12 Mars 2013
March 9, 2013
The Asahi Shimbun
Radiation testing shows a sharp decline in internal exposure levels among Fukushima Prefecture residents, two years after the Fukushima No. 1 nuclear power plant accident.
Of the 106,000 people the prefecture tested using whole body counter (WBC) devices, which can measure the presence of radioactive materials, by the end of December, 99.98 percent measured less than 1 millisievert.
Of about 34,000 people who were tested at Hirata Chuo Hospital in Hirata village from Oct. 17, 2011, to the end of 2012, most showed levels of radioactive cesium-137 below the detectable limit.
Less than 1 percent of people who were tested in May 2012 or later showed signs of radiation exposure.
Minami-Soma municipal general hospital has been testing residents’ internal exposure using two WBCs. The results of testing between April and September last year already showed a monthly decline in the ratio of residents in whom cesium levels were detectable.
“As a whole, levels of internal exposure are low," said Masaharu Tsubokura, a physician who has been working on the testing program at the Minami-Soma municipal hospital. "The situation now is not one that consuming food from Fukushima Prefecture can raise one’s internal radiation level. Still, I hope (people from the Fukushima plant affected area) will continue to be tested.”
WBCs have also been independently installed in Fukushima city, Date, Soma and Namie.
Asked about eating habits, some with relatively high levels of internal radiation exposure said they had consumed homegrown "shiitake" mushrooms grown on wood chips. When tested, some shiitake mushrooms showed high levels of more than 10,000 becquerels per kilogram.
Doctors advised the people eating contaminated mushrooms to switch to commercially distributed food, such as foodstuffs sold in supermarkets. Their radiation levels dropped when the second and third tests were conducted within three months.
Inhaling radioactive particles released into the air immediately after the nuclear plant accident and their accumulation in the food chain contribute to increased internal exposure radiation levels.
In checkups conducted in 2011, many of those tested showed higher levels of exposure due to inhaling radioactive particles, but cesium levels dropped because the substances were excreted through urine.