TOKYO -- Researchers found fewer cells that become blood in the bone marrow of wild Japanese macaques living in northeastern Japan's Fukushima Prefecture along with the delayed growth of fetuses after the 2011 nuclear crisis, possibly due to radiation exposure.
Findings of abnormalities in these monkeys have been continuously reported in British scientific journals. Researchers assume that the monkeys ingested items like tree bark contaminated with radioactive cesium emanating from the Fukushima Daiichi Nuclear Power Station.
Tohoku University's Department of Pathology professor emeritus Manabu Fukumoto and his research team performed hematological analysis of adult monkeys captured after the nuclear disaster. They inspected blood cell counts in the bone marrow of 18 monkeys caught in locations within 40 kilometers from the plant, including the city of Minamisoma and the town of Namie. Fukumoto's team then compared the data to that of monkeys from other areas. The results revealed various substances destined to mature into blood, like cells that develop into platelets, had decreased in Fukushima monkeys.
Furthermore, the team observed some blood components had greatly decreased in monkeys with higher internal radiation exposure per day. They estimated the radiation dose from the concentration of radioactive cesium in the monkeys' muscles. Fukumoto explained, "We need to conduct long-term research to see if it (the abnormalities) has an effect on the monkeys' health."
Meanwhile, wildlife zoology expert and Nippon Veterinary and Life Science University professor Shinichi Hayama and his research team examined fetuses in pregnant female monkeys. These monkeys were among those annually captured from 2008 to 2016 by the Fukushima Municipal Government to control their population size. Hayama's research team compared data on 62 fetuses around the time of the meltdowns. They learned that the fetuses had smaller heads and delayed development over their entire bodies after the nuclear incident, in comparison to those before the disaster.
However, the team could not find any change in the nutritional status of the mother monkeys. They concluded that the mother monkeys' radiation exposure may have had an effect on the fetuses.
Hayama assumed that Fukushima monkeys "must have been exposed to high doses of radiation on a whole different scale compared to humans." This is because the monkeys "had consumed food contaminated with radiation, in addition to living near the ground where there were high radiation doses."
Japanese macaques are not included in the wild animals and plants under investigation by the Ministry of the Environment to see the effects of radiation from the nuclear disaster. Five academic associations including the Primate Society of Japan (PSJ) have submitted a request asking that Japanese macaques be included in the research, along with other demands, to the environment ministry.
"Japanese macaques have a long life span of 20 to 30 years and are sedentary," said PSJ Chairman Masayuki Nakamichi. He claimed that "it's absolutely crucial, even for the world, to conduct research on the long-term effects of radiation exposure on Japanese macaques."
(Japanese original by Momoko Suda, Science & Environment News Department)