Hto, Tritiated Amino Acid Exposure and External Exposure Induce Differential Effects on Hematopoiesis and Iron Metabolism
Résumé
The potential increase in tritium release from either nuclear reactors or new facilities such as the ITER reactor raises questions about the reliability of current ICRP and WHO recommendations about tritium exposure to human populations. In order to study the potential toxicity of tritium at the regulatory level, mice were chronically exposed through drinking water at three concentrations of tritium, 10 kBq.L-1, 1 MBq.L-1 and 20 MBq.L-1, in two different forms, either HTO or tritiated non-essential amino acids (TAA). After one month exposure, a dose-dependent anemia was evidenced, in association with an iron deprivation, in all TAA exposed groups, but not in HTO exposed groups. This anemia was compensated after eight months of exposure through an increase in mean globular volume, demonstrating the occurrence of an iron deficit-associated anemia (IDA). The analysis of hematopoiesis, of red blood cell retention in the spleen and of iron metabolism in the liver, the kidneys and the intestine suggested that the iron deficit was associated with a defect in iron capture in the intestine. By contrast, mice exposed to external gamma irradiation at equivalent dose rate during either one or eight months did not show any change in red blood cells numbers, white blood cells numbers or iron concentration in the plasma. Overall these results demonstrate that health effects may appear with chronic exposure to concentration of tritium above regulatory levels, but these effects are dependent upon the speciation of tritium.
Domaines
Sciences du Vivant [q-bio]
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