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Strontium transfer from maternal skeleton to the fetus estimated on the basis of the Techa river data
Measurements of 90Sr in human bone of inhabitants of the Techa river region were started in 1951, and since 1974 the Techa river population has been studied with a whole-body counter. One of the dosimetric tasks that could be decided using data on 90Sr measurements is direct evaluation of strontium transfer to the fetus from the maternal skeleton. Six cases were selected for which 90Sr measurements were available both for stillborn infants and their mothers. The ratio of 90Sr concentrations in fetal bone to maternal bone for the year of pregnancy has been evaluated. Two clusters of values were found and the difference between clusters could be explained by age-dependent features of maternal bone formation and remodelling. When the mother's 90Sr intake occurred in the period of intensive compact bone growth, the transfer coefficient was very low (0.012-0.032). If 90Sr ingestion occurred during the woman's reproductive age, the transfer to fetus was equal to 0.21-0.26.
Retrospective dosimetry related to chronic environmental exposure
Radioactive contamination of the environment occurred in the early fifties as a result of the releases from the Mayak plutonium production complex (Southern Urals, Russia). The releases of liquid wastes into the Techa river resulted in chronic exposure of 30,000 residents of the riverside communities. Since 1951 90Sr body burdens have been measured for over half of this cohort. This paper presents the analysis of data on 90Sr in humans and describes the reconstruction of internal doses for these people.
Evaluation of portable air samplers for monitoring airborne culturable bacteria
Airborne culturable bacteria were monitored at five locations (three in an office/laboratory building and two in a private residence) in a series of experiments designed to compare the efficiency of four air samplers: the Andersen two-stage, Burkard portable, RCS Plus, and SAS Super 90 samplers. A total of 280 samples was collected. The four samplers were operated simultaneously, each sampling 100 L of air with collection on trypticase soy agar. The data were corrected by applying positive hole conversion factors for the Burkard portable, Andersen two-stage, and SAS Super 90 air samplers, and were expressed as log10 values prior to statistical analysis by analysis of variance. The Burkard portable air sampler retrieved the highest number of airborne culturable bacteria at four of the five sampling sites, followed by the SAS Super 90 and the Andersen two-stage impactor. The number of bacteria retrieved by the RCS Plus was significantly less than those retrieved by the other samplers. Among the predominant bacterial genera retrieved by all samplers were Staphylococcus, Bacillus, Corynebacterium, Micrococcus, and Streptococcus.