No abstract

The weights of 762 normal thyroid glands dissected at autopsies in New York City indicate that the mean adult thyroid weighs 16.7 f 6.9 g. The thyroid weights are distributed log-normally. These mean values are lower than the values described by other workers or used in standard dose measurements. The data suggest that 1 per cent of New York residents have thyroids that weigh about one-third of the mean.Data are also presented on a series of fetal thyroids in which the weights varied from 20 mg at the third month of gestation to 1.5 + 0.6 g at full term.

Management of the public health aspects of generalized environmental contamination by 1131 requires that estimates be made of the mean thyroid dose received by a given segment of the population. Some measure of the distribution of doses around the mean is also desirable.It is possible to estimate the absorbed dose to the thyroid gland by analysis of post-mortem material, by in viuo measurements of a sample of the exposed population, or by calculations based on environmental data. When the exposed population is so small that meaningful data can be obtained on a sample of manageable proportions, in vivo measurements are highly useful. However, when the exposed population is a substantial part of the country, as in the case of fallout associated with the testing of nuclear weapons, it is impractical to obtain reliable estimates of the distribution of thyroid dose because of difficulties of obtaining a representative sample and because of the logistic problems associated with this type of measurement.The problem of calculating the distribution of doses based upon knowledge of environmental factors is simplified by the fact that fresh cow's milk is known to be the principal route by which 1131 is absorbed. This paper discusses the mathematical relationships that determine the distribution of thyroid doses in the exposed population and discusses the feasibility of undertaking such calculations based on both existing data and data yet to be obtained.