- 21 . To these comments, * referenced by Geesaman, can be added the comments of Dr. A. B. Long: *. . . there is an urgent need to dispell the sense of ° security and certainty that the present limits for the maximum permissible lung burden and the maximum permissible air concentration bring . .. the public should be informed of the uncertainties that exist in these limits."?¢ V. . Biological Data Related to Cancer Risk from Insoluble ' Plutonium Particles We have shown that insoluble alpha-emitting particles result in intense but localized radiation. They can irradiate at very high doses without being organism- or organ fatal. We said that the available biological data strongly suggests that a DF=1 grossly underestimates the DE for insoluble particulates of Pu-239, and consequently, the derived standards ‘MPLB and MPC, for this radionuclide are greatly in error. We now turn to the experiments involving cancer induction ->-_ \ by intense local exposure, since these are especially relevant in judging whether or not insoluble alpha-emitting particles constitute a unique risk. Geesaman collected and analyzed the pertinent experiments, and what follows 32/ Long, A.B., Op, cit., p. 73.