Japan: first report of radioactive contamination in rice

Agricultural inspectors in Japan's Ibaraki Prefecture have detected small amounts of radioactive cesium in a sample of rice farmed in Hokota city, about 100 miles south of Fukushima Daiichi nuclear plant. The prefectural government posted readings here, says the rice is safe: 52 becquerels per kilogram, or 1/10 the limit established for grain.

This news follows earlier disclosures that radioactive contamination has been detected in beef, milk, and other agricultural products from throughout the country. But no one food staple is more central to Japanese culture, diet, and identity than rice, and this news comes as fears grow about whether the 2011 harvest will be safe.

More: WSJ, NYT, and an op-ed in Daily Yomiuri calling for steps to secure the safety of Japan's national food staple. (Via Steve Herman)

(Image courtesy of the Ibaraki prefecture government website.)


  1. As far as I can tell from sources like http://www.physics.isu.edu/radinf/natural.htm  and some use of Wolfram Alpha, this is the equivalent of 0.4 kg of bananas. (52 bq/kg = 1405 pCi/kg).  I don’t know how it stacks up against a banana’s potassium as far as body absorption goes, though.

    Also, can we assume this is 1kg of uncooked rice? 

    In other news, brazil nuts are apparently pure death with 1,000-7,000 pCi/kg of Radium.

  2. “1/10 the limit established for grain”

    Well, if it is under the limit it is safe, no? Where is all the fuzz?

    1. Well yes but it does build up, and the point is that if they’re detecting it now it may continue to get worse if the soil in that area is contaminated. It takes years for this stuff to go away.

  3. I wonder how meaningful it is that a particular sample of rice from a particular area is found to have X level of contamination. Surface contamination both near and far from the plant seems to have been patchwork and variable. Measure the ground right here and there’s nothing surprising, then move ten meters over there and the reading is 10 or 100 times higher. The radioactive isotopes spread unevenly with the vagaries of wind and weather, not in perfect concentric rings around the reactors like TV news programs showed. The rice fields have accumulated whatever fell onto them. I just don’t see how these checks will correctly show what’s going on in the bag of rice that I buy, even if the checks are made properly and in good faith–which itself is often not the case around here.

  4. Ashen Victor: because legally safe does not always mean safe. When a nuclear emergency has been declared, as it has been in
    Japan, the government is permitted to redefine the level that is called “legally

    Example, for infants’ beverages in Japan, the current “legally
    safe” level of radioactivity has been provisionally increased to 100
    bq/kg. Apparently this is more than twice the international law standard
    for nuclear waste.

    For food, the current “legally safe” level of cesium 137 is 500 bq/kg.
    This is 3
    times the US number…and more than 10 times the number permitted in
    the Ukraine and Belarus–two places that have a lot of sad experience
    with the effects of internal emitters. There aren’t a lot of experts who
    will say this number is OK for you and your children. Here is a nice
    chart that some
    Japanese people posted awhile back:


    That being said, the 52 bq/kg found in this rice does not seem
    terrifying–if it is indeed a correct and accurate reading, and if it is
    representative of all the rice harvested in that area. Unfortunately,
    we have seen repeatedly that those two big “ifs” don’t always play out the right way.

    1. Good analysis. The problem is the next magnitude is somewhere in the 100x to 1000x.

      Since many Americans don’t understand SI units (and the metric system), the intuition of the granularity scaling is wrong leading to frequent overreaction over 2 or 3x …

  5. Our rice comes from the wife’s family farm here in Kyushu…and I’m damn careful to know where other groceries are from. My 2-yr-old daughter does not eat restaurant food or packaged food…these people are utterly incompetent when it comes to testing. They will ban radioactive spinach and sell the vegetables that grew in the same field because there is “no evidence there is a problem with anything but the spinach”…when asked if the other vegetables were tested, they hem and haw and say the other vegetables are not banned, so please buy them.

    Japan has destroyed its future and I no longer have much sympathy…they let it happen, they do not complain, and they trust people who have proven themselves untrustworthy. I plan to be gone in a year or so.

  6. “the rice is safe”
    So long as you ignore the advice of many health physicists that no exposure to ionizing radiation is “safe”.

    Easy advice to give: there’s a good chance that those giving the advice will be dead of natural causes by the time the misery shows up.

    1. So long as you ignore the advice of many health physicists that no exposure to ionizing radiation is “safe”.

      You’re being exposed to ionizing radiation right now. It’s in the air all around you. Hold your breath, quick! And whatever you do, don’t go out in sunlight. Or eat a banana.

      On a less insane note, your body is extremely well defended against low levels of radiation. Nothing you ever do in life is “safe”, and what matters is understanding the risks and accepting those which outweigh the costs of avoiding them. The risks of low levels of radiation are minuscule; the risks of not eating are, well, pretty much certain to kill you. (You’re rich enough to choose to eat whatever you like and test it all for chemical contamination? Lucky for you; why are you here?)

  7. That looks like unhusked rice (I live in Japan, and make rice every day)  The govt has large stores of rice from previous harvests, so we should all be fine if something horrible happens.  Also, we can import rice from thailand and china.  While a lot of people wouldn’t be happy because its not “nihon-sei” they would get over it if they didn’t starve to death!

  8. To put matters in even more perspective, the US legal limit for radioactive cesium in food is 170 bq/kg, but no such rule exists for the potassium in potato chips and bananas…because that is different. Google away.
    Also, while it’s true that the risks of low-level ionizing radiation are miniscule, a radioactive isotope is not “radiation”. The amount of radiation that an internal emitter bathes adjoining cells in is extremely high, causing cellular death and genetic mutation over and over.
    There doesn’t yet appear to be enough data to make definitive pronouncements on the level of risk from internal emitters. Complicating the assessment is the fact that the answer will depend on which isotope and where it lodged in your body–bone, brain, intestine, muscle, lung, liver, fat, etc.
    The Fukushima accident is a chance to improve the data and science on internal emitters by making extensive and controlled measurements and collecting as much data as possible on radioactive isotopes in the environment, food and body as well as long-term health outcomes–but unfortunately, the government and research bodies are not doing this at all. Without that data, thirty years from now we’ll see the same he said/she said posting wars where people dispute the actual number of deaths from Fukushima like they are doing now for Chernobyl: was it 18, or 1 million? And plenty of people will still say nuclear energy is safe and clean.
    It’s happening right now. Look at this Reuters article in which “radiation-free” rice actually means “not more than 200 bq/kg”… Great news…now even radiation is “radiation-free”. That’s how well things are going.

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