878
THOMPSON AND LENGEMANN
calcium in the diet, averaged 0.97 + 0.08 for a group of normal subjects on normaldiets for a 17-day period.
The determination of accurate estimates of radionuclide-intake
levels is Of vital importance if we are to determine the hazard from
such radionuclides. The lack of this information can leadto uncertainty
and hesitation during accidental releases of ra‘tioactivity or during
accelerated nuclear-testing programs.
INTRODUCTION
The shortcomings of our procedures for estimating radionuclide
intake were emphasized by the events following the 1961-1962 nucleartest series. Although most of the confusion was centered around the
estimates of '4I intake, it was the inadequacy of certain basic data
needed to properly interpret '*4l analyses which caused manyof the
problems.
The basic data were missing because there were no net-
works biologically oriented to investigate the relations among air concentrations, ground deposition, pasture contamination, uptake processes, and milk distribution and processing operations and the
ultimate consumption levels by various components of the population.
The lack of this information made estimation of '*I intake extremely
difficult and the results controversial. In addition, there were un-
certainties because of differences in uptake associated with age as
well as the possibility that certain groups of people obtained measurable
quantities of '*4] from nonmilk sources.
These uncertainties are similarly important in regard to the other
radionuclides of concern in the human diet. Little is known of the differences in food intake and how its pattern may vary geographically
Or economically. No monitoring networks have been developed to
follow radionuclides completely through the food chain to examine the
interrelations that influence the uptake of these radionuclides. During
the present moratorium it seems appropriate to develop such techniques and td quantify the relations in a manner that will provide accuracy both now and in the future should the need arise. Such action
would alleviate the confusion experienced in the pastin initiating plans
designed to cope with levels of radionuclides thought to be too high for
continued ingestion of the foods concerned.
In an attempt to show the nature of the variations in radionuclide
intake, the emphasis of this paper is directed toward changes in food
consumption and the resultant effect on radionuclide-intake levels.
Strontium-90 will be used as the radionuclide in these comparisons,
but many of the sameprinciples apply to /*"Cs and to the shorter-lived
radionuclides if consideration is given to the shorter half-lives.