Central values and an estimate of the variation about the central values are given for 24 trace elements and the dry, and ash content of samples of 29 different tissues of 150 adult victims of instantaneous death who had spent their lives in the United States.

The concentrations of trace elements in normal human tissues and the distribution of these elements throughout the body have been determined by emission spectroscopy. The methods of collection and preparation of samples, of spectrographic analysis, and of statistical treatment of data are describcd.

Central values and an estimate of variation about the central values are given for twenty-four trace elements and the ash per cent of dry weight of samples of ten different tissues of 162 adult subjects from outside continental United States. When groups of adult males from different geographical locations were compared, "essential" elements showed little aeographical variation but those elements for which no role is known showed significant ---geographical difference.

The dose rates and annual doses of individuals continuously exposed to radioactive material in the environment will be approximately proportional to the concentration of the radionuclide in the various tissues of these individuals. A stable isotope of the same element should have a similar distribution in these tissues, and thus the form of the distribution of the annual dose or dose rate may be inferred from studies of the distribution of concentrations of stable isotopes in human tissues. Statistical methods given by BRUNK and MASSEY have been applied to data for normal isotope distribution in human tissue as reported by TIPTON et al., BRYANT et al. and KULP et al. The method by BRUNK determines a band such that at each concentration value one may assert with 95 per cent confidence that the true distribution function lies below (above) the upper (lower) boundary of the band. The method by MASSEY has been applied to obtain a 95 per cent confidence band for the entire cumulative distribution curve. In the majority of cases studied one may assert with 95 per cent confidence that not more than 5 per cent of the population groups sampled have concentration values above three times the sample mean, thus providing some quantitative interpretation of the assumption used in the reports of the-Federal Radiation Co;ncil.

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