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A Japanese person wrote in her diary today that her English tutor told her that a lot of people in Japan have got cancer due to the Fukushima daiichi nuclear accident, and were already dead last year (2012) because of it.

Is this the case?

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    Sounds unlikely, cancer usually develops slowly – at least initially. – Konrad Rudolph Apr 6 '13 at 14:36
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    @Andrew Grimm: please link to the claim. I am sure lots of Japanese people write their diary daily, that does not mean what they write is worth investigating... :) – nico Apr 6 '13 at 14:47
  • @nico the diary doesn't have a lot of information, and her diary can't be read by non-members of the social networking site it's on. I've asked her whether the claim can be seen on the internet. – Andrew Grimm Apr 6 '13 at 23:08
  • (FWIW, the person writing the diary is an adult, not a schoolchild. That makes the peddling of misinformation slightly less odious, and as it wasn't made in a class containing lots of students, slightly less notable) – Andrew Grimm Apr 6 '13 at 23:13
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It doesn't seem that any cancer victims have yet been identified. The probabilities are low and are assessed over the whole lifetime of people in the worst affected areas.

It won't be possible to identify specific people whose cancer is attributable to the Fukushima Daiichi accident. At best, large scale studies may be able to measure the small increase in the actual numbers of cancer victims compared to the numbers who would normally develop cancer.

According to a World Health Organisation report in 2013 on the 2011 accident.

Outside the geographical areas most affected by radiation, even in locations within Fukushima prefecture, the predicted risks remain low and no observable increases in cancer above natural variation in baseline rates are anticipated ...

In the two most affected locations of Fukushima prefecture, the preliminary estimated radiation effective doses for the first year ranged from 12 to 25 mSv. In the highest dose location, the estimated additional lifetime risks for the development of leukaemia, breast cancer, thyroid cancer and all solid cancers over baseline rates are likely to represent an upper bound of the risk as methodological options were consciously chosen to avoid underestimation of risks. For leukaemia, the lifetime risks are predicted to increase by up to around 7% over baseline cancer rates in males exposed as infants; for breast cancer, the estimated lifetime risks increase by up to around 6% over baseline rates in females exposed as infants; for all solid cancers, the estimated lifetime risks increase by up to around 4% over baseline rates in females exposed as infants; and for thyroid cancer, the estimated lifetime risk increases by up to around 70% over baseline rates in females exposed as infants. These percentages represent estimated relative increases over the baseline rates and are not estimated absolute risks for developing such cancers. It is important to note that due to the low baseline rates of thyroid cancer, even a large relative increase represents a small absolute increase in risks.

I think the 70% increase for thyroid cancer risks for women means that for every 100,000 young girls in the most exposed areas, instead of say 5 getting thyroid cancer sometime in their lives, there would be around 8.

See Cancer Research UK for variations in rates between countries/regions.

Something of the order of 170,000 people were evacuated (Ref) from around the plant (the number of people displaced by the earthquake and tsunami was more). Not all those 170,000 were from the most affected areas (the initial evacuations were around 5,800 people) and, of course, not all of them were young girls.

Not everyone who gets thyroid cancer dies, the five year survival rates vary from 100% to 51% (ref) depending at which stage it is detected.

The only deaths in the WHO report are of seven workers

None of the seven reported deaths among workers is attributable to radiation exposure. The causes of these deaths have been reported as disaster-related (two cases), heart attack (three cases), sepsis (one case) and leukaemia (one case for which the time of the onset was shorter than the minimum latency period for radiation-induced leukaemia).

Consequently, it is unlikely that any additional deaths have yet occurred in the wider population.


Update: Three years after the Fukushima disaster.

The BBC reports that 33 cases of thyroid cancer have been confirmed in 260,000 children studied. The report does not make clear how many cases would have been expected normally.

Professor Shinichi Suzuki leads the team studying the children of Fukushima. ...

"In Japan there has never been a survey on this scale done before," he said. "Once you start using very sensitive equipment to check for thyroid cancer in a very large group of children then you will inevitably find an increase in the number of cases. That is why we are seeing the increase now. These cases are not related to the nuclear disaster." ...

he and other experts now say they think there will be very few, or even zero, extra childhood cancers because of Fukushima.

Still no deaths reported (that I can find).

Tally so far:

  • Deaths from earthquake and tsunami: 15853-18000.
  • Deaths from subsequent stress: 1656.
  • Deaths from radiation: 0.
  • It's difficult to see how the last paragraph addresses the question. It just gives the impression you have an axe to grind. – Relaxed Mar 11 '14 at 10:55
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    @Annoyed: I thought some context might be useful. I take your point though. – RedGrittyBrick Mar 11 '14 at 11:32

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