Tritium levels in milk in the vicinity of chronic tritium releases
Résumé
Tritium is the radioactive isotope of hydrogen. It can be integrated into most biological molecules. Even
though its radiotoxicity is weak, the effects of tritium can be increased following concentration in critical
compartments of living organisms. For a better understanding of tritium circulation in the environment
and to highlight transfer constants between compartments, we studied the tritiation of different agricultural
matrices chronically exposed to tritium.
Milk is one of the most frequently monitored foodstuffs in the vicinity of points known for chronic
release of radionuclides firstly because dairy products find their way into most homes but also because it
integrates deposition over large areas at a local scale. It is a food which contains all the main nutrients,
especially proteins, carbohydrates and lipids. We thus studied the tritium levels of milk in chronic
exposure conditions by comparing the tritiation of the main hydrogenated components of milk, first,
component by component, then, sample by sample. Significant correlations were found between the
specific activities of drinking water and free water of milk as well as between the tritium levels of cattle
feed dry matter and of the main organic components of milk. Our findings stress the importance of the
metabolism on the distribution of tritium in the different compartments.
Overall, dilution of hydrogen in the environmental compartments was found to play an important role
dimming possible isotopic effects even in a food chain chronically exposed to tritium.