It is now possible to discriminate between cancers caused by intake of a radioactive material and those that arise spontaneously

Recently, scientists from the Helmholtz Zentrum Munchen have identified a genetic change in thyroid cancer as a signature or fingerprint that points to a previous exposure of the thyroid to ionizing radiation.

Parts of Kerala and Tamil Nadu have high background radiation due to large amounts of monazite
We live in a sea of radiation.

Now it is official. In the January 2009 issue of the Health Physics Journal, researchers from the Regional Cancer Centre (RCC), Thiruvananthapuram, and their collaborators have shown that there is no excess cancer risk to people living in the area of high natural background radiation in Kerala from exposure to terrestrial gamma radiation.