For the first time since the triple meltdown at the Fukushima No. 1 plant throttled the agriculture-reliant prefecture, all rice produced there last year cleared the required radiation tests.
The Fukushima Prefectural Government last year checked every bag of rice produced in the prefecture — some 10.75 million bags — based on the Food Sanitation Law, which bans the sale of rice radiating more than 100 becquerels of cesium per kilogram.
The tests found all bags checked from January 2014 through December 2014 had lower than standard radiation levels, in contrast with those tested in 2012 and 2013, which had a small percentage of rice unfit for shipment, the prefectural government said.
Officials said they hope the results will help raise consumer confidence in Fukushima rice, which was devastated by the nuclear disaster. Experts attribute the achievement to efforts to prevent cesium from entering rice fields during cultivation, and to the use of fertilizers based on potassium chloride, which prevents the grain from absorbing the isotope.
The tests, introduced in 2012, screen the bags on a conveyer belt. Bags sniffed out by the initial screening are tested further with precision instruments. Bags over the 100-becquerel cesium limit are discarded.
In 2012, a total of 10.35 million bags were tested and 71, or 0.0007 percent, failed.
In 2013, the failure rate was reduced to just 28 bags, or 0.0003 percent of the 11 million bags tested.
In 2014, 29 bags were flagged as suspicious by initial screening but later found to be below the cesium threshold.
Given that 867 bags were weeded out by initial scans in 2012, the 2014 results represent a major advance, they said.
To date, the rice farmers, prefectural government and local JA cooperatives have made joint efforts to promote fertilizers based on potassium chloride, which prevents rice from absorbing cesium.
The prefecture is shouldering all costs for the fertilizers. In 2014, it distributed ¥1.61 billion in subsidies to farmers to buy enough potassium chloride-based fertilizer to treat 68,000 hectares of paddies.
Research has shown putting potassium in soil prevents rice from taking in cesium. But it is important to keep the potassium levels high while rice is young. So farmers have been told to keep adding it.
Keisuke Nemoto, a professor at the University of Tokyo’s Laboratory of Crop Ecology and Morphology who is studying how cesium gets into rice, said the 2014 test results represent the fruit of the joint effort.
But Nemoto said his experiments showed that rice grown without potassium-based fertilizers still breaks the 100-becquerel cesium limit.
“Unless farmers keep adding potassium to soil every year, the chemical’s density in soil will decline and rice could start absorbing cesium again,” he warned.
This section, appearing every third Monday, focuses on topics and issues covered by the Fukushima Minpo, the largest newspaper in Fukushima Prefecture. The original article was published Jan. 9.