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Fukushima Fallout: How Dangerous Is Japan's Creeping Nuclear Disaster?

By , Takako Maruga and

Part 3: Just How Reliable Are the Radiation Measurements?

Photo Gallery: Learning to Think in Millisievert Photos

The Japanese will have to learn to think in terms of millisievert. For example, the highest reported hourly dose at the edge of the evacuation zone was 0.16 millisievert. A person who spends 25 days constantly exposed to such levels would receive the maximum permissible annual dose for workers at nuclear power plants.

There is also an underlying sense of uncertainty over just how reliable the radiation measurements actually are. And critics wonder why the highest radiation readings near Fukushima are usually taken by police personnel and not Tepco or the Japanese nuclear regulatory agency.

But even if suspicions are unfounded, the insidious aspect of radiation is that it is so unpredictable. "We will see a patchwork of areas of higher and lower radiation levels," says Peter Küppers of the Eco-Institute Darmstadt in southwestern Germany. The radiation level depends on wind direction, rain and where water collects. The differences were extreme after Chernobyl. "There were parts of northeast Bavaria and at Konigssee Lake in Germany that were more contaminated than some spots within the 30-kilometer exclusion zone directly surrounding Chernobyl," says Küppers.

Dispersal over such a large area can be practically ruled out in Japan. This only occurred at Chernobyl because the reactor burned for days, propelling radioactive material into extremely high air layers.

But where the fallout descends also depends largely on the wind in Japan. "At first Japan was very lucky, as far as the weather was concerned," says König of Germany's Federal Office for Radiation Protection. The sinister plumes initially drifted out to sea. But the weather gods will not always remain as merciful.

A Sense of Foreboding and Uncertainty

There is already a sense of foreboding among the residents of Fukushima. Yoshihiro Amano owned a small grocery store six kilometers from the nuclear power plant. Now he is waiting in line for a bowl of noodle soup in an evacuation center, trying to make the best of the situation. "There's no point in getting angry," he says. "But we are afraid. We don't know if it will take days, months or decades before we can go home again."

The Japanese will have to live with this uncertainty from now on, because our knowledge of the health effects of radioactive radiation is so appallingly slim.

Studies involving the survivors of Hiroshima and Nagasaki concluded that if 100 people received a dose of 100 millisievert, one of these people would eventually die of cancer as a result of the exposure.

This can certainly be seen as a comforting piece of news. On the one hand, it indicates that if about 40 of 100 Japanese would normally die of cancer at some point in their lives, that number would only rise to 41 among 100 people exposed to 100 millisievert of radiation. On the other hand, 100 millisievert is an enormous dose. To date, only a handful of workers in Japan have been exposed to such a bombardment of radioactivity.

But what about those who were exposed to lower levels of radiation? What if each of the 35 million residents of Tokyo is exposed to a few millisievert of radiation? There are few questions in science that are being discussed more heatedly, and yet there are no reliable answers.

'Any Amount Is Harmful'

One thing is clear: Even in the region surrounding Chernobyl, there has been no statistically significant evidence of elevated levels of leukemia and cancer following the accident. The one exception is thyroid cancer in children, for which there is clear evidence of a connection with the accident. On the other hand, there is no official lower limit at which radiation becomes harmless. "Any amount is harmful," says Edmund Lengfelder, director of the Otto Hug Radiation Institute in Munich. "And the younger the person, the more harmful it is."

Radiation poses the greatest danger to embryos in the womb during their earliest stages of development. Radiation can cause Down's syndrome, spina bifida, cleft palate and other birth defects. Genetic changes can also be passed on to the next generation, as DNA testing of healthy children of the workers involved in the Chernobyl cleanup has shown.

According to the results of a disturbing simulation just released by the Japanese nuclear safety commission, young children outside the 30-kilometer radius surrounding the damaged nuclear power plant may have already absorbed a dose of 100 millisievert in their thyroid glands, as a result of the radioactive iodine leaked from the plant. In two-year-olds, this increases the risk of developing thyroid cancer by the age of 15 by a factor of five.

In the long term, the radioactive isotope cesium 137 is even more dangerous than radioactive iodine. It has a 30-year half-life and accumulates in the soil and in animals. "Cesium 137 becomes distributed throughout the body and can therefore promote cancer development in various places," says Wolfgang-Ulrich Muller, a radiobiologist in the western German city of Essen.

It can take years or even decades until that happens. Nevertheless, Wolfram König, head of Germany's Federal Office for Radiation Protection, is convinced that the radiation from the Fukushima nuclear power plant has already claimed its first victims -- because of the fear of radiation and not the radiation itself. "It's possible that many of the people who died in the rubble lost their lives because no one dared to help them," says König.

Translated from the German by Christopher Sultan

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