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Radiation and Children Section 5: How can We Recognize the Effect on Human Health Caused by the Quake-stricken Fukushima Nuclear Plants?


Keywords: cancer, health, nuclear power plants, children, radioactive iodine, radiation, thyroid, thyroid cancer, leukemia, Great East Japan Earthquake, Toshiya Inaba


Don't panic; don't be misled by false rumors!

We finally saw out the year 2011, the terrible year with one of the biggest earthquakes on record in the world. However, there are still many people who evacuated from towns and villages near the quake-stricken Fukushima nuclear power plants, with still no idea when they can go back to their hometown. The constant stream of news from the media about the radioactive pollution of agricultural products never seems to stop.

Since last April, shortly after the nuclear accident, we have published a series of "Radiation and Children" from Section 1 to Section 4 on the CRN website, stating that there would be no substantial damage to human health caused by radiation. About one year has passed since then, and fortunately we won't need to change our opinion so far.

Nonetheless, there are many false rumors flying around the Internet and the media that claim, for example, that a fisherman who used to eat fish out of the river in the Fukushima prefecture died of leukemia or increasing numbers of people suffer from cancer in the Tohoku district, etc., etc. There even appeared someone pretending to be the chairman of the Japan Medical Association spreading a harmful rumor about the unusual increase of cancer. The mass media reported a statement by the association denying such a rumor, which had the adverse effect of making this incident widely known, causing disturbance to the public and heightening their anxiety.

But don't panic. Cancer is a common disease in Japan as almost half the population will develop cancer in their life time (!). What we have to see is that whether the nuclear accident actually increases the number of cancer patients. In this section, I will explain the possibility, when and how it will happen if it is going to happen, and how we will know the outcome. I hope this will help to reduce your fears or anxiety caused by groundless rumors.

Leukemia and thyroid cancer can be caused by massive amounts of radiation doses

First of all, there are two types of cancer that can be caused by radiation: (1) leukemia and (childhood) thyroid cancer; and (2) adult solid tumors such as lung cancer, bowel cancer and breast cancer.

Since leukemia and thyroid cancer are relatively rare, their increase rate may be immediately noticeable. In the cases of Hiroshima and Nagasaki, people living there had been exposed to significant radiation doses due to the atomic bomb. As a result, considerable rates of leukemia in these areas began to be reported from two to three years after the bombing, which no one can ignore. In the case of Chernobyl, an increasing number of thyroid cancer patients were also reported two to three years after the accidents (please see Section 4).

If the radiation dose is quite large (to be fatal or almost fatal) and given in a short period of time, it will cause leukemia. Likewise, thyroid cancer can be caused due to the local exposure to high doses of radiation; or more precisely, by absorbing massive radioactive iodine into the thyroid gland. These findings are supported by sufficient evidence based on a great deal of animal and in-vitro experiments.

In the case of Fukushima, there are no reports that any persons have been exposed to massive doses of radiation in a short time. Therefore, there seems very little possibility, due to the accident, that there will be a significant increase in the incidence of leukemia or thyroid cancer.

If the increase in ordinary types of cancer is expected due to the accident, it will happen after decades

It was around 1970, a couple of decades after the atomic bomb, when some ordinary types of adult cancer such as lung, bowel and breast cancer began to increase in Hiroshima and Nagasaki. This phenomenon occurred much later than that of leukemia. Unlike leukemia and thyroid cancer, these types of adult cancer are common in Japan thus, it is quite difficult to grasp immediately the actual rate of increase in such cancer.

Then how do we know about the increase? As I mentioned in Section 3, this is because more than 12,000 volunteers who survived the aftermath of the atomic bomb participated in the intensive research, started over half a century ago by the Radiation Effects Research Foundation.

In the case of Fukushima, it is estimated that the increase in adult cancer will occur a couple decades later if it is going to happen at all, but the rate of increase will be quite low. I am in my mid-fifties now, so I am unlikely to see the outcome.

The result of medical checks may give a false indication that cancer is increasing

Currently, all children in the Fukushima prefecture are receiving thyroid tests. This intervention is good but at the same time it could prove misleading, giving a false indication that thyroid cancer is increasing among children. It is a bit complicated, but I will try to explain.

It is said that people who are having regular cancer screening tests such as public health checkups are more likely to be diagnosed with cancer than those who are not. This sounds reasonable, but in fact it is not. Cancer is (believed to be) a potentially fatal disease if it is neglected and left to grow; therefore, a person who has cancer will be diagnosed with cancer eventually even if he/she does not have the regular test.

Furthermore, frequent cancer testing should reduce fatalities as this leads to early detection, but strangely enough this rarely happens. There are many people diagnosed with cancer through screening tests, but cancer fatality rates remain unchanged. This phenomenon can often be seen in the screening tests for lung, gastric, prostatic and ovarian cancer as well as neuroblastoma, a kind of childhood cancer.

There have been arguments to explain such a phenomenon; one is that there are two types of cancer, a "true" cancer potentially fatal if it is neglected, and a "quasi" cancer which can be neglected. Screening tests detect more "quasi" cancer rather than "true" cancer; thus, it looks as though many people are diagnosed with cancer through the tests, but in fact, it is still difficult to find a "true" cancer in the early stage. This is why the fatality rate remains unchanged.

Therefore, in the case of Fukushima children, there will be many cases diagnosed with thyroid cancer as a result of thyroid tests. Nevertheless, it is important to examine the results carefully from various angles in order to determine whether the increase in thyroid cancer is actually due to the accident.

No such thing as a sensational scoop!

In any case, the radioactive impact of the Fukushima nuclear accident on the increase in cancer rates should be assessed based on scientific research and analysis and made public by reputable universities and research centers.


Toshiya Inaba
Professor and Vice Director of Hiroshima University Research Institute for Radiation Biology and Medicine, Doctor of Medicine.
Graduated from Tokyo University Medical School. After employment at Saitama Children’s Medical Center, St. Jude Children’s Research Hospital, Jichi Medical University School of Medicine, appointed Professor, Hiroshima University Research Institute for Radiation Biology and Medicine in 2001, and Vice-Director since 2009. Specializes in hematology (mechanism of the onset of leukemia, pediatric hematology), microbiology, and radiation biology.
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