CRMS releases the analysis report of the entire measurement results
The following is the press release by CRMS which covers the whole research they undertook since July 2011 based on the radioactive monitoring of 6886 food samples. A brief analysis of the research can be found on the bottom of this article. However, the detailed results are only available in Japanese, which is on this page.
What are the actual measurements of radioactive substances in Japanese foods after one year from the revision of government safety criteria?
Citizens' Radioactivity Measuring Station (CRMS; Executive Director: Aya Marumori) has rounded up measurement results of radioactive contamination taken mainly in Fukushima Prefecture after the accident at Tokyo Electric Power Company's (TEPCO) Fukushima Daiichi nuclear power plant.
After 12 March 2011, people living in Japan have been left with no choice but to find ways to live with radiation contamination. Even under the international consensus regarding radiation exposure, there is no threshold that guarantees safety. Each individual must now be aware and do whatever possible to avoid and reduce exposure. Even at this point, we can confirm that radiation has spread not only within the area surrounding the nuclear plant, but it has also spread across prefecture, city and town borders, making it difficult for the various administrations in these areas to handle the matter adequately on their own.
Considering such situation, CRMS has operated as an independent organization that provides individuals with tools that help them measure radiation on their own and learn about radiation protection in order to protect themselves.
In our latest data analyses by March 10th of 2013, 1.25% of the entire items measured exceeded the threshold of 500Bq/kg, which was the government's provisional criterion set right after the accident. When the threshold level was revised to 100Bq/kg in April 2012, the percentage of those that exceeded the new criteria rose to 6.56%. In the same manner, the percentage rose to 12.72% at 50Bq/kg; 35.25% at 10Bq/kg; 42.51% at 5Bq/kg. Radioactive Cesium was detected in 49.6% from 6889 samples.
For more details, please refer to the summary of results in the following page. We have also attached a separate sheet showing details of the measurement analyses. (Only available in Japanese).
Now that we are able to offer our latest measurement results, we hope that members of the press will make further efforts to report about the effects of the nuclear accident, considering the fact that in the past two years the general public have become less interested in the issue.
Summary of the findings
Since July 2011, CRMS has been measuring radioactive contamination caused by the nuclear accident at TEPCO's Fukushima Daiichi nuclear power plant in Fukushima Prefecture. A total of 6,886 items were measured using five different types of measuring devices at eight measuring stations within a period of 18 months. 90% (6,126) of the samples were those either grown or manufactured in Fukushima Prefecture, followed by those from Miyagi Prefecture accounting for 136 samples.
The average radiation measurement for these samples was 28.67Bq/kg for Cesium 137, 20.98Bq/kg for Cesium 134, and 48.54Bq/kg for all radioactive substances combined (Results obtained by using LB200, a simplified measuring device that ignores different types of radionuclide, and a scale formed by combining the results for Iodine 131, Cesium 134 and 137.) The production area that showed the highest level of contamination at 16,740.0Bq/kg was located within Fukushima Prefecture. The prefecture that showed the highest average level, however, was Nagano* at 154.67 Bq/kg, followed by Miyagi at 93.87Bq/kg, and Fukushima at 51.26Bq/kg.
When we applied the threshold of 500Bq/kg, which was the government's provisional criterion immediately after the accident, 1.25% of the entire items exceeded this criteria. However, when we set the threshold to the revised level of 100Bq/kg, 6.56% were found to exceed the level. In the same manner, the percentage rose to 12.72% at 50Bq/kg; 35.25% at 10Bq/kg; 42.51% at 5Bq/kg. The radioactive Cesium was detected in 49.96% from 6,889 samples.
Looking at the level of contamination according to each food item or category, "Specific Item: Dried Shiitake Mushroom" showed the highest contamination level of 16,740.00Bq/kg for all radionucleotides combined. The second highest level of radiation contamination was "Food Category: Mushroom" at 15,704.19Bq/kg, followed by "Food Category: Wild Vegetables" at 6,169.9Bq/kg. Mushrooms, Bamboo Shoots, and Wild Vegetables generally tended to show high levels of contamination, some of which exceeded 500Bq/kg.
The study included 71 environmental samples that were analyzed. "Fukushima city public school's swimming pool" showed the highest level of contamination at 38,100Bq/kg for Cesium 137 and 27,800Bq/kg for Cesium 134. The second highest was detected in "Fallen Leaves from Kawaba-mura of Gunma Prefecture" at 5,450Bq/kg for Cesium 137 and 3,546Bq/kg for Cesium 134, followed by "Fire Woods (cut down before the nuclear accident; surface rinsed with water) at Asaka-machi, Koriyama City" that shows 3,230Bq/kg of Cesium 137 and 3,140Bq/kg of Cesium 134.
Although the Ministry of Health, Labour and Welfare has adopted a food safety criteria of 100Bq/kg in order to regulate foods that are shipped out to consumer markets, it has permitted rounding up the third digit to meet the criteria, which means figures of up to 104.9Bq/kg are considered to be permitted. Taking this into account, it was discovered that there were 22 items whose levels were between 100Bq/kg to 104.9Bq/kg among 6,889 items measured by CRMS.
*Average level for Nagano Prefecture came out high because the total number of items measured was merely 20. In addition, Shogenji mushroom (Cortinarius caperatus), harvested in Karuizawa-machi of Kitasaku-gun, Nagano Prefecture (250km away from Fukushima Daiichi Nuclear Plant), which was sent to CRMS for crosschecking from another citizens’ measuring station in Fuchu City of Tokyo, showed an extremely high level of 3000Bq/kg and was included in the calculation. (For details about the Shogenji mushroom in question, please contact Takagi Jinzaburo Kinen Chofu Shimin Hoshano Sokuteishitsu (Chofu Citizens’ Measuring Center in commemoration of Jinzaburo Takagi)