activity concentrations were observed to increase rapidly and to decline slowly throughout the residence time of persons at Rongelap and Utirik Atolls (Co75, Le80b). we These observations led to the selection of a declining continuous intake model. An exponential decline in the amount of activity ingested each day from the dietary sources was assumed. (Le80b). The following general equations were derived They may be applied to each muclide of concern: uv s AP° = _ X.k. ivi f, on ikjok ° ' , e -C0+k)t or . Ap? £} (rz ~(htks)t 1 qa (2iXi € e “(Atk t iy} -CAtks)t } Xi (eT AtKIE . e (ATK E)) i ks-k (2) , where t = time post onset of intake (time from day of return of each atoll population), d, X = instantaneous fraction of atoms decaying per unit time, d initial daily atom ingestion rate on day of return, atoms s a * p° , ‘, instantaneous fraction of atoms removed from compartment i in the body by biological processes, d “, X. = compartment i deposition fraction,