Terms and definitions that are helpful

Genotoxic
A term used to describe toxic agents that can cause mutations in genes (DNA). Known genotoxins include X-rays and other forms of radiation, some synthetic chemicals, and viruses. Since genes are passed down to the next generation, the damage induced by genotoxins can be inherited.
Mutations
Sudden changes in the genetic material of a cell. Mutations occur naturally at a low rate but may increase as a result of radiation, some chemicals, and viruses. Some mutations are beneficial but the majority of mutations are harmful.
Radiation
A stream of particles, alpha, beta, and/or gamma particles, from a radioactive source like X-ray or uranium.
Uranium
A radioactive element and is the mineral uraninite which also contains radium, thorium, polonium, lead and helium.
Plutonium-239, Radium-224, Radium-226, Radium- 228, Radon-222 and Thorium-232 and their decay products
These are classified as known carcinogens by the International Agency for Research on Cancer (IARC). X-rays and gamma radiation are also classed as known carcinogens by the IARC.
Half-life
The time it takes for half of the original radioactive material to transform into daughter products, which may or may not be radioactive.
Radium-226
Has a half-life of 1602 years
Radon-222
A radioactive gas. It is one of the decay products of radium 226. Radon occurs naturally particularly in the areas underlain by granite. In 2007, Health Canada changed the exposure action level for radon on “normal occupancy areas” from 800Bq/m3 to 200Bq/m3.