Wild Japanese monkeys near the Fukushima Daiichi nuclear power plant have lower blood cell counts than similar monkeys who lived almost 200 miles away, according to biologists.
According to researchers, monkeys in the vicinity of Fukushima City had detectable levels of radioactive cesium in their muscles, while the northern monkeys did not. Researchers also found that the Fukushima simians had significantly lower white and red blood cell counts compared with macaque troops almost 200 miles away.
"These results suggest that the exposure to some form of radioactive material contributed to hematological changes in Fukushima monkeys," argued the study's lead author, Kazuhiko Ochiai, a researcher at Nippon Veterinary and Life Science University in Tokyo, and colleagues.
The monkeys -- 61 from Fukushima and 31 from Shimokita -- were collected over a one-year period beginning in April 2012. The Fukushima nuclear plant released a large amount of radioactive material into the environment following a massive Japanese earthquake on March 11, 2011.
Study authors said the consequences of their findings remained unclear.
"Low blood cell cont does not necessarily mean that the health of individual monkeys is at risk," the authors wrote. "However, it may suggest that the immune system has been compromised to some extent, potentially making individual animals and the entire troop susceptible to, for example, epidemic infectious disease."
The researchers suggested their findings mirrored studies conducted on human health impacts following the Chernobyl disaster, where researchers found decreased blood cell counts in people living in contaminated areas.
"Data from non-human primates -- the closest taxonomic relatives of humans -- should make a notable contribution to future research on the health effects of radiation exposure in humans," the authors wrote.