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.