Fukushima animal archive. Its establishment and what will be next

The Fukushima Daiichi Nuclear Power Plant (FNPP) accident released large amounts of radioactive substances into the environment. We have established an archive system consisting of organ specimens from over 300 cattle, 50 pigs and 200 Japanese monkeys within and adjacent to the 20-km radius previously set as the evacuation zone of FNPP. We have been determining organ concentration of radionuclides and their biological effect. In all the specimens examined, gamma-rays form radioactive cesium were detectable. Linear correlation was found between radioactivity concentration of ¹³⁷Cs in whole peripheral blood (PB) and that in each organ. The slope of the regression line was organ dependent and was the highest in the skeletal muscles. Radionuclides with the relatively short half-life, ^110mAg was specifically detected in the liver and ^129mTe in the kidney. We think that contribution of external dose to total exposure was higher than previously considered. Cattle were somehow under a slight stress condition without remarkable changes. This study using the archive system is the first to reveal organ distribution of radionuclides attributed to the FNPP accident. However, it is too early to draw conclusion on the effect of the accident. (author)