Radiation always has damaging affects on the body. But, when used in a controlled manner, it can be used to treat diseases like cancer. The mechanism involved in treatment is the same damaging effect on the cancer cells. So, the radiation works only by damaging effects like
1. Ionization of water molecules in the cell.
2. changes and aberrations in DNA.
When radiation incident on any tissue or organs in the body, the region or part is subjected to intense heat. This is due to high energy levels in the radiation particles. Once, the heat is sufficient, the molecules inside the cells and tissues get altered chemically.
This leads to formation of abnormal structures, protein denaturation, chromosomal changes etc. All these changes are detrimental to the health of the cell. So, the cells undergo programmed cell death (apoptosis). This is to limit the spread of abnormal molecules into neighboring cells.
However, regular exposure to radiation will lead to damage of all the exposed cells.
Even though some cells survive, they would be bloated or abnormal. Sometimes, they can lead to development of new cancers.
Other times, the chromosomal aeration would pass on to progeny of the person exposed. This leads to disabilities in their children. Hence, such effects were seen in people who lived in regions due to atomic destruction
So, the secondary effect of radiation treatment could be formation of cancerous cells. But this is also eliminated due to chemotherapy given after radiation.
In sterilization: The same principle is applied in sterilization of heat and water sensitive materials. However, here non-ionizing radiations are preferred as large area like a container of packaged material is exposed. This non-ionizing radiation is also less harmful to the technical personnel involved in the procedure.
So, in short radiations works by
- Increasing the internal heat of material
- ionizing the atoms of the matter.