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The z3zTh concentration in rib bone from 38 humans ranged from <0.1 to 72 ng/g ash. Values increased with age and were fitted by the expressionwhere Y is the 232Th concentration in ng/g bone ash and T is the age in years. Evaluation of the retention of the zzsRa produced by the decay of23zTh is not possible for human exposure to environmental sources since direct intake of naturally occurring zz8Ra is too large.

A simplified radiochemical method has been developed for quantitatively analyzing radon gas in underground uranium mines. In this method, a measured volume of air is drawn by a pump through a drying tube and a cartridge containing dioxygenyl hexafluoroantimonate reagent. Radon is captured as a nonvolatile product. After radioactive equilibrium has been established between radon and its short-lived daughters (approximately 4 hours), the gamma-emission of the cartridge is measured with a scintillation counter. The amount of radon is then calculated from the gamma-emission rate. The effect of cartridge geometry, reagent load, and air flow rate upon collection efficiency and counting efficiency is reported.