In The Rffects af Nuclear “Neanans, it is noted that: “. . . internal sources of . . . heta particles, or soft (lov-energy) gamma-ray emitters can dissipate their entire energy within a small, possibly sensitive, volume of hody tissue thus causing considerahle damage." (51 np, 604-5) The implication of the above statement denotes an area ahout which there was much controversy during the discussion about radioactive fallout and its effects in the United States, Many scientists described dosage and exposure in terms of averages, e.q., the maximum permissable concentration (MPC) of strontium 90 allowable in the body of a worker in atomic industries. This is 1000 "Sunshine Units" which is 1000 micromicrocuries as uuC--one millionth of a millionth of a curie, a small unit of radioactivity) per total weight of calcium in a person's body. Since the average person has 1000 grams of calcium in his bodv, it equals 1 uuC per qram, maximum permissible concentration for the general population working in atomic industry) The equivalent (those not is 1/l0th of that, or 100 "Sunshine Units.” There are also other ‘PC's for other radionuclides. Nee ED (abbreviated what this averaging does not indicate, hovever, is the fact that strontium, like other isotores, not only selectively concentrates in certain tissues or organs, but that This means that owe TeRE?BT its distribution in these areas is now alvavs uniform, it is possible for a worker to have a total concentration in his tody or an organ of less than, or emual to the MPC of strontium, but that because it is unevenly denosited, he may have high concentrations or "hot spots" * : . . where the “PC of 1 micromicrocurie : . : (or 1/10 of a micromicrocurie) for each gram of calcium is exceeded, 90 . Thus gamma and heta-emitters like sx°°, cst? 37 and I 131 4. : which selectively *The term MPC since that time has been changed to Recommended Permissible Corcentration (RPC), 21 Danan 3°