DIETARY INTAKE OF RADIONUCLIDES
889
magnitude to offset the higher “Sr levels experienced during these
months. The highest intake levels generally occur in the Northeast,
followed by the North Central, South, and Western areas. However, in
1962 the South had the highest Sr intake from milk.
In a consideration of some of the variables influencing radio-
nuclide intake (from the various food-consumption estimates to the
differences in milk consumption arising from geographic area, age,
and
seasonal
influences),
it
is obvious that much of the information
needed to assess radionuclide intake accurately is lacking. Thus our
current estimates of radionuclide intake may only be considered as
conditionally acceptable on a general population basis. We have no
real indication of the range of values actually encountered, and it is
this range, particularly the upper portion of it, which is of major importance. This is especially true since there is a general concensus
that we are not currently at dangerous levels on a population-wide
basis, If this follows, then we should know just how close the upper
range of actual intake approaches a level of concern or, conversely,
how much above our present evaluation of contamination are some
groups of the population. It may not be critical at this time to know
the bounds of our estimate for some radionuclides, but, if nuclear
testing should resume or accidents should occur, we would need this
information.
ALTERNATIVE METHODS OF ESTIMATING 9°Sr-INTAKE LEVELS
In an attempt to refine the process of estimating Sr intake without accurate and up-to-date food-consumption data, an Observed Ratio
(OR) study based on urine/diet levels has been proposed. Such a study
would investigate the relation between the Sr/calcium ratio in the
urine to the Sr/calcium ratio in the diet. Among the advantages of
such a study are the following:
1, Urinary samples reflect total %Sr and calcium that enters the
body. Thus there would be no need to estimate the contributions of
various foods, and no food-consumption data would be needed.
2, Sudden changes would be quickly detected.
3. Sampling and bulking would be relatively simple.
4, Results could be classified in many different ways.
5. Time patterns of accumulation and dose estimations could be
obtained,
Several studies in this area have already been conducted in conjunction with field nutrition studies!® or in metabolic wards.'4:® However, in each of these investigations, the pooling of urine has precluded
an examination of individual variations that may influence the sampling