.= a § Another point that should be made in this connection is that the bio= logical information upon which our aexie mum permissible exposure levels are large~- ly based, have been nlmoct entirely derived from experimentation from fourteen MEV neutrons and less. The Commission 4g now in the pro@cess of erecting an accelerator at Brooke haven which will achieve twenty-five billion electron volt protons, There are several accelerators and a half dozen or so in the two hundred and fifty to five hundred MEV range, synchro= cyclotrons and yet the biological informe tion on which our maximum permissible exe posures are based upon, experiments were done at a much lower energy. One can argue from physical consid~ erationg like linear energy*transfer and specific ionization that such extrapolation is admissible, But until the biological experimentation actually at these high ener gies is really done, it seems to us ve must regard this as simply scientific hypothesis that has yet to be proved. 97