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 mentioned in the Internal Exposure section. established on a_basicassumption: for radiation; that is, (MPC) as The MPC for human beings is Cr; that there exists a threshold effect aa ec I there is an amount of radiation above normal background radiation which human beings can absorb and which will not cause harmful effects (or effects so small as to be able to he tolerated). Dr. H,L. Friedell, of the School of Medicine at Western Reserve University, testified before the U.S. Congressional Subcommittee thusly: AEI wet. EPROCUCUIOREe - e "At the very low levels where the levels begin to aporoach 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 hy certain basic, unchangeable laws and thus radiation effect must, too, be of a threshold nature. 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 biosrhere, 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 qood things of life; including life itself. , ..Then there are the trace elements, essential to plant growth, an excess of which is toxic, In short, there is no such thing as a '‘linear' relation between life and the elemental forms of matter and energy. A 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 possibly so low but for all practical 37 Zi