AbstractThe damage caused by the earthquake on 11 March, 2011 resulted in a serious nuclear accident in Japan. Due to the damage to the Fukushima Daiichi Nuclear Power Plant (FNPP), large amounts of radioactive substances were released into the environment. In particular, one of the largest safety concerns is radioactive cesium (134Cs and 137Cs). Due to the FNPP nuclear accident, a 20 km area was restricted from human activity, and various types of domestic animals were left in the zone. We collected the organs and tissues from sacrificed animals to obtain scientific data to evaluate the internal deposition of radioactive compounds. At first, we found there is a strong correlation between blood 137Cs and organ 137Cs with data from 44 cattle, indicating that skeletal muscle is the target organ of deposition of radioactive cesium. Second, we analyzed the relationship between blood 137Cs and muscle 137Cs within relatively lower radioactive concentration, suggesting that estimation of concentration of 137Cs is possible from blood concentration of 137Cs. Finally, we developed computer software to estimate the muscle 137Cs concentration from blood samples. Our study contributes to the food safety of livestock products.