Exposure to radiation can take two forms. There are natural and artificial sources of irradiation. 87% of radioactivity comes from natural sources.
Exposure to radiation can take two forms: irradiation and contamination. With irradiation, the organism is subjected to a source of radiation which is often external (cosmic rays, X-rays, etc.). However, it can also be internal (within the body) when a radioelement is absorbed by the organism. With contamination, radioactive particles are deposited on the skin or clothing. These particles can also be inhaled or ingested. Irradiation is comparable to solar radiation. To protect ourselves, we move to the shade or open a sunshade. Contamination is like rain. To protect ourselves, we dress in waterproof clothing.
There are natural and artificial sources of irradiation.
Natural radioactivity has two origins: cosmic and terrestrial. Cosmic radiation is radiation from outer space. Cosmic radiation has been bombarding the earth constantly for billions of years. The other source of radiation is the ground itself. This radiation depends on the type of soil. Doses are higher in granite regions, such as Brittany, the Massif Central and the Ardennes. Each and every one of us emits radioactivity. Man is naturally radioactive.
Artificial radioactivity. Artificial radioactivity was born in a laboratory when Irène and Frédéric Joliot-Curie developed phosphorus-30 - a radioactive element that does not occur in nature - in early 1934. Since then, several hundred radioelements have been produced, of which around 30 are useable for scientific and industrial purposes. Medical uses account for nearly all of the artificial irradiation to which we are subjected during our lives. Doctors soon took an interest in the discovery of radioactivity, leading to the birth of radiotherapy (the therapeutic use of radiation) and later nuclear diagnostics (the use of radioactive tracers).
