Ff) s e ’ ay tS 5 Pn) 7 + * rw pe ¢Ch u“ t v 5 we 73 CONCLUSIONS Barcngrounc exposure rates may be accurately reconstructed fron carelul anaivses of soil gamma emitters and the contribution ef cssmic cays. In situ moasurements of exposure rates will reflect significant contributions above bacxground of fallout of tne uranium and thorium cnains can be ignored. It is intuitively obvious that a continuum éxists geographically between areas which received worldwide and tropospheric fallout anc those wrich received only stratospheric fallout. The Cor worldwide) 1 hibit this islands of Micronesia exhi continuum such that beyond about five hundred kilometers from the test sites it may D2 impossible to distinguish between the contributions to contemporary environmental exposures from U. S. Pacific nuclear tests and those attributable to multinational worldwide f™, fallout.