The Citizens’ Research Group on Internal Radiation Exposure
Our purpose, objectives and mission:
Awareness and Information Sharing
- To share information on internal radiation exposure.
- To conduct seminars and organize speeches and lectures throughout Japan to spread correct information on radiation and internal radiation exposure.
- To conduct study as a citizens’ association to think on internal radiation exposure and nurture trainers and lecturers from among the citizens.
- To support the efforts of guardians to safeguard their wards from internal radiation exposure at nursery schools, kindergartens, primary schools, junior high schools, high schools, colleges and universities by giving them proper advice and suggestions.
- To conduct lectures organized by cities, towns, villages, as well as the educational committees; such as the emergency seminar “Knowing the impact on health by radiation and radioactive substances”.
- To establish the link between consumers and producers in order to secure the safety of food.
- To recommend food below 4 Bq (Becquerel)/kg (below 4cpm) especially for pregnant women, infants on lactation, children and the youth.
- To recommend the producers who voluntarily follow this standard and guide them in selling their products.
- To introduce the food items below 4 Bq/kg and aim at establishing the supply system to supply such products for mid-day meal and the families with pregnant women as well as infants and children.
Safeguarding Land and Water
- To support improvement of agricultural land that is affected by radiation. If it is not possible to improve, then to request the government to offer an alternative site/s.
- To conduct the trend of the tide year-round, do the continuous survey on the seabed, and to check the quality of seawater, since there is a serious problem of marine pollution.
- To define regions where fishing activities need to be prohibited and request the government to compensate the fishermen.
Funding and Compensation
- To establish funds of the association to compensate the loss of the producers whose products are affected by radiation and cannot sell them in the market.
- To give advice on the demand of compensation for the loss from TEPCO.
Daigo Fukuryū Maru-Fishing Boat Incident
On March 1, 1954, The Daigo Fukuryū Maru (Lucky Dragon 5), a Japanese tuna fishing boat, was exposed to and contaminated by nuclear fallout from the United States’ Castle Bravo thermonuclear device test on Bikini Atoll. Nuclear fallouts are called as “the ashes of death”.
At that time, fish was one of the staple diets for Japanese people. Fish was contaminated due to nuclear fallouts. The entire ship itself was contaminated. Not just Daigo Fukuryū Maru, but also minimum 856 ships were covered under “the ashes of death” and the fishermen got the effect of radiation. The Hibakusha of the Bikini incident have not been given even any special health card.
The issue became out of sight, out of mind.
At that time, the government had disposed all the tunas which were affected by radioactive substances at the level of more than 100 cpm (cpm means count per minuite). They thought that the gills of tunas would be affected most by radiation. Therefore, all tunas with more than 100 cpm were disposed by reclaiming land from the sea.
The tool to measure radiation in food and water is called “Ge (germanium) Semiconductor Detector”.
On the other hand, the tool to measure air radiation dose is called “Geiger-Müller Counter”.
Comparison between count per minute (cpm) and Bequelel (Bq)
Count per minute (cpm) is the unit measured with GM survey meter of the area within 10cm2 and 1 cm above the surface.
Bequelel (Bq) means the amount of radiation released per second out of the food item weighing 1kg.
Beef with 500 Bq/kg means the meat radiates 500 times more than normal meat per second.
If you try to convert it with the unit of cpm, it is not so simple to do so. In fact, we cannot convert the unit of cpm into Bq/kg.
This is because of the fact that cpm measures the amount of radiation per minute on a certain area and that Bq/kg defines the amount of radiation per second of a certain weight.
Calculation of Radioactive Contamination of Water and Food
So far, radioactive contamination of water and food has been tested with Germanium Semicondoctor Detector. With this method, it would take for about 6 hours to the precision upto 0.1 Bq/kg. Further, to reach the precision upto 0.2 Bq/kg, it would take one hour. In addition, to conduct such tests, meat or vegetables need to be finely chopped or a blender should be used and the test item must be put in a Marinelli Beaker. This makes it impossible to check each and every food item.
It has been said that the affected tunas called “Ganbaku Maguro”, with their gills counted the score of 100 cpm, would count around 50-100 Bq/kg when they were tested with the tool of GM Survey Meter.
Based on this finding, it was decided that whichever tuna meat was with the count of more than 100 Bq/cpm on the gills of the tunas would be disposed off.
In the year 1954, fish in Japan used to carry 50-100 Bq/kg.
After the disaster at Fukushima Daiichi Nuclear Power Plant, the provisional regulation count was revised by the Government of Japan on 17 March 2011. It was relaxed and raised to the level of 500 Bq/kg for both adults and children, which is five to ten times more compared to the level of 1954.
How can we protect the health of our children?
We will aim at realizing the measurement of the effect of radiation on food by using GM Survey Meter by considering the example of this “Genbaku Maguro.”
The actual count of the gills of “Genbaku Maguro”carried 100 cpm, its meat counted 50-100 Bq/kg.
We should proceed with the advice provide by German Society for Radiation Protection (Gesellschaft für Strahlenschutz e.V.):
The basis for estimates of health effects being uncertain, we must recommend that no food with a concentration of more than 4 Becquerel of the leading radionuclide Cesium-137 per kilogram shall be given to infants, children and adolescents. Grown-ups are recommended to eat no food over 8 Becquerel per kilogram of the leading nuclide Cesium-137.
The standard level below 4 Bq/kg is based on “The Advice on Minimising the Radiation Risk in Japan (Empfehlungen zur Minimierung des Strahlenrisikos in Japan)” presented by German Society for Radiation Protection on 20 March 2011 (http://www.strahlentelex.de/Stx_11_582_S12-14.pdf).
Food and Liquid Safe for Consumption
We aim not to let the children take food and drink with more than the count of 4 cpm, and 8 cpm for the adults which would be properly measured with GM Survey Meter.
We need to do research on the relationship between the levels of cpm and Bq/kg of actual food item.
It would take for about 5 minutes to measure the level of cpm of any food item with GM Survey Meter.
With the co-operation of research institutions, we would like to publicise the results of testing onto the level of radiation among the food items, such as rice, vegetables, meat, fish, and so on.
The Citizens’ Research Group on Internal Radiation Exposure,
Shinya Kawane ,representative