A comprehensive dose evaluation project concerning animals affected by the Fukushima Daiichi Nuclear Power Plant accident: its set-up and progress

Abstract

It is not an exaggeration to say that, without nuclear accidents or the analysis of radiation therapy, there is no way in which we are able to quantify radiation effects on humans. Therefore, the livestock abandoned in the ex-evacuation zone and euthanized due to the Fukushima Daiichi Nuclear Power Plant (FNPP) accident are extremely valuable for analyzing the environmental pollution, its biodistribution, the metabolism of radionuclides, dose evaluation and the influence of internal exposure. We, therefore, sought to establish an archive system and to open it to researchers for increasing our understanding of radiation biology and improving protection against radiation. The sample bank of animals affected by the FNPP accident consists of frozen tissue samples, formalin-fixed paraffin-embedded specimens, dose of radionuclides deposited, etc., with individual sampling data.

Keywords: Fukushima Daiichi Nuclear Power Plant; animals; archives; radiation effects; sample bank.

Fig. 1.

Comprehensive dose evaluation of animals within and around the ex-evacuation zone of the FNPP accident. This project cannot be accomplished without the development of science, the understanding of people, the opening of information, and adequate funding. A strong research group entitled the ‘Group for Comprehensive Dose Evaluation in Animals from the Area Affected by the FNPP Accident’ (composed of five faculties of Tohoku University, six other universities, two national institutes and a company specialized in chromosome analysis) has been established.

Fig. 2.

Sampling activity. A rent-a-car of van has been maintained since the beginning of this project and equipped with devices for dissection and sampling, including a portable freezer, a centrifuge, electric saws and a power generator (A). Sampling of cattle was started at Kawauchi village (where informed consent from farmers was first obtained) and ended at Okuma town. The roads in the mountainous area were disrupted by the earthquake, so the route taken was dependent on the sampling location (B). The unleashed cattle were trapped by food and water. After each animal was identified from its ear tag, it was anesthetized deeply and euthanized, using a muscle relaxant. Peripheral blood was taken from the jugular vein (C). While the veterinarians were performing the euthanasia, we collected grass with bate, and soil (D). The animal carcasses were brought to a ditch dug on public land (E), where we performed dissection (F). At this location, the organs were separated into four groups; one group destined for radioactivity measurement, two for cryopreservation in the various laboratories, and one for paraffin-embedded blocks (G). Cesium is believed to share transport pathways with potassium (such as the energy-dependent pump and channel). We therefore separated the blood cells from the plasma to avoid diffusion from one to the other during the time between sampling and radioactivity measurement (H).

Fig. 3.

Handling and analysis of materials. Materials were divided up according to their intended analytical purpose.

Fig. 4.

Sample control. All samples were itemized and issued with individual barcodes.

Fig. 5.

Connecting each sample and datum. A simple database was created using Excel (A). An information searching system was set up in conjunction with barcodes (B). Frozen tissue samples from each animal were stored in a single large freezer bag, which was labeled with the laminated barcode issued for that animal; tissue samples from the various organs were individually stored in small bags within the large bag (C).

Fig. 6.

The cumulative number of samples. The project commenced on 29 August 2011 and is continuing. In total, we obtained samples from 302 cattle and 57 pigs (finished on 31 March 2013) and 200 Japanese macaques.