has been found that plutonium is now being taken up by the plants and animals in the New Mexico area after a delay of five (5) years.* The selection of pu2?9 by food organisms is important in as much as the permissible amount for humans in food or water is 3.3 d/m/g or cubic centimeter on a continued basis. Other fission product isotopes supposedly not avail- able by virtue of insolubility that should be studied are Ce £f. 144 , Pmt47 , and Ru 106 — 5 Soluble fission products such as sr? and cgi35, with long half lives, are still present at Bikini and Eniwetok. The very low maximum permissible amount of sr?° for humans increases the importance of a thorough survey of the amounts and locations of this isotope within the food chains in the contaminated environment. (The maximum permissible amount of sr?° in the food or water on a continued basis is 1.8 d/m/g or cubic centimeter. The total amount of sr?? to be permitted in the body is 6 millimicrograms.° U. S. Atomic Energy Commission report, UCLA~108 "Maximum permissible concentrations of radioisotopes in the air, water and in the human body." Subcommittee on Internal Dose of the National Committee on Radiation Protection. 1951. U. S. Atomic Energy Commission report, AD-325 (C).