Saturday, September 10, 2016

Confusing Correlation with Causality in Fukushima Children's Thyroid Cancer Rates and Radiation Exposure

Although 112 children have been diagnosed with thyroid cancer, officials from Fukushima Hopsital, who are conducting the Fukushima Health Management Survey, contend that radiation exposure had NO EFFECT on the escalating incidents of thyroid cancer:
Teru Okumura. September 10, 2016. Study draws a blank on thyroid cancer and 2011 nuclear disaster. The Asahi Shimbun,

Researchers have found no correlation between radiation exposure and the incidence rate of thyroid cancer among 300,000 children living in Fukushima Prefecture at the time of the 2011 nuclear disaster.

But the team at Fukushima Medical University, which carried out the study, cautioned that the health of local children should continue to be monitored to be more definitive.

“At the present stage, we have found no evidence pointing to any relationship between doses of external radiation resulting from the nuclear accident and the thyroid cancer rate,” said Tetsuya Ohira, a professor of epidemiology at the university. “But we need to continue to look into the situation.”

The idea that there is NO CORRELATION is entirely preposterous. Of course there is a CORRELATION. Children exposed to Fukushima fallout in areas near the plant have a higher thyroid cancer rate than found in other places.

Efforts to deny the correlation tell you pretty much everything you need to know about the objectivity with which this story is reported.

The question is whether there is a CAUSAL RELATIONSHIP. 

I believe there is a causal relationship, as do other scientific observers. However, proving that causal relationship is going to be tough since data on children's earliest exposure was erased and because radiation monitoring badges weren't given until June 2011, months after the disaster.

Below find an excerpt from some of my written work on this subject:

The debate about Fukushima’s exposure effects has focused on the reasons for rising thyroid cancer rates in Fukushima Prefecture children. Chaotic evacuations because of poor crisis communications in March of 2011 interfered with distribution of potassium iodide, which blocks absorption of radioactive isotopes of iodine.[i] Fukushima emissions included substantial Iodine-131 particle and gaseous emissions.

Radioactive forms of iodine are easily absorbed into the thyroid gland and were widely acknowledged to have caused cancer in children directly exposed to Chernobyl fallout.[ii]

Comprehensive surveys of Fukushima children conducted by Fukushima University Hospital and by other physicians in Japan have documented high rates of thyroid nodules and cancers in Fukushima children, leading one group of researchers to report a link between exposure and thyroid cancer, with the rate up to 50 times higher than ordinarily found in childhood populations.[iii]

As of August 2015, the Fukushima Prefecture Government identified 104 thyroid cancer cases in the prefecture.[iv] However, other authorities contest the link because there exists no definitive data about children’s exposure levels since they were not given radiation monitoring badges until June 2011, months after the accident occurred.[v]

The debate is illustrated in a news report published in The Japan Times, October 2015 that covers the competing accounts of spiking thyroid cancer. In the news report, allegations that spiking thyroid cancer rates were caused by Fukushima fallout is refuted by Shoichiro Tsugane of Japan’s National Cancer Center, who claims that no cause can be attributed to the children’s cancer in the absence of specific data on their radiation exposure:
“Unless radiation exposure data are checked, any specific relationship between a cancer incidence and radiation cannot be identified,” said Tsugane, director of the Research Center for Cancer Prevention and Screening. New report links thyroid cancer rise to Fukushima nuclear crisis Kyodo Oct 7, 2015
Establishing definitive linkages between thyroid cancers and exposure may be impossible because, as reported by NHK in August of 2011, Japan’s nuclear commission had erased children’s exposure data derived from a test of 1,000 children aged 15 or younger who had been screened for radiation affecting their thyroid.[vi]


[i] Y. Hayashi (29 September 2011) ‘Japan Officials Failed to Hand Out Radiation Pills in Quake’s Aftermath’ The Wall Street Journal,, date accessed 30 September 2011.

[ii] Chernobyl Forum (2006) Chernobyl’s Legacy: Health, Environmental and Socio-Economic Impacts and Recommendations to the Governments of Belarus, the Russian Federation and Ukraine,, date accessed 20 August 2012.

[iii] Tsuda, Toshihide; Tokinobu, Akiko; Yamamoto, Eiji; Suzuki, Etsuji, Thyroid Cancer Detection by Ultrasound Among Residents Ages 18 Years and Younger in Fukushima, Japan: 2011 to 2014,” Epidemiology: (October 2015): doi: 10.1097/EDE.0000000000000385
[iv] New report links thyroid cancer rise to Fukushima nuclear crisis Kyodo Oct 7, 2015
[v] Junko Ogura “Japan to Hand Out Radiation Meters To Kids Near Crippled Plant,” CNN (2011, June 14):

[vi] “Nuclear Commission Erases Children's Exposure Data,” NHK (2011, August 11):


  1. Those are brazen pimps for nuclear. They should be given Nuremberg trials.

    Physician, first do no harm, tell no lies.

  2. Suggest you read the study

    Tsuda study does not stand up to critique

    1. I read the study and find the methodology to be based on assumptions about EXTERNAL exposure that are problematic and exclude effects of internalized radioactive elements through inhalation and ingestion.


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