Contamination radioactive du milieu et radioecologie

Radioecology is defined as the study of the relationship between living beings and the radioactive environment, and includes the study of sources, nature of contamination of the atmospheric environment and the harm that results for man and natural ecosystems. The origins of radioactive substances in the environment are both natural and artificial. The natural sources include primary cosmic rays from space, interacting with the atmosphere to give secondary cosmic rays (such as ¹⁴C, ³H, ⁴⁰K, ²³⁸U, ²³²Th). Artificial sources include fallout from nuclear explosions, from nuclear power stations and from research using radioactive isotopes. The influence of ionizing radiation on animal and plant species is discussed. The responses are highly varied and include changes in growth patterns of irradiated organisms and higher mutation frequency. The transfer of radioactive compounds into the food chain is illustrated. An important difference between aquatic and terrestrial food chains is that terrestrial contamination can be directly incorporated into animal and human food. In the aquatic environment, radioelements are incorporated into substances dissolved in the water before incorporation into an organism. This leads to a marked difference in the speed and magnitude of incorporation into human food.