Fukushima produces first thesis on effects of internal radiation exposure on children

A thesis which assesses the risks of internal radiation exposure within Fukushima Prefecture following the explosions at the Fukushima Daiichi nuclear power plant, suggests that the effects of internal radiation fall far below that recorded after Chernobyl.

Ryugo Hayano, who works as a professor at Tokyo University’s Science Research Department, has collected the findings of doctors who conducted research into internal radiation exposure among those living inside of the Fukushima Prefecture. He consolidated these findings into an English journal titled "Proceedings of Japan Academy Series B89," which is available on the Internet.

The latest journal is a collection of reports that looks at the degree of radiation exposure through daily food consumption and it is reported to be the first of its kind.

Hayano comments, “Findings suggest that the level of internal radiation exposure brought about by pollution from the soil within the Fukushima Prefecture is much less than originally believed. The amount is so negligible that it is difficult to imagine there being any risk to the health.”

Something that is generally unknown to most living outside of Fukushima is that since the nuclear accident, there have been numerous organizations carrying out their own individual investigations into the effects of radiation. The largest-scale whole body counter (WBC) began in June 2011. Experts in the field used the WBC to examine the effects cesium had on the body of 118, 904 inhabitants inside of Fukushima. Surprisingly, of those who took part, 99.9% fell within the safety standard limit of 1 millisievert (mSv). While such a result is positive, the investigation does not provide elaborate details on the inhabitants’ daily intake of cesium, which arguably also requires close monitoring.

The findings from the most recent thesis by Fukushima Prefecture draw upon tests conducted by Fukushima Hiratamura’s Hirata Central Hospital. The results were obtained by examining 32,811 patients from Fukushima and Ibaraki Prefecture from the periods of October 17, 2011 to November 30, 2012. Of the patients tested, 10,000 were reported to be living in an environment where the soil was contaminated with 100,000 becquerels of cesium 137 per square meter.

The number of participants whose levels of radioactive contamination exceeded the WBC upper limit of 300 becquerels formed just 4.7%. Even more encouraging is that this figure, when looked at per kilogram, fell below the 50 becquerel range. Of the studies that took place after March 2012, this figure fell even further to just 1%. In particular, after May 2012 cesium was undetected in the children whose previous radioactive intake exceeded the upper 300-becquerel limit.

The thesis also addresses the skepticism surrounding the idea that the above figures do not accurately represent the average citizen of Fukushima for the reason that only the most health-conscious person is inclined to volunteer to take part in the tests. It resolves this possible bias by including results carried out from a whole body counter which targeted almost all the students at Miharamachi elementary school located 50 kilometers from the nuclear plant. In 2011, of the 1,494 students who were monitored, 54 students exceeded the upper limit reading.

However, as was the case with the other experiment, from August 2012 the detection of radiation dropped to zero. Around 20% of those living in Miharamachi work within the agriculture industry as farmers and the tendency to produce and consume vegetables from the area is thought to be high.

What can be deduced from this is that without a regular intake of contaminated food products, there is little if any increase in the level of internal radiation exposure. It also suggests that a majority of food products from areas of high soil contamination were not as contaminated as first thought.

Professor Hayano comments, “Results have shown that even the minority of people whose radiation exposure was high can reduce or eliminate exposure through regular health monitoring and avoiding contaminated food.”

High levels of internal radiation exposure were reported for many years after the Chernobyl nuclear explosion. However, Fukushima’s strict policy on the circulation of food products and thorough inspections have acted effectively in virtually eliminating this problem.

This result carries considerable implications not only for Japan on a domestic scale but also internationally as well. It all has to do with the line of thought that became prominent after the Chernobyl explosion which suggests that the degree of internal radiation exposure has to do with the length someone resides in a polluted area.

Applying this principle to Fukushima, it is natural to estimate that for a highly polluted area like Koriyama, the level of a person’s cesium 134 and 137 radioactive intake would reach figures of around 5 millisieverts. However, the actual levels of intake were considerably less. It is the first time that this type of contradictory evidence has come to light.

In fact, up until the announcement of this latest thesis, theses produced by Japan which analyze the correlation between internal radiation exposure and radioactive pollution have been surprisingly lacking. The World Health Organization (WHO) has produced two reports into the possible effects on the body of living in a highly polluted area. However, figures are based on predicted worst case upper limit radiation levels and are not taken from any actual data from within Fukushima.

It has been confirmed that this latest thesis will also be used as a reference to the United Nations Science Committee’s investigation (UNSCEAR) into effects of radiation which is due to be carried out this summer. It is hoped that this report will help to raise new levels of awareness into the effects of radiation on an international scale.

According to the Ministry of Health, Labor and Finance, the number of food inspections related to radioactive contamination carried out since the nuclear catastrophe come in at 40,000 cases. The number of food products that exceeded the safety limit totaled 10%. Breaking this figure down further, of 10% of food stuffs that exceeded the safety limit, only 2% reached contamination levels of 100 becquerels per kilogram.

In addition, Fukushima Prefecture, Japan Agricultural Cooperative, and the Fishermen’s Cooperative are also carrying out their own independent tests into radioactive contamination. The results have seen most products fall within the limit deemed safe for public consumption. In spite of this, there still remains a deep-rooted fear regarding radioactive contamination within Fukushima.

If the facts from this latest thesis are accepted by the international community, it is hoped that the negative rumors relating to contamination can at last be dispelled. The residents living in the prefecture can then begin to put behind them any fears about their future and their home towns.

Source: Shukan Diamond

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