Concentrations of 137Cs radiocaesium in the organs and tissues of low-dose-exposed wild Japanese monkeys

Abstract

Objectives: Following the massive earthquake that struck eastern Japan on March 11, 2011, a large amount of radioactive material was released into the environment from the damaged reactor of the Fukushima Daiichi Nuclear Power Plant (FDNPP). After the FDNPP accident, radiocaesium was first detected in muscle samples from wild Japanese monkeys exposed to radioactive materials, and haematologic effects, changes in head size, and delayed body weight gain were also reported, but little is known about the distribution of ¹³⁷Cs in the organs and tissues of wild Japanese monkeys.

Results: We detected the ¹³⁷Cs in various organ and tissue samples of 10 wild Japanese monkeys inhabiting the forested areas of Fukushima City that were captured between July and August 2012. Among muscle, brain, heart, kidney, liver, lung, and spleen, muscle exhibited the highest and the brain the lowest ¹³⁷Cs concentration. The concentration (mean ± SD) of ¹³⁷Cs in muscle, brain, heart, kidney, liver, lung, and spleen was 77 ± 66, 26 ± 22, 41 ± 35, 49 ± 41, 41 ± 38, 53 ± 41, and 53 ± 51 Bq/kg, respectively. These results can help us understand the biological effects of long-term internal radiation exposure in non-human primates.

Keywords: Caesium; Fukushima Daiichi Nuclear disaster; Japanese monkeys; Radioactive contamination.

Fig. 1

Distribution of ¹³⁷Cs in organ and tissue samples collected from 10 Japanese monkeys in 2012. Graph shows the ratio of the concentration of ¹³⁷Cs in each organ to that in muscle (¹³⁷Cs in each organ/¹³⁷Cs in muscle). Error bars indicate SD