After Fukushima, part 7

Pastor Nobumasa Tajima argues with his daughter Christine about whether it was unsafe after the Fukushima Daiichi disaster to let her children play in the grass beside the church. Nobumasa Tajima, a Japanese-American, runs the Koriyama Baptist Church with his wife Beverly.

What is safe?

It’s not hard to learn the current radiation levels across Fukushima Prefecture. You can hear them on the evening news, along with the weather, or read yesterday’s totals in the local paper. Outside many public buildings there are dosimeters showing current readings. (1)

What is harder to grasp is the meaning of all these numbers. In the past two years, the Japanese public has had a (new) crash course in radiation. The first question for many was Am I safe here?—can I breathe, eat, fish, swim, plant a garden, let my kids play outside? Unfortunately, there are only two honest answers to such questions: (1) Maybe, and (2) We don’t know.

Acute Radiation Sickness (caused by a high exposure in a short period) has a well-defined set of symptoms. However, for low-level exposure to radiation over a long period, it remains impossible to predict how any individual will be affected. Will some radioactive particle you ingested trigger cancer or not? It is all a question of probabilities, and there are too many variables and too little research to know.

One school of thought, the linear no-threshold (LNT) model, argues that there is no safe level of exposure—your risk is directly proportional to your dose. A competing view, the threshold model often used in toxicology, argues that minute exposures to radiation are harmless. In this view, the important question is determining what the safe threshold is. A third perspective, the radiation hormesis model, argues that radiation at very small doses is actually beneficial because it triggers cellular repairs.

In Fukushima, with no conclusive data available, residents are stuck deciding if the risk from radiation, in their personal assessment, is large enough to outweigh the definite costs of moving, such as loss of home, community and employment. Just as in Chernobyl, people under 35 are more likely to leave and say they will not return (2). Once you decide it’s not safe here, the next question is: where is safe?

Recently, as reported here, (3) there has been social pressure to assume that radiation levels in Fukushima are safe everywhere outside the Exclusion Zone, and to not ask too many questions. A consensus message that “all is well” will help the province economically, public officials have argued. Such optimism quiets protest but I have to assume it assuages few fears. 

Sources:

(1) Fukushima City website, Environmental Division. English translation.

(2) According to a survey in Futuba by Fukushima University, reported in Yomiuri Shimbun.

(3) Rocket News 24.

Tomorrow: Chernobyl quiz winners.