Gastro intestinal absorption of neptunium by monkeys, influence of the diet on said absorption

Long-lived γ-emitter neptunium 237 has recently attracted increasing attention due to its long-term role in the administration of radioactive waste materials. In studies concerning the radiological impact associated with the rejection of said wastes, the potential doses carried by neptunium have been calculated by assuming that 1% of this element is absorbed at gastrointestinal level. This transfer-coefficient value (f1) has been used since 1980 by the ICRP as published in its publication No. 30. However, the data taken into account at the time of establishing this coefficient came from experiments in which large amounts of neptunium have been employed. Since then, utilizing ingested smaller quantities, it has been found that the transferred amount is about 10 times smaller. The influence of the diet on the value of f1, having been demonstrated in the case of plutonium, we examined whether the same is applicable for neptunium in the case of baboon, a primate similar to humans