[en] The naturally occurring concentrations of radium (²²⁶Ra and ²²⁸Ra) in public and private water supplies have been studied for many years. Both general surveys ad local studies have established the geographical regions where well waters exceed 3 pCi/L (1-17). In general, the ²²⁶Ra was determined by the emanation method, while the ²²⁸Ra was determined from the beta activity of the ²²⁸Ac daughter. In a recent review (18) of the methods used ''a number of approved analytic methods can bear improvement, especially the method for 228Ra.'' The purpose of the work described here was to develop an improved method for the simultaneous determination of ²²⁶Ra and ²²⁸Ra. 22 refs., 3 tabs

[en] The naturally occurring concentration of ₂₂₆Ra in public and private water supplies has been a subject of study for many years. Both general surveys and local studies have been made. The geographical areas in the United States where water has a ₂₂₆Ra concentration exceeding 3 pCi/L are relatively well established, at least for public supplies. These studies have shown that wells obtaining water from the deep sandstone aquifers in the Midwest frequently have ₂₂₆Ra concentrations ranging from 5 to 25 pCi/L. The present study summarizes results obtained on more than 2000 samples collected between 1950 and 1978. Most of the samples were analyzed at Argonne by the emanation method; the rest were analyzed at the State Hygienic Laboratory in Iowa City, Iowa. The minimum sensitivity for ₂₂₆Ra was about 0.05 pCi/L at Argonne and about 0.4 pCi/L at Iowa City. The minimum sensitivity for ₂₂₈Ra was about 0.5 pCi/L at both laboratories

[en] Continuous monitoring of ²²²Rn concentrations in the air in houses is the most appropriate approach for the real-time measurements, but this requires complex and expensive instruments and is not practical for large studies. Activated carbon canisters have been used extensively for determining the average concentration over a period of a few days. The ''open face'' charcoal detectors have an integration time constant of about 14 h so that they are sensitive to short-term transient changes in the radon concentration. In addition, water uptake at high relative humidities reduces the radon uptake by the charcoal. The addition of a diffusion barrier and a nylon screen results in a charcoal detector with an integration half-time ranging from 20 to 60 h and a reduced uptake of water at high humidities. Silicone rubber sheeting is relatively permeable to radon and impermeable to water vapor. It was the purpose of this study to evaluate the effect of a silicone barrier on the charcoal canister radon collective device. 3 refs

[en] Radon counting chambers which utilize the alpha-scintillation properties of silver activated zinc sulfide are simple to construct, have a high efficiency, and, with proper design, may be relatively insensitive to variations in the pressure or purity of the counter filling. Chambers which were constructed from glass, metal, or plastic in a wide variety of shapes and sizes were evaluated for the accuracy and the precision of the radon counting. The principles affecting the alpha-scintillation radon counting chamber design and an analytic system suitable for a large scale study of the ²²²Rn and ²²⁶Ra content of either air or other environmental samples are described. Particular note is taken of those factors which affect the accuracy and the precision of the method for monitoring radioactivity around uranium mines

[en] Variations in efficiency as large as 3% have been found for radon scintillation counting systems in which the photomultiplier tubes are sensitive to the thermoluminescent photons emitted by the scintillator after exposure to light or for which the resolution has deteriorated. The additional standard deviation caused by counting a radon chamber on multiple counting systems has been evaluated and the effect, if present, did not exceed about 0.1%. The chambers have been calibrated for the measurement of radon in air, and the standard deviation was equal to statistical counting error combined with a systematic error of 1.1%. 3 references, 2 figures, 2 tables

[en] Determinants of time-until-tumor for osteosarcoma in US radium cases have been reevaluated. Classically, a minimum induction period (latency period) of about five years has been recognized, but not an expression period. Lack of long induction periods at igh doses has been ascribed to scarcity of subjects at risk. Recent experiments have suggested that induction periods are directly lengthened as doses decrease. Reanalyses of time-until-tumor data for 57 measured female osteosarcoma cases exposed to ₂₂₆Ra and /or ₂₂₈Ra support new interpretations: time-until-tumor for osteosarcomas is best described by age at tumor appearance, not by induction period; age at diagnosis increases as estimated initial radium intake decreases; and, there exists an expression period which can be truncated at the low end by the minimum induction period (or by age at exposure). The downturn in sarcoma incidence at very high doses is describable as the truncation of the expression period on its early side by the minimum induction period. These results depend strongly on the assumption of homogeneity of time-until-tumor processes in diial workers and in iatrogenic radium exposure cases

[en] Concentrations of ²³²Th and activity ratios of ²²⁸Th to ²³²Th and ²³⁰Th to ²³²Th were determined in autopsy samples from five former employees of a thorium refinery. The ranges of ²³²Th activity concentrations (mBq per gram of wet tissue) were 0.17--94 in lungs, 3.9--1,210 in pulmonary lymph nodes, 0.14--1.19 in bones, 0.015--0.68 in liver, 0.97--5.8 in spleen, and 0.009--0.068 in kidneys. These concentrations are 10 to 1,000 times greater than have been reported for persons not occupationally exposed to thorium. In most of the samples, the ratios of ²²⁸Th to ²³²Th and ²³²Th to ²³²Th activity at death of the subject were 0.2--0.4 and 0.1--0.2, respectively. ²²⁸Th to ²²⁸Ra activity ratios (± standard errors) of 0.86 ± 0.11 in lungs and 1.18 ± 0.13 in lymph nodes of one subject were obtained by calculation from ratios of ²²⁸Th to ²³²Th

[en] Determinants of time-until-tumor for bone sarcomas in US radium cases have been reevaluated. For the 57 measured female bone sarcoma cases exposed to ²²⁶Ra and/or ²²⁸Ra, ages at appearance of tumor are more strongly correlated with radium intake doses than are latency periods

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No abstract available