237Pu experiments with the plaice Pleuronectes platessa

Some experiments have been made on the metabolism of ²³⁷Pu — a high specific activity, gamma-emitting isotope of plutonium — by the plaice Pleuronectes platessa L. Very little of the isotope was incorporated into fish after 2 months exposure to labelled water. The oral retention from a variety of labelled foods was also very poor, and apart from the gut itself no incorporation of the isotope could, in fact, be demonstrated. Injected ²³⁷Pu was eliminated very slowly, and some evidence was obtained for an inverse relationship between the rate of ²³⁷Pu loss and the rate of growth of the fish. Growing fish incorporated a relatively larger fraction of the ²³⁷Pu body burden into skeletal material, and this was attained at the expense of the isotopic content of the liver. Very little ²³⁷Pu was incorporated into muscle.