Vast Area Of Japan Contaminated With Radioactivity
eSci: Unsafe Radiation Found Near Tokyo, Vast Area of Japan Contaminated
Japan is dangerously contaminated by radioactivity over a far larger area than previously reported by TEPCO and the central government according to new reports from multiple sources. The prefectural government of Iwate released new data that shows radioactive contamination of grass exceeds safety standards at a distance of 90 to 125 miles from the damaged Fukushima nuclear power plants.
The prefectural government found on Tuesday radioactive cesium exceeding the limit of 300 becquerels per kilogram in grass collected from pastures in four areas, including Tono and Otsuchi. The areas are located about 150 to 200 kilometers north of the Fukushima nuclear power plant.
Science Magazine reports that Japanese scientists have become so concerned about the health of their children that they have initiated their own radiation monitoring program and made their own maps. The results are shocking.
Parents in Tokyo’s Koto Ward enlisted the help of Tomoya Yamauchi, a radiation physicist at Kobe University, to measure radiation in their neighborhood. Local government officials later joined the act, ordering radiation checks of schoolyards and other public places and posting the results on their Web sites. An anonymous volunteer recently plotted the available 6300 data points on a map. And Yukio Hayakawa, a volcanologist at Gunma University, turned that plot into a radiation contour map.
It shows one wide belt of radiation reaching 225 kilometers south from the stricken reactors to Tokyo and another extending to the southwest. Within those belts are localized hot spots, including an oval that encloses northeast Tokyo and Kashiwa and neighboring cities in Chiba Prefecture.
Radiation in this zone is 0.4 microsieverts per hour, or about 3.5 millisieverts per year. That is a fraction of the radiation found throughout much of Fukushima Prefecture, which surrounds the nuclear power plant. But it is still 10 times background levels and even above the 1-millisievert-per-year limit for ordinary citizens set by Japanese law. The health effects of such low doses are not clear and are passionately debated. But it is known that children are more susceptible to radiation than adults, and few parents want to take chances with a child’s health. Besides, “The law should be observed,” Yamauchi says. Kyo Kageura, an information scientist at the University of Tokyo, says there should be a public discussion of the issue, “based on a scrupulous presentation of the data, including to what extent the 1-millisievert limit can be achieved.”