ee ve ce cpee ee eee, sm SECTION |. * RADIATIONS Po A. GENERAL BACKGROUND INFORMATION JF }. Natural Background and Medica! Exposures As far as is known, man always has and always will liveina is environment filled with nuclear radiation. There’are:radioactive materials present naturally in the ground,the sea, and inthe air, Cosmic rays bombard us frum outer apace. ‘Naturally. occurring radioactive materials in our food supply irradiate us a? fee ny f 5 ra wf 4 | "hh | Hs | | le 4 aay SRelYR BDee we a i + Ya fa “a : 2 a nae. rh wee « a tantlens gee . —y se, we, me eet ee vas ’ ON ae . . zi) from within. To these leyels of radiation exposures are now added ‘those from fallout—but these radiations (gamma rays and‘ beta par-~ ticles) are no‘different in kind from those emanatingfrom; natural sources. Noris there any evidence that they produce: any fundamentally different biological effects. The radiations from naturalsources and from medical, induatrial, and ecien-. tific uses of. radioisotopes and X-ray machines, and ‘their bi-; olugicai effects, have been studied intensively for many years. To repeat, radiation exposures from fallout are in addition to. those from natural sources but they are just that ~ additions of. more of the same type of radiation. Fallout has not introduced a new and strange agent into our environment with completely: unpredictable results. Indeed, a Committee of the Nationa), vironmental hazard... .”"? Academy of Sciences-National Research Council has stated: “ ... Despite the existing gaps in our knowledge, it is abun-dantly clear that radiation is by far the bast understood en- TABLE 1.—Radiation Exposures from Natural Background ond Medirat Sources Natural Vackground (annual exposures) Total vececeseecres Gamma rays (from iv-rreatrial sources) and voumic rays Potassium 40 (internal Cauiben J4..... Midieuw! Rrpueures Chest X-ray (per exposure) Back Xray (perexposrep Photofuerogram (per eocposure: finotre ditention) serie . . a Lc teers veers cieegee veugeees sg but | ebboent Hoentgens 0.085- 0.20 0.1 (varies), O O18 (varies). 0.00] 42 ad wr 20 30,