Radiation is all around us. It was present from the time the earth formed and has been here ever since. Natural radiation is found in everything we use and in the world around us. Applying this information we can determine the age of ancient artifacts. In living creatures, we can use radioactive elements as tracers. Living organisms consume food that contains radioactive materials. Tracers, such as carbon-14 reach an equilibrium within the organism. When the organism dies, the equilibrium between the environment and the organism ends. Since all radioactive materials by definition have a constant rate of decay, by determining the amount of activity present in the remains of the organism, the point at which it left equilibrium (death) can be determined.
The understanding that everything around us contains radioactive material to some degree is often limited in members of the public. Radiation is commonly held to be dangerous in any dosage. While this holds true for high levels, the low level effects are difficult to measure. Some investigators feel that small amounts of radiation may be healthful. This concept that small doses of radiation may be healthful is termed hormesis.