Transport of Radium Sulfate from the Lung and Its Elimination from the Human Body Following Single Accidental Exposures

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Abstract
In the presence of insoluble radioactive dust, it is not always possible to determine whether the permissible level in air should be governed by the radiation delivered to the lung and air passages or by the radiation delivered to the critical organ where ultimately most of the radioelement, mobilized from the lung but not excreted by the body, will be deposited. This perplexing situation is created not so much by lack of knowledge of the fraction deposited in the various parts of the respiratory tract (1–3) as by the scarcity of information on the rate of elimination of the particulate matter by the human lung. This statement applies not only to the recently discovered artificial radioelements but extends also to radium, which as early as 1926 was shown by Reitter and Martland (4) to gain access to the skeleton by way of the lungs. In order to gather information on the subject, six individuals exposed to radium sulfate dust as a consequence of two industrial accidents were selected for study. Five persons (R., K., Ch., Ca., and S.) from the first accident (5) have been studied for a period of a year, through the collaboration of Dr. Eugene L. Saenger of the Cincinnati General Hospital; the sixth, technician G. from our laboratory, has been followed more closely for 250 days and will be under observation to the limit of our resources in sensitivity. In both instances the inhalation lasted for only a few minutes following the rupture of 50-mg. radium capsules containing approximately equal parts of RaSO4 and BaSO4. This study is based on the following observations: (a) exhalation rate of radon, (b) measurements of gamma-ray activity from the whole body, (c) measurement of gamma-ray activity from the thorax, and (d) measurement of radium in the excreta. It has been possible to estimate from a and b the total-body burden according to accepted practice, and to gain by means of procedure c some information as to the localization of the RaSO4. Owing to difficulties of a practical nature, a complete excretion study was feasible only in the case of our technician; only scattered data are available for the others. The Body Burden The quantity of radium in the body which produces radon at the rate exhaled by the host can be computed by the expression: This fraction does not contribute to the measured gamma-ray activity and it is, therefore, added to the latter in the estimate of the total radium burden. After appropriate trapping of water, and through a continuous process of adsorption, all the radon contained in the air exhaled by a patient in ten-to twenty-minute periods was collected on charcoal. The radioactive gas was then transferred into suitable ionization chambers connected to an electrometer, and the calibration was performed by comparison with the ionization produced by known fractions of Rn liberated by standardized radium solutions.
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