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32,000 workers at Fukushima No. 1 got high radiation dose, Tepco data show

JIJI

A total of 32,760 workers at the Fukushima No. 1 nuclear plant had an annual radiation dose exceeding 5 millisieverts as of the end of January, according to an analysis of Tokyo Electric Power Co. data.

A reading of 5 millisieverts is one of the thresholds of whether nuclear plant workers suffering from leukemia can be eligible for compensation benefits for work-related injuries and illnesses.

Of those workers, 174 had a cumulative radiation dose of more than 100 millisieverts, a level considered to raise the risk of dying after developing cancer by 0.5 percent. Most of the exposure appears to have stemmed from work just after the start of the crisis on March 11, 2011.

The highest reading was 678.8 millisieverts.

Overall, a total of 46,490 workers were exposed to radiation, with the average at 12.7 millisieverts.

The number of workers with an annual dose of over 5 millisieverts increased 34 percent from fiscal 2013 to 6,600 in fiscal 2014, when workloads grew to address the increase in radiation-tainted water at the plant. The number was at 4,223 in the first 10 months of fiscal 2015, which ends this month, on track to mark an annual decline.

A labor standards supervision office in Fukushima Prefecture last October accepted a claim for workers compensation by a man who developed leukemia after working at the plant, the first recognition of cancer linked to work after the meltdowns as a work-related illness. Similar compensation claims have been rejected in three cases so far, according to the labor ministry.

The average radiation dose was higher among Tepco workers at the plant than among workers from subcontractors in fiscal 2010 and 2011. Starting in fiscal 2012, the reading was higher among subcontractor workers than among Tepco workers.

The average dose for subcontractor workers was 1.7 times the level of Tepco workers in fiscal 2013, 2.3 times in fiscal 2014 and 2.5 times in fiscal 2015 as of the end of January.

A separate analysis of data from the Nuclear Regulation Authority showed that the average radiation dose of workers at 15 nuclear power plants across the country, excluding the Fukushima No. 1 and No. 2 plants, fell to 0.22 millisievert in fiscal 2014, when none of the plants was in operation, down 78 percent from 0.99 millisievert in fiscal 2010.

  • Sam Gilman

    When I saw the headline, I presumed that “high dose” was something approaching 100mSv.

    It turns out to mean nothing of the sort. 5mSv is low dose. There is no evidence that 5 mSv does anyone any harm. Combined average exposure in modern life is around 6mSv a year anyway (natural and human- made sources).

    There is a compensation threshold exposure of 5mSv if someone develops a condition that might be caused by radiation. But this threshold isn’t based in any actual assessment of cause. All that happens is that the person is investigated, and if no other lifestyle causes for the condition are found, they get compensation, even if the chances of radiation being the cause are very very slim. That is what happened in the leukaemia case mentioned here. No medical link was made at all. It wouldn’t be possible. Judging by the dose, it was very highly likely unconnected to working at the plant.

    Still, the headline made me click…

  • Sam Gilman

    When I saw the headline, I presumed that “high dose” was something approaching 100mSv.

    It turns out to mean nothing of the sort. 5mSv is low dose. There is no evidence that 5 mSv does anyone any harm. Combined average exposure in modern life is around 6mSv a year anyway (natural and human- made sources).

    There is a compensation threshold exposure of 5mSv if someone develops a condition that might be caused by radiation. But this threshold isn’t based in any actual assessment of cause. All that happens is that the person is investigated, and if no other lifestyle causes for the condition are found, they get compensation, even if the chances of radiation being the cause are very very slim. That is what happened in the leukaemia case mentioned here. No medical link was made at all. It wouldn’t be possible. Judging by the dose, it was very highly likely unconnected to working at the plant.

    Still, the headline made me click…

    • Roy Warner

      5mSv is not really alarming, but if we were to read the article, we would find: “The highest reading was 678.8 millisieverts.
      Overall, a total of 46,490 workers were exposed to radiation, with the average at 12.7 millisieverts.” I hear they’re hiring. Why not send them a resume?

      • Sam Gilman

        Yes, there are some people who have genuinely received high doses. But the headline does not mean these people. However, given your history of spreading misinformation on this topic, I am not surprised you want to defend it.

  • loreta

    what is 5 millisieverts for an ordinary reader.. no explanation is given, no comparatives, the comment below seems more comprehensive than the article..

    • Sam Gilman

      Hi Loreta,

      This chart is great. It has a lower figure for yearly dose (4mSv) than I cited (6mSv). I was using the figure for Americans from the NRC, but the number will vary geographically.

      https://xkcd.com/radiation/

      • loreta

        Dear Sam,
        Many thanks. It looks great. I will take a look at it with more detail. Best wishes,
        Loreta

        2016-03-08 11:12 GMT+01:00 Disqus :