A study by Japanese scientists evaluating the biological impact of the 2011 Fukushima Daiichi nuclear disaster has uncovered growth differences in wild Japanese monkeys since the disaster.
Shin-ichi Hayama and colleagues at the Nippon Veterinary and Life Science University in Tokyo performed external measurements on fetuses collected from 2008 to 2016. They found that compared with the 31 fetuses conceived before March 11, 2011 -- the date if the disaster -- the 31 conceived after that date had "significantly lower" body weight growth rate and head size.
Hayama has been studying the monkeys since 2008, in particular the bodies of those wild monkeys that are part of annual culling, (or "systematic management," as Hayama calls it) by the Fukushima City government in order to curb the population of monkeys, which are well known for destroying agricultural crops. It was through these studies that Hayama became aware of the changes induced by the exposure to radiation that contaminated large swathes of land in Fukushima and caused the evacuation of around 160,00 residents.
The Fukushima disaster exposed a large number of humans and wild animals to radioactive substances, Hayama states in the paper, which is published in the peer-reviewed Scientific Reports, a Nature publication. While several studies of wild animals in Fukushima looked at the health effects of the disaster, such as abnormalities found in pale grass blue butterfly, carp and wild mice, "there is no research investigating long-term exposure to radiation on mammals that typically have long life-span to date," according to the study. "This study is the first report to observe long-term biological effects of the pre- and post-NPP disaster on non-human primates in Fukushima," it continues.
According to an article in Forbes, Hayama recently presented his research as part of the University of Chicago where he said: "I’m not a radiation specialist, but because I’ve been gathering data since 2008 ... it seems obvious to me that this is very important research. I’ve asked radiation specialists to take on this research, but they have never been willing to take this on because they say we don’t have any resources or time to spare because humans are much more important ... If we don’t keep records, there will be no evidence and it will be as if nothing happened.”
Hayama's team had previously studied radioactive exposure and its effect on the health of Japanese monkeys in Fukushima City. The prefecture capital is located approximately 70 km from the Fukushima No. 1 Nuclear Power Plant that experienced multiple meltdowns and explosions in March 2011, but had nonetheless shown high concentrations of radiocesium in its soil. The team looked into chronological changes in muscle radiocesium concentrations in monkeys inhabiting the city from April 2011 to June 2012. The cesium concentration in monkeys’ muscle captured at locations with high radioactive concentrations actually decreased over the 3 months following the disasters, only to increase again in some animals during and after December 2011, although it returned to previous levels the following April.
The results suggested that "the short-term exposure to some form of radioactive material resulted in hematological changes in Fukushima monkeys," according to that study.
"The effects associated with long-term low-dose radiation exposure on fetuses are among the many health concerns," Hayama states. "Children born to atomic bomb survivors from Hiroshima and Nagasaki showed low birth weight, high rates of microcephaly, and reduced intelligence due to abnormal brain development. Experiments with pregnant mice or rats and radiation exposure had been reported to cause low birth weight, microcephaly or both."
Hayama's team also identified a similar study on wild animals following the Chernobyl nuclear accident in 1986. The report found that "the brains of birds captured in the vicinity of the Chernobyl NPP weighted lower compared to those of birds captured elsewhere."
The full report can be found here