“Radiation can’t be seen, but if you use a dosimeter you can see it in the form of numbers. By measuring radiation, you can remove unnecessary fear, and properly fear what should be feared.”
— Hirotoshi Sano, quoted in The Mainichi
Recently my Japanese teacher mentioned that people from Fukushima prefecture still suffer discrimination in Japan, because some people fear they might somehow distribute radiation. One of her relatives has observed this first hand when collaborating with a teacher from Fukushima for a series of lectures. I had heard about such discrimination before, but hearing that it is still happening pushed me to write about the topic again. While I was working on this post, The Economist published an article about the “Fukushima 50”, the workers who remained at the Fukushima Daiichi NPP at the peak of the crisis, and their troubles. I’ll add a post about the situation in Germany, which also makes me angry, when I find the right words for it.
Hirotoshi Sano survived the nuclear bombing of Hiroshima and later did research on radioactivity. Back in 1945, after the nuclear attacks on Hiroshima and Nagasaki, many survivors sought help from family and friends outside the cities, but those were often reluctant to take them in. News of the terrible illness that many survivors were suffering from had spread quickly, and as terrible as refusing help is, I can understand that people feared getting infected. However, today we know that the problem wasn’t a mysterious new illness, but radiation poisoning. The only way to get it is to receive a huge dose of ionizing radiation, and because there is no infectious material involved, it cannot be passed on. “Ionizing radiation” is a scientific term for radioactive radiation and some other kinds of radiation with similar effects.
Contamination, on the other hand, means that radioactive material is sticking to or inside one’s body. If it is on the skin or clothes (external contamination) it can be washed off easily. While internal contamination is more serious for the person concerned, it poses no threat to others. Actually, carefully controlled ingestion or infusion of radioactive isotopes is sometimes used to combat cancer, this is called radioisotope therapy.
The serious issue here is that people lack education on the matter, and then act out of fear. I want to be very clear that this is not a Japanese issue, but an international problem. At the end of World War II few people had heard of radioactivity. Today they could easily learn what radioactivity is and how it can affect the human body. But they often don’t. Many people don’t know that natural radioactivity (“background radiation“) is everywhere, and that the human body naturally contains certain radioactive isotopes. A few are even surprised to learn that our world is made of atoms. Yet they know radiation can be dangerous. Such an invisible danger easily causes fear, instead of a calm analysis of what is going on and what the danger is — if any. And this fear is a danger of its own: It can cause discrimination, stress, and psychological problems, which can lead to other medical conditions.
I’m not saying radioactivity is never dangerous. But if you don’t know already, please take the time to learn what it is and what it does!
Some numbers for perspective
When the earthquake that caused the crisis at Fukushima Daiichi happened on March 11, 2011, I was in Sendai, about 100 kilometers from the nuclear power plant. Three days later I left Sendai for western Japan to get some safety distance. When I returned in April the monitoring data from the Tohoku University Cyclotron and Radioisotope Center showed a radiation level around 0.08-0.09 µSv/h (microsieverts per hour). Now what does that mean? Before the disaster at Fukushima Daiichi NPP, the radiation level in Sendai was around 0.04 µSv/h. 0.09 µSv/h is more than twice that amount. Sounds scary? Actually, 0.09 µSv/h is the perfectly normal radiation level in Dortmund, Germany, where I currently live. Still many international students were scared of radiation and fled from Japan. By the time of this writing, the radiation level in Sendai has fallen further to about 0.06-0.07 µSv/h.
Current (October 5, 2012) measurement results published by Fukushima City vary between 0.13 µSv/h and 1.22 µSv/h. I’m not giving an average here because the data reflects various areas of the city (some of which have been decontaminated) and different kinds of ground and is thus hard to compare.
A study by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) says this about the radiation dose during flights, which is significantly higher than on the ground due to cosmic radiation:
“The more recent review of the exposure of aircrew [E1] indicates that the effective dose rate at an altitude of 8 km in temperate latitudes is typically up to about 3 μSv h-1. At 12 km, the value would be about twice this.”
On my flights to and from Japan the plane moved at an altitude above 10 km most of the time. Of course, I didn’t carry a dosimeter, but from the study I think is reasonable to assume a dose rate of about 5 µSv/h, which is about five times the highest level measured in Fukushima City, and more than 50 times the one in Dortmund. Still most people aren’t particularly scared of flying, and those who are usually fear height, not radiation.
Sadly, there is no clear answer to the question how much radiation is dangerous.
“Although radiation may cause cancer at high doses and high dose rates, public health data do not absolutely establish the occurrence of cancer following exposure to low doses and dose rates — below about 10,000 mrem (100 mSv). Studies of occupational workers who are chronically exposed to low levels of radiation above normal background have shown no adverse biological effects. Even so, the radiation protection community conservatively assumes that any amount of radiation may pose some risk for causing cancer and hereditary effect, and that the risk is higher for higher radiation exposures.”
The evacuation zone in Fukushima is designed to prevent exposure to more than 20 mSv per year, which is similar to the dose received from a full body CT scan. The highest level of natural background radiation in the world occurs in Ramsar (Iran) with an average of 1.16 µSv/h (source), which leads to an annual exposure of about 10 mSv.