Fukushima macaques show possible effects of radiation, study suggests


Monkeys near the Fukushima No. 1 nuclear plant have lower blood cell counts than cousins living farther away, possibly because of radiation exposure, according to a study released Thursday.

A team of Japanese researchers, including Shinichi Hayama of Nippon Veterinary and Life Science University in Tokyo, wrote in the journal Nature Scientific Reports that although they could not prove the link, the blood levels “might likely be the result of exposure to some form of radioactive material.”

Fewer blood cells could make the monkeys more prone to disease, they said, and “may suggest that the immune system has been compromised to some extent.”

The team compared white and red blood cell levels in macaques living in a forest area in the city of Fukushima, 70 km from the nuclear plant, with that of 31 monkeys living 400 km away on the Shimokita Peninsula.

“Compared with Shimokita monkeys, Fukushima monkeys had significantly low white and red blood cell counts,” the researchers said.

The study sought to examine the health effects of long-term radioactive exposure on wild Japanese macaques following the massive earthquake and nuclear meltdowns at Fukushima No. 1 in March 2011.

In areas with soil contamination levels of 10,000 to 100,000 becquerels of cesium in Fukushima Prefecture, for example, the average white blood cell count in young monkeys was 6,530 per microliter, and the average red blood cell count was 4.326 million per microliter.

That compares with an average white blood cell count of 14,860 per microliter and average red blood cell count of 549.2 million per microliter among young monkeys inhabiting the Shimokita Peninsula in Aomori Prefecture.

Such data from nonhuman primates, our closest relatives, could contribute to knowledge about the health effects of radiation exposure on humans, the team said.

But some commentators criticized the research method.

Jim Smith, an environmental science professor at the University of Portsmouth in Britain, said the dosage inferred in the study was unlikely to have had a significant effect on the monkeys’ blood cell count.

“I think it much more likely that the apparently low blood cell counts in the Fukushima monkeys are caused by something other than radiation,” he said.

Geraldine Thomas, a professor of molecular pathology at Imperial College London, added that the radiation doses would have been less than a person would receive on a flight from London to Tokyo.

The blood cell count may be caused by other factors, such as a new diet or other environmental changes brought on by the tsunami, she said.