Don your lead-lined tinfoil hats – Fukushima children’s thyroid cancer

Japan Times is one of the many newspapers to carry this Kyodo report on "three young people have thyroid cancer". The fact of the matter is:

A Fukushima Prefectural Government panel said Wednesday that two people who were 18 or younger when the triple-meltdown crisis started at the Fukushima No. 1 atomic complex in March 2011 have been diagnosed with thyroid cancer, bringing the total cases to three.

Kyodo also reports that a professor on the panel said:

Reporting at a meeting on the health impact from the catastrophe, professor Shinichi Suzuki of Fukushima Medical University said it is too early to link the cases to the nuclear disaster, because it took at least four to five years for thyroid cancer to be detected after the Chernobyl meltdown calamity that started in 1986.

However, if we look what might be the Japanese version of the Kyodo story on Yahoo! via the Mainichi, we see:

鈴木教授は「元々あったものを発見した可能性が高い。(原発事故との因果関係は)考えにくい」と語った。

That’s quite a different emphasis. However the same professor also said this:

子どもの甲状腺がんの発生率は「100万人に1人」が通説。

Surely the prof would have an exact figure, rather than passing on "one in a million"?  A comment on Japan Times provides a link to UK child data, so taking the 15 to 19 year old band, it is about sixteen in a million. However, scaling up the tests in Fukushima, 3 in 38,000, we get about eighty in a million. This is about five times higher than the expected UK rate, but if we stick with three people instead of perhaps zero or one people in an "average" year, the change may be either an expected statistical fluctuation (I don’t know the maths to do to demonstrate that!) or caused just by the increase in thyroid tests.

It’s also interesting to note that there has already been 43 retweets of this article, many of them the usual anti-nuclear crowd.

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12 Comments.

  1. Asahi.com is saying the there are 7 additional cases that are suspect:

    http://www.asahi.com/national/update/0213/TKY201302130390.html

    Some are claiming that the 4-5 year lead time for evidence of this with respect to Chernobyl is because all the original data was either not collected or “disappeared” before that time.

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  2. @Ken

    Am I reading the UK data wrong? I get a yearly rate of 440 per million aged 0-19 on the UK data. (But that would mean the Fukushima rates are rather lower than expected.) It’s late thoughbut and I think I must have missed something.

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  3. @chuckers:

    I could be wrong, but I highly doubt that the epidemiologists involved in the UN Chernobyl studies would have overlooked whether or not data was being collected in the first couple of years. It sounds like something made-up for propaganda: a problem easy enough for the layperson to understand rather than one that professionals would have plausibly missed (cf climate change denial).

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  4. @VK: Do you think that sort of thing matters to those that really want to believe?

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  5. @VK:

    Yep, I read that wrong. /infant insomnia\. Three cases in 38,000 is unusual.

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  6. Now I’m more awake, this is what it looks like to me:

    I think Suzuki either mispoke or has been misquoted about the one in a million remark. In the 15-19 age range, the rate of naturally occurring thyroid cancer/100,000/year in the UK is 1.2 for girls and .4 for boys. This pdf from Fukushima Medical University states that rates in Europe/America and Japan are the same, citing 0.2 per 100,000 for under fourteens – which matches the UK data, and directly contradicts Suzuki’s reported statement. So I think we should use the UK figures for an age breakdown if no one can find a good breakdown for Japan by age.

    As for the numbers: Asahi quotes 180,000 under-18s, while Kyodo in JT says 360,000 under 18s and Mainichi says 360,000 people (but implies they are children). If it’s 360,000, a rough and ready calculation suggests that overall and conservatively, we’d probably see 2 or 3 cases over all the children over two years anyway. (The demographics are also biased towards the higher age group, what with the low birth rate.) We’d also expect them to be in the higher age group if they’re naturally occurring.

    It’s being reported that these cases have been found in the 38,000 examined. Which makes me ask – what about the other cases that should have presented anyway? Are these in addition, or have the journalists got confused, or did the expected cases just happen to turn up in this small group?

    If there are actually ten cases (Asahi/Mainichi said there’s an 80 per cent chance that the other seven have thyroid cancer), this is very high. Yet Suzuki is reported as saying “the possibility that these cancers were there [prior to the accident] is high”. So I wonder if the journalists’ version has been tweaked somewhat. (Interestingly, Asahi failed to include Suzuki’s quote on this bit.) Suzuki seems to think what we’re seeing is not particularly out of the ordinary.

    What I don’t know is what we would expect to find if we scanned a population at one go. How many cancers that would have clinically presented later have been discovered early? (Have we concertina’d the next few years of thyroid cancers in one go?)

    How does all this compare to Chernobyl? The age pattern doesn’t seem to fit the profile of radiation. Thyroid sensitivity to radiation is higher in younger children. This paper comparing Chernobyl-exposed populations and non-exposed in western Europe has a diagram showing how much younger children were diagnosed earlier.

    The same paper notes that ordinarily we would get 2.5/1 rates of female-to-male thyroid cancers (similar to the 7/3 ratio here) and presenting older, rather than the 1.6/1 ratio found in Belarus). We have small numbers here, of course, but it seems worth mentioning.

    Regarding the suggestion that thyroid cancers weren’t measured: this is simply made-up anti-nuke nonsense (check the user’s disqus comments):

    Between 1986 and 1989, the number of thyroid cancer cases per year ranged from 3–8 and increased to 31 in 1990, to 66 in 1991, to 72 in 1992, to 93 in 1993, to 96 in 1994, and to 90 in 1995.

    We know that level of exposure is related to the possibility of developing cancer, so we simply shouldn’t expect a rise faster than that which occurred in Chernobyl – where the average exposure was around four times higher than the highest estimate for people in the most exposed area.

    In short, if there are suddenly a lot of cases so soon after the accident, with such low exposure and in that age group and with that gender profile, It doesn’t fit the pattern of what we know about radiation and thyroid cancer.

    That said, I may still be being dopey with the numbers.

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  7. I posted a clarification about the discrepancy between the English and Japanese last night, but it hasn’t got past the JT filter yet… :sad:

    I also got some clarification of the numbers for the statistical-deficient from StackExchange. :cool:

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  8. @Ken Y-N:

    You didn’t put any kanji in the comment, no? JT Disqus moderation has a English only rule; if you must compare with Japanese, use romaji.

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  9. I see Captain Mainwaring has nobbled the silliness about the “44% of children have thyroid nodules” research before I could get there.

    He’s rather more effective than his namesake.

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  10. I can’t believe we’ve managed to go so long without a visit from a certain someone…

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  11. @crowfoot:

    Speaking of which, I think this seems very similar to our JapanTraveller,

    http://www.documentingian.com/

    At the very least it’s someone who sees human distress as a career opportunity.

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  12. @VK: Ah yes, I did see that and think of the similarity too.

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