~ 28 The permissible concentrations of radioisotopes in sea water -- not in drinking water -- were calculated by Carritt et al. in Publication 655 of the National Academy of Sciences - National Research Council (1959). The purpose of making the calculations was to establish a limit for the concentration of radioisotopes in sea water, so that the uptake of radioisotopes by fish living in the water would be less than the MPC value for fish. The permissible sea water concentration (PSC) for any one radioisotope was calculated by dividing the MPC value for fish by the factor by which the fish concentrated the isotope from sea water. The ratio of water intake to fish intake that was used in the Carritt report was 10, stated in the the same as above. report in this form, PSC - Although not (MPC)f concentration factor where (MPC)f is the value for (MPC)wy corrected for the agifference between water and fish intake and is obtained by multiplying (MPC)w by the ratio of the calculated water intake (2.2 kilograms) to the actual fish intake. A partial permissible concentration value for seafood for radioisotopes to be expected as waste from the operation of nuclear- powered ships has been calculated by Revelle et al in ’