Radioactive cesium and potassium in cattle living in the 'zone in preparation for the lifting of the evacuation order' of the Fukushima nuclear accident.

To contribute to the reconstruction of livestock industry in Fukushima, radioactive cesium (134 Cs, 137 Cs) and potassium (4 °K) were measured in various tissues of beef cattle living in an area where the evacuation order will be lifted in the near future. Radioactive cesium concentration was less than 100 Bq/kg in most of the samples. Skeletal muscles and kidney had the highest concentrations of radioactive cesium, whereas the liver was lowest among samples, excepting blood. Radioactive cesium concentration in the sirloin, tenderloin and top round was significantly higher than that in the neck muscle. Radioactive cesium concentration in the urine was not correlated with that in the blood, but the relationship became proportional when corrected with urinary 4 °K. Distribution of 4 °K was similar but not identical to that of radioactive cesium. These results suggest that it will be possible to resume livestock production in this area after the decontamination measures are completed and the evacuation order is lifted. Contamination level of living cattle can be estimated not only by blood samples but also by urine samples. If 50-100 Bq/kg of cesium is detected in the neck muscle at a slaughterhouse, the cattle should be reinspected using a sample from different muscles.

A case study of the estimation of occupational internal dose using urinary excretion data obtained in a biomedical research facility.

This paper presents a fundamental investigation of the screening of intakes and the estimation of internal doses for workers at a biomedical research facility from their urinary excretion data. Urine samples from the workers were collected immediately before and several days after handling radioactive materials, and 5-mL portions were measured directly with a sodium iodide scintillation detector or a liquid scintillation detector. Intakes of radionuclides and effective doses were estimated from the data using the Internal Dose Easy Calculation code. Blank levels of radioactivity and detection limits for this method were determined from the radioactivity contained in urine samples collected from volunteers working outside the controlled area (control samples). Most of the radioactivity in the control samples was attributed to K. Under the present experimental conditions, the detection limits for the committed effective doses were 7.5 x 10(-4) mSv for 125I and 6.9 x 10(-2) mSv for 35S in the case of samples collected 1 d after handling. Accordingly, it can be determined whether workers were exposed more than the recording level (1 mSv of committed effective dose) or not. No workers in the surveyed facility were found to suffer internal exposure beyond the recording levels, and their intakes were estimated to be below the detection limits in the 2-y investigation period. In an ordinary facility of biomedical research, the amount of unsealed radioactivity handled at one time is within 10 MBq in many cases, and the air ventilation and filtering systems work adequately. Under such circumstances, the present results suggest that individual monitoring, such as urine analysis, is omissible in many cases as a routine monitoring of internal exposure for workers.

Cytogenetic damage in lymphocytes of healthy and thyroid tumor-affected children from the Gomel region (Belarus).

During 1994, 19 thyroid tumor-affected children and 17 healthy children from the Gomel region, one of the areas most polluted by the Chernobyl fallout, were analysed for (i) the presence of in their urine and (ii) chromosome aberrations (CA) in circulating lymphocytes. They were compared with 35 healthy children from Pisa, Italy. Tumor-affected children showed significantly (p<0.05) higher levels in their urine as compared to healthy controls from the Gomel region. No radioactivity was found in urine from the Pisa controls. CA frequency was significantly higher in tumor-affected children compared to the Gomel controls, but was not significantly different between Gomel and Pisa controls. However, dicentric chromosomes were found in a significantly (p<0.01) greater proportion in both affected and healthy Gomel children (3.4 and 1.3/1000 cells, respectively) as compared to the Pisa controls (0.4/1000 cells). Multiple regression analysis showed that the proportion of cells with acentric fragments, dicentric and ring chromosomes was significantly correlated (p<0.05) with the amount of excreted in their urine. These findings suggest that children from the Gomel region were still being exposed to radionuclides, which makes it possible to study a dose-effect relationship.

Whole body content and turnover of Cs and K.

In persons who had accumulated radiocesium from the fallout of the Chernobyl nuclear reactor accident, the amount of radiocesium and radiopotassium was measured in the total body and in urine. The stable Cs content in the urine was determined at the same time by instrumental nuclear activation analysis. From the data obtained, the total body Cs pool was calculated to be 1500 micrograms, that of K 110 g. The Cs turnover rate was found to be 0.64%/d for men and 0.81 for women; the K turnover 2.4 and 2.7, respectively. The Cs:K ratio in the total body was 4 times higher than that in urine, demonstrating that, in relation to the intake, the body is able to accumulate more Cs than K.