to support the linear theory.* Proponents of the linear theory, however, pointed out that evidence for threshold response was not sufficient to definitely prove there was such a thing. Much of the debate over the linear versus threshold theories results from the establishment of Maximum Permissible Concentration (MPC) as mentioned in the Internal Exposure section. established on a basic assumption: for radiation; that is, The MPC for human beings is that there exists a threshold effect there is an amount of radiation above normal background radiation which human beings can absorh and which will not cause harmful effects (or effects so small as to he able to be tolerated). Dr. U,L. Friedell., of the School of Medicine at Western Reserve University, testified before the U.S, Congressional Subcommittee thusly: "At the very low levels where the levels begin to approach the natural levels we are facing, I think there is grave uncertainty. This, of *An interesting, entertaining tour de force diatribe against the linear theorv by one Alden Potter appears on pages 1987 to 1996. Mr, Potter attacks many commonly held scientific concepts in biology, genetics, statistics and mathematics to allege that there is indeed no linear experience in nature, A simplication of his reasoning is that we see threshold relationships all throughout nature; nature is ordered by certain basic, unchangeahle laws and thus radiation effect must, nature, too, be of a threshold He states as an example: "But if sensory equipment has its thresholds, living conditions are also narrowly restricted to those prevailing in the so-called biosmhere, Some heat is essential; much more or less, is lethal, It's a case of not crossing a threshold and getting too much of the good things of life; including life itself ... . Then there are the trace elements, which is toxic. essential to plant growth, an excess of In short, there is no such thing as a ‘linear’ relation hetween life and the elemental forms of matter and energy. & threshold is the very essence of life." What this reasoning does not take into account is: 1, Human tolerance to the effects of radiation may he possilly so low but for all practical 37 5010301