sun is called background radiation. Radon gas is one of the components of our background radiation. When radon is more than about one part per million in our breathing air it is considered a cancer risk. Neil