. . id f I- 150 n) of particics deposited (that is those emitting seve ‘al thousand neliuin nuctei pur day}. This is reasonable. “There would be sormetl ing like a thousand of baese partictes ana1 cach would chronically expos e 1 to 20 alveoli to intense cancer is like 1 in 18, 009 fer one disruptive par- ticle, then the total risk in this situation is one in ten, i-e., one man in ten y. wld develop lung cancer. Put another way, about 1 cubic centimeterof the lung is receiving hich doses of radiation. It would not be surprising if intense exposure of The question is: er such a localized volume led toa cancer one time in ten. if the individual volumes are, separated from each other, is substantial protection afforded? No cone knows. - It is :auch easier to find two cancers wil goo expusures of 1 cusic centimeter cach, thanit is to find a coupl - of cancers in 50,000 sinsle particle exposures. Certainly the length scales ‘> _of injury are long cnough that a disruptive carcinogenic pathway cannot be disregardedfor isolated hot particles (Gcesaman, D.P., 19G6&b). . ~s One can lock to the relevant experience for reassurance. In an ex: sriment done at Hanford by Dr. Bair and his colleagues, bea . > a Sem . - were given Pu22%G5 lung burdens of a few hundred thougandths of a gram y (Rair, W.J.,:et al., 1966; Ross, D.M., 1987). At 9 years post exposure, or after roughly half of an adult beagle life span, 22 of 24 deaths involvea lung cancer, usually of multiple origin. Wive dogs reiein alive. For comperison, these exposures are about 1090 timos larger than the present asta peroissiole burdens te ran. Vhere are Geo unsuiicheetory azpoets of luis expoeriinent. Mer.%. oD deavtyl ist a. Bo ayas ee ate sae i ree TR? ORICON vent * st Beth Ne Eenzeonr steer Os aa. va 380 ren, ER TS,as oe ex6a . firat,