-hthis vicinity would be acquired before the fish are taken from the water. Tms far, we have been unable to obtain any fish with sufficient radioactivity from this source to permit an approximate empirical determination of the external radiation level which would correspond to maximum permissible average concentrations in food and water discussed above. However, on the basis of the uptake of the various fission products by fish under other conditions, the Division of Biology and Medicine, 1].5.A.R.C., estimates that the criterion of 0.1 milliroentgens per hour at 5 cm is unnecessarily restrictive for this case. The radioisotopes sr®9, sr, and patho which limit the quantities of fission products which may be permitted on the ontside of the fish after they are taken from water are relatively unimportant in considering the radioactivity which may be permitted in the flesh of the fish, since these radioisotopes are not retained in the flesh. The radioisotopes taken up by the flesh, of which Ce137 is an example, have very mich higher permissible concentrations in food and water, of the order of 1 x 1073 microcuries per milliliter. From a fish weighing 50 to 100 pounds, the gamma radiation from a maximum permissible concentration of these radioisotopes in the flesh is estimated to be several milliroentgens per hour, measured at a distance of 5 centimeters from the fish. The actual radiation level will, of course, depend upon the size of the fish. DOS ARCHIVES