Small head size and delayed body weight growth in wild Japanese monkey fetuses after the Fukushima Daiichi nuclear disaster

Shin-Ichi Hayama,Takuya Kato,Toshinori Omi,Fumiharu Konno,Setsuko Nakanishi,Naomi Ishii,Aki Tanaka,Moe Tsuchiya,Yoshi Kawamoto,Sachie Nakiri,Kazuhiko Ochiai

doi:10.1038/s41598-017-03866-8

Abstract

To evaluate the biological effect of the Fukushima Daiichi nuclear disaster, relative differences in the growth of wild Japanese monkeys (Macaca fuscata) were measured before and after the disaster of 2011 in Fukushima City, which is approximately 70 km from the nuclear power plant, by performing external measurements on fetuses collected from 2008 to 2016. Comparing the relative growth of 31 fetuses conceived prior to the disaster and 31 fetuses conceived after the disaster in terms of body weight and head size (product of the occipital frontal diameter and biparietal diameter) to crown-rump length ratio revealed that body weight growth rate and proportional head size were significantly lower in fetuses conceived after the disaster. No significant difference was observed in nutritional indicators for the fetuses’ mothers. Accordingly, radiation exposure could be one factor contributed to the observed growth delay in this study.

Highlights

We previously studied radioactive exposure and its effect on health of Japanese monkeys (Macaca fuscata) inhabiting Fukushima City, which is located approximately 70 km from the Fukushima Daiichi NPP5, 6
Radiocesium was detected in mothers’ muscle that had conceived after the NPP disaster (Table 1)
Muscle radiocesium concentrations in wild Japanese monkeys captured in 2012 in Aomori Prefecture, which is located in the Tōhoku region 400 km north from the NPP, were below the detection limit[2], we assumed that the muscle radiocesium concentrations in the Japanese monkeys in Fukushima City prior to the disaster were below the detection limit

Summary

Introduction

We previously studied radioactive exposure and its effect on health of Japanese monkeys (Macaca fuscata) inhabiting Fukushima City, which is located approximately 70 km from the Fukushima Daiichi NPP5, 6. Fukushima monkeys had significantly lower white and red blood cell counts, hemoglobin, and hematocrit, and the white blood cell count in immature monkeys showed a significant negative correlation with muscle cesium concentration[6]. These results suggested that the short-term exposure to some form of radioactive material resulted in hematological changes in Fukushima monkeys. Our research group studied the reproductive and nutritional status of the Japanese monkey population by performing autopsies on individuals captured and euthanized by Fukushima City[17] These Japanese monkeys were the first wild primate population exposed to radiation as result of nuclear disaster. There was no other study either in Chernobyl or Fukushima that followed fetal development over time or compared fetal development before and after long-term radiation exposure in the same wild animal populations

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