UPTAKE OF FALLOUT RADIONUCLIDES BY MAMMALS
AND A STOCHASTIC SIMULATION OF THE PROCESS
FREDERICK B. TURNER
University of California at Los Angeles, Los Angeles, California
ABSTRACT
A deterministic model, designed to predict time-specific levels of
1317 in the thyroids of herbivores as a function of '*"I on vegetation, was
revised as a probabilistic simulation of the experience of a consumer
in a fallout field. The stochastic model was used to generate synthetic
populations of up to 1000 individuals. The frequency distributions of
thyroidal ‘4 in 24 of these hypothetical populations were analyzed in
terms
of
the
recommended
assumption
of the
Federal Radiation
Council, namely, that the majority of individuals in a population does
not vary from the average by a factor greater than 3. In only two of
the distributions
times the mean.
The
did more than 2% of the population exceed three
frequency
distributions
predicted by the model were all
skewed to the high side and approximated lognormal distributions. A
number of frequency distributions of radionuclides recorded in the
literature were reviewed, and X’ tests indicated that most of them
were not normal, All the non-Gaussian distributions were skewed to
the high side, and some of them were apparently lognormal. It is concluded that the general form of the synthetic distributions produced by
the model is in agreement with most past observations. It is further suggested that such asymmetrical distributions may be more
likely than normal ones. The implications of this possibility, in terms
of health physics, is discussed.
Consideration is also given to the possible relation between the
frequency distribution of a radionuclide in diets and the frequency
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