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Environmental water samples are routinely acidified before radionuclide analysis to prevent adsorption of radionuclides on the container walls. This study addresses the concern for volatilizing 99Tc from acid solutions during evaporation before beta analysis has been addressed. Water samples can be acidified to pH 1.7 with nitric acid and evaporated to dryness on planchets without significant losses of technetium due to volatilization. However, the planchets should not be flamed unless a detergent is used, and control samples should be flamed to determine the loss of activity under the conditions used.

Water and live molluscan shell samples were collected simultaneously at seven locations on the seacoast of the United States. Samples of silt, water, and shells from an estuary were also included in the study. The water samples were analyzed for U238, U234, calcium, and salinity; the shell samples were analyzed for U238, U234, calcium, and crystal structure. All water samples, regardless of salinity or total uranium content, were found to have uranium activity ratios, Au234/Au238, within the experimental uncertainty of the 1.15 value accepted for an oceanic environment. The results indicate that the normally higher uranium activity ratio of rivers does not increase the ratio of coastal waters above the 1.15 oceanic value. The activity ratios of all except two shell samples analyzed were similar to those of the surrounding seawater and to the oceanic 1.15 value. The application of the results of the study to the determination of geologic age via uranium-uranium daughter equilibrium is discussed.

A paper presented on Jul. 13, 1959 , at the Annual Conference, San Francisco, Calif., by Richard L. Blanchard, Asst. Sanitarian, Div. of Radiological Health, Occupational Health Field Sta., USPHS, Salt Lake City, Utah; George W . Leddicotte, Supervisor, Activation Analysis Group, Analytical Chemistry Div., Oak Ridge National Lab., Oak Ridge, Tenn.; and Dade W . Moeller, Chief, Radiological Health Training Activities, Div. of Radiological Health, Robert A. Taft San. Eng. Center, USPHS, Cincinnati, Ohio. This study was jointly sponsored by USPHS and Oak Ridge National Lab., and is based on the work performed by the authors at Oak Ridge National Lab.

In estimating the relative hazards created by the inhalation of thoron and thoron daughters, certain assumptions were required because of the incomplete knowledge of the biological behavior of these elements or were employed to simplify the calculations. These assumptions were that all daughters produced by the decay of thoron in the lungs were retained in the lungs until they decay to stable lead; the potential alpha energy of the daughters was calculated only from the energy released by the decay of ThB to stable lead; thorium A decayed 100% of the time to thorium B; thorium C was considered to decay 33.2% of the time by emission of 6.07 Mev alpha particles; and that only the tissue dose delivered by the alpha particles was considered. These calculations resulted in several interesting conclusions. They showed that veutilation is much more effective in reducing atmospheric concentrations of thoron daughters than it is for radon daughters. Conversely, practical rates of ventilation will not appreciably lower atmospheric concentrations of thoron. In comparison with radon daughters, much longer sampling times are feasible. This is important, as thoron daughter samples collected in the field will usually have quite small amounts of alpha activity and will requiremore » a more sensitive instrument than those which are satisfactory for radon daughter measurements. The calculations indicate that a concentration of only 8 mu mu c of thoron per liter at equilibrium with its daughters is equivalent in potential alpha energy to a concentration of l00 mu mu c radon per liter at equilibrium (1.3 x 10/sup 5/ Mev/1). At equilibrium the calculated lung radiation dose from thoron is insignificant compared to the calculated lung radiation dose from thoron daughters. For example, a concentration of 5360 mu mu c of thoron per liter delivers a lung radiation dose equivalent to that from a working level concentration of thoron daughters. The calculations also indicate that, on an activity basis, the permissible atmospheric concentration of thoron daughters should be much less than the level for radon daughters. Therefore, all situations involving the prceessing and use of appreciable amounts of thorium ores, salts, or metal should be surveyed to determine if significant amounts of these elements are present in the workroom atmosphere. (Public Health Engr. Abstr. 40 (1960) Dec.)« less

Radiological sampling and analysis performed under the National Interim Primary Drinking Water Regulations were evaluated for the U.S. Environmental Protection Agency (EPA) Office of Drinking Water to consider whether any changes should be recommended. The authors reviewed the analytical screening scheme; sample collection, storage and analysis procedures; selection of analytical methods; reliability of results; and possible future needs. The main problem in the program has been dependence on a screening scheme of gross alpha-particle activity measurement and 226Ra analysis for predicting elevated 228Ra levels to determine compliance with the maximum contaminant level (MCL) for Ra. In some aquifers, 228Ra levels have been found to be unrelated to 226Ra levels. Several alternatives are discussed to eliminate this problem. A secondary problem is that the measurement for assuring compliance with the MCL for gross alpha-particle activity minus Ra, Rn and U uses chemical U analysis and assumes equilibrium of 238U and 234U. Because some ground waters are known to be at disequilibrium, radiometric U analysis is needed for those gross alpha-particle activities and chemical U values that could result in an erroneous conclusion relative to the MCL. In addition, studies were recommended for determining analytical uncertainties and assuring reliable sampling and sample maintenance; improvements in the system for accepting methods were suggested; and methods were identified for several radionuclides not currently in the analytical program that may be needed to assure absence of elevated radiation doses and could be useful for identifying trace contaminants.

THE radioactive gas radon-222, produced by the decay of radium-226, diffuses from the ground and is transported by atmospheric turbulence far from its origin through the troposphere and into the stratosphere1. The radioactive decay of radon-222 and its short-lived descendants produces measurable quantities of lead-210 in the atmosphere1–3. Lead atoms so formed become attached to dust particles and eventually return to the Earth's surface, principally in rainfall1,4,5. Hill's4 report of a correlation coefficient of 0.87 between the quantity of rainfall and the concentration of lead-210 in grass clearly indicates a linear relationship. Holtzman6 reported a relationship between the concentration of lead-210 in the human skeleton and in the atmosphere. Whether the lead-210 enters the body principally through precipitation on foodstuffs that are later eaten5 or through direct inhalation, or by both means7, is at present uncertain. It is therefore feasible to view the occurrence of lead-210 as a “natural fall-out” product, similar, in this respect, to fission product fall-out, artificially produced from a nuclear detonation. In fact, very strong similarities between lead-210 and fission product activities have been reported with respect to their behaviour in the atmosphere1, to their rate and mode of deposition1,5, and to their concentration in grasses4. The similarities between lead-210 and fission product activities do not imply any relationship in their production. The formation of lead-210 in nuclear weapons explosions is improbable, and if any were so formed it would be negligible in comparison with the amount formed by natural processes8. The observed similarities between lead-210 and fall-out are caused by their similar behaviour in the atmosphere.

The thorium-230: uranium-234 method of dating corals and oolites has been evaluated in detail for reliability, and various criteria have been established. Reliable ages for extensive coral formations of about 6000 and 120,000 years were obtained. A hiatus in the development of coral between 6000 and 120,000 years ago on the Pactfic atoll of Eniwetok implies that conditions did not permit coral growth during this period. The record prior to 120,000 years ago is not clear, probably because of a lack of unaltered samples.

THE principal radiation exposure of a uranium miner is to the lungs and results from inhaling short-lived 222Rn daughter products (Fig. 1) in the atmosphere1. The short-lived daughters (RaA, RaB, RaC and RaC′) decay in the lung to 22-year 210Pb, of which a fraction is absorbed into the blood stream and stored in the skeleton. Correlation coefficients of 0.84 and 0.77 between exposure to the short-lived daughter products and the 210Pb skeletal burden have been reported2,3, but these studies indicate that the concentration of 210Pb in bone may be as much as four times that expected from the inhalation of the short-lived radon daughter atoms alone3. Less than 10 per cent of additional skeletal 210Pb can be expected from inhaled 222Rn stored in body fat. In order that the concentration of 210Pb in bone should be a valid index of exposure to the 222Rn daughter products, it must be shown that 210Pb atoms supplied by other sources are proportional to the 222Rn daughter concentration.