I was asked by one of my friends what I would think of this recent article in Nature, stating that farming in Fukushima would not be affected too much. Here is my response.
I think that when we are given analyses by nuclear "experts", we have to be at least cautious about who they are and what position they take regarding nuclear energy. This is just FYI, the scholar who presents this optimistic analysis, Tomoko Nakanishi, is an official nuclear promoter. As this youtube clip shows, she was a member of Nuclear Renaissance Council, the nuclear promoting group consisting of electric companies, trading companies, mass media, ex-ministers of national government, and scholars. This clip was taken on February 17th in which Ms. Nakanishi explicitly stated that nuclear energy is "useful". (She actually talked about the possibility to take out "useful" materials like Ruthenium from nuclear wastes, instead of just burying them).
This is what I have learned with such a disappointment, but when it comes to nuclear energy, most of experts, especially those affiliated with University of Tokyo are indeed nuclear promoters. If you take a quick look at which scholars hold positions in organizations funded by the gov and energy companies, it is too obvious. (On the other hand, there is a group of nuclear scholars in University of Kyoto, who have been against nuclear energy with their expertise. And despite their decades of career, all of them remain "assistant professors".) Therefore we have to be aware of possible biases in what experts say: if they tend to underestimate the risk, under/overvalue the data? etc.
I think this article presents irresponsibly inadequate analysis on the risk of radioactive contamination.
What I found problematic in the article are regarding:
1. whether the governmental standards of food and soil contamination is trustworthy
2. confusion and misunderstanding (intentionally or unintentionally) over difference between external and internal exposure, and their respective risks
3. lack of argument regarding health risk of farmers
Let me clarify these points.
1. Yes, the gov set the radioactive "Caesium" standards for food consumption on 500bq/kg on March 17th, a week after the 3/11. Now one thing we have to note first is that this is talking about Caesium only, not about other radioactive substances. A research team of Kanazawa University found Plutonium in soil OUTSIDE of Fukushima Nuclear plant on June 5th. Even if it was a very small amount (0.078bq/kg), this means that Plutonium did leak from the plant to the environment (it can be still leaking to the environment most possibly to the ocean via drainage, but also to the air given that the ceilings of plants were brown out and remain still.) So did Strontium, Uranium, Curium and Americium. These are highly toxic radioactive substances, and Plutonium, Curium, and Americium do not exist in natural environment. Articles like this one often take only one or two radioactive substances out of many, which I personally feel as attempts to minimize risk evaluation.
Secondly, even if we talk about only Caesium, whether or not 500bq/kg is an appropriate standard is another issue. For example, based on Chernobyl experience German Society for Radiation Protection issued a recommendation to lower the numbers for infants to 4bq and for adults to 8bq. If not that strict, just take the pre-Fukushima standards in Japan itself, which banned the imports of food whose level exceeded 370bq. Another example is the standard for drinking water. Until the current standards (btw, because Japan did not have a law to specify radiation standards in food, current standards is actually a "tentative guideline", not a law) by which the Iodine level and Caesium level are not to exceed respectively 300bq and 200bq, Japan had employed WHO standards in which both Iodine and Caesium level was limited to 10bq. These show how arbitrary the current standards were set. Moreover, I would like to emphasize how secretively the current standards were set. I omit the details but this major change of radiation contamination standards was issued by Ministry of Health and Welfare as a notice, not as a law, and it was not covered in any major media at all.
2. It is the most annoying, and I personally think guilty, tendency that the most of mass media intentionally mix up external and internal exposure and their respective risks. What you can measure by Geiger counter is the amount of radiation by which you can talk only about the risk of external exposure. For example mass media still compares the monitoring data of radiation with X-ray or cosmic radiation during flights and concludes it is not harmful for human health. Well, if we think about the risk from external exposure only, that may be a case sometime. But what is completely missing from these kinds of arguments is the risk from internal exposure which is more serious and
present danger for those who live in the place where nuclear plants were exploded and still could not be stopped its radioactive emission.
Thing is that there are radioactive PARTICLES in the environment, air, soil, and water, and however small amount if those particles got into one's body, its effect on human health is incomparable with external exposure, for a)it means that one gets exposed to radiation from highly close distance (it's almost zero distance!), b)it takes time for those particles to be eliminated from the body, meaning for months, or even years depends on what kind of substance, one will keep getting exposed continuously, c)one gets exposed to all alpha, beta, and gamma rays, comparing to case of external exposure which is caused almost only by gamma ray, d)it is very hard to measure how much one gets internally exposed. To measure you will need a Whole body counter, which exist only about 10 units in whole Fukushima prefecture.
This is why food contamination matters the most. This article obviously neglects the danger of internal exposure DESPITE its talking about the amount of existing radioactive substance (bq/kg), not the strength of radiation effect on human body (sv/hr or sv/yr). To note, in case of Hiroshima and Nagasaki, people who were in 3.5 km from ground zero are qualified as radiation victim and can receive official compensation. Radiation level of 3.5km radius was equivalent to 1msv/yr, although this number again can only talk about external exposure. But compare this number to the level to limit Fukushima schools to open, 20msv, issued on April 19th. Namely, Fukushima kids are said to be OK (thus will not be compensated) to be exposed to 20 times as much radiation as Hiroshima and Nagasaki victims.
BTW, ICRP (International Commission on Radiological Protection) recommends Linea No Threshold Model which is employed internationally, that concludes that the risk of exposure is proportional to the amount of radiation at all level. Namely, there is no threshold level of exposure under which radiation has no effect on human body.
3. So, I think now it is clear from point 1 and 2, what I think is the most problematic in this type of article. It does not consider the risk of internal exposure for farmers AT ALL. "Under the standard" means very little, given that there exist radioactive particles in the soil, and that farmers are indeed a high risk group for their daily continuous contact with contaminated soil. By inhaling the dust, from wounds on hands, from the gap between fingers and nails, particles can possibly enter into farmer's body. And as I said in 2, while the effect of internal exposure is incomparably serious, how much one gets internally exposed is very hard to be measured.
You can say to farmers that you may keep working on that soil for its radiation level is below the standards, and maybe farmers would take it as a good news. But I feel it is almost deceiving, at least to me unethical, to give them a "fake" good news without telling them all information and risks regarding internal exposure. That is why I support to migrate young farmers to Western Japan, instead of buying produces from Fukushima and surrounding area. Because buying those produces indirectly leads to have farmers stay and work on high-risk soil. But, as I said, this should be applied to young farmers, not all farmers, for the risk of radiation depends on age group. (Look at this chart retrieved from here) In principle, the older, the lower the risk will be. I think it will be many cases for old farmers that they don't want to move out from familiar lands and to start from scratch in new place. But even if young farmers do miss their own lands, too, they should know, or more correctly, have rights to know, how high risk they are going to take by remaining there.
The latter part of this article appears more reasonable to me. Phytoremediation would absorb only Caesium-137 and Strontium. Not other substances. And we still have to deal with radioactive sunflowers and canolas afterwards. Indeed, as this picture shows, even if we could scope out surface soil, we do not know where those scraped soil should go. There is no definite way to safely dispose radioactive materials.
Just yesterday, Ministry of Environment started to considering to raise the limit of radiation level for burying radioactive wastes from 8,000bq to 100,000bq. Because now radioactive wastes whose level exceed 8000 are all over in Japan, under the current regulation they cannot do anything with them. At the same time, City of Fukushima is planning to scrub every building and road, which will take 20 years to get done. Of course they have to take care of tons of debris and contaminated water that will come off during this mission.
That's how desperate the situation is. And again, the radioactive emission is still ongoing.
I want to be optimistic. How badly I want to be optimistic! But, the more I learn, the more I regretfully
realize that optimism cannot solve anything in this situation. It does not mean I am panicking or giving
up on everything in Japan. What I believe is that we have to evaluate the risk cautiously and to take
responsible and practical measures for that. When they talk about food and soil contamination, they
often talk only about its risk for consumption, but what we really have to think about is health risk of
farmers, who are the most neglected high risk group.