A method for estimating radioactive cesium concentrations in cattle blood using urine samples

Abstract

In the region contaminated by the Fukushima nuclear accident, radioactive contamination of live cattle should be checked before slaughter. In this study, we establish a precise method for estimating radioactive cesium concentrations in cattle blood using urine samples. Blood and urine samples were collected from a total of 71 cattle on two farms in the 'difficult-to-return zone'. Urine Cs, specific gravity, electrical conductivity, pH, sodium, potassium, calcium, and creatinine were measured and various estimation methods for blood Cs were tested. The average error rate of the estimation was 54.2% without correction. Correcting for urine creatinine, specific gravity, electrical conductivity, or potassium improved the precision of the estimation. Correcting for specific gravity using the following formula gave the most precise estimate (average error rate = 16.9%): [blood Cs] = [urinary Cs]/([specific gravity] - 1)/329. Urine samples are faster to measure than blood samples because urine can be obtained in larger quantities and has a higher Cs concentration than blood. These advantages of urine and the estimation precision demonstrated in our study, indicate that estimation of blood Cs using urine samples is a practical means of monitoring radioactive contamination in live cattle.

Comparison of urine and blood as a convenient and practical sample for estimating the contamination level of live cattle with radioactive cesium

“…The concentration of 137 Cs in urine and blood samples ranged from 508 to 2,619 Bq/kg and from 76 to 319 Bq/kg respectively (Figure ). On an average, the concentration in urine was 9.9 times higher than that in blood, although the concentration ratio was 5.7 in our previous study (Sato, Yamagishi, et al, ). The concentration of 137 Cs in blood was estimated accurately from urine (Table ), in spite of the large difference of the urine/blood ratio of 137 Cs.…”

“…The concentration of 137 Cs in blood was estimated by the following equation (Sato, Yamagishi, et al, ). The accuracy of this estimation was evaluated by the same way as above.…”

“…However, the apparatus for this measurement is large, and cannot be transported easily. Therefore, we developed a new method to estimate the concentration of radioactive cesium in blood using urine samples (Sato, Yamagishi, et al, 2017). However, the concentration of radioactive cesium in blood is considerably lower than that in muscles, taking long time to measure blood samples accurately.…”

“…In contrast, urine samples can easily be collected by farmers themselves, and they are expected to have higher concentrations of radioactive cesium than blood samples. Therefore, we developed a new method to estimate the concentration of radioactive cesium in blood using urine samples (Sato, Yamagishi, et al, ). This method estimated the concentration of radioactive cesium in blood with an average error rate of 16.9%; however, whether urine is a better sample than blood has not been verified.…”

“…Therefore, we developed a new method to estimate the concentration of radioactive cesium in blood using urine samples (Sato, Yamagishi, et al, 2017). This method estimated the concentration of radioactive cesium in blood with an average error rate of 16.9%; however, whether urine is a better sample than blood has not been verified.…”