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Tuesday, Nov. 8, 2011
Fukushima health concerns
As efforts to end the nuclear disaster at Tokyo Electric Power Co.'s Fukushima No. 1 nuclear power plant drag on, it is important for the central and local governments to step up their efforts to closely examine the health conditions of people concerned and to decontaminate areas contaminated by radiation.
The people who have been most affected by radiation from the Fukushima plant are workers, both from Tepco and from subcontractors, who have been trying to bring the radiation-leaking plant under control. In the nation's history, these workers rank second only to the victims of the atomic bombings of Hiroshima and Nagasaki in terms of their exposure to radiation, therefore the possibility cannot be ruled out that they will develop cancer. Tepco and the central government must do their best to prevent workers' overexposure to radiation and take necessary measures should workers become overexposed to radiation.
It is of great concern that little has been disclosed regarding the conditions of the workers at the Fukushima No. 1 nuclear power plant. Tepco and the central government should disseminate information on the actual working conditions of these people, even if such information seems repetitious and includes what they regard as minor incidents. People are forgetful. They need to be informed. Such information will help raise people's awareness about the issue of radiation and its impact on health.
It must not be forgotten that exposure to radiation has long-term effects on human health. In the Hiroshima and Nagasaki atomic bombings, the number of leukemia cases started to increase among bombing survivors two years after the bombs were dropped. In the case of the 1986 Chernobyl accident, thyroid cancer began to appear among children several years after the disaster happened. Particular attention should be paid to the health of children.
In view of these facts, it is logical that the Fukushima prefectural government has developed a program to monitor the health of all residents in the prefecture, who number about 2 million, throughout their lifetime. It has also started examining the thyroids of some 360,000 children who are age 18 or younger. Detailed and long-term area-by-area studies should be carried out to record cancer incidences.
In August, the Nuclear Safety Commission of Japan estimated that the Fukushima accidents released a total of 570,000 terabecquerels of radioactive substances, including some 11,000 terabecquerels of radioactive cesium 137.
But a preliminary report issued in late October, whose chief writer is Mr. Andreas Stohl of the Norwegian Institute for Air Research, estimates that the accidents released about 36,000 terabecquerels of radioactive cesium 137 from their start through April 20. It is more than three times the estimate by Japan's Nuclear Safety Commission and 42 percent of the estimated release from Chernobyl.
On the basis of measurements by a worldwide network of sensors, the report says that 19 percent of the released cesium 137 fell on land in Japan while most of the rest fell into the Pacific Ocean. It holds the view that a large amount of radioactive substances was released from the spent nuclear fuel pool of the No. 4 reactor, pointing out that the amount of radioactive emissions dropped suddenly when workers started spraying water on the pool.
The report reinforces the advice that local residents in Fukushima Prefecture should try to remember and document in detail their actions for the first two weeks of the nuclear disaster. This will be helpful in estimating the level of their exposure to radiation. But it must be remembered that sensitivity to radiation differs from person to person. It may be helpful for individuals to carry radiation dosimeters to measure their exposure to radioactive substances.
As for internal radiation exposure from food and drink, the Food Safety Commission on Oct. 27 said that a cumulative dose of 100 millisieverts or more in one's lifetime can cause health risks. But when it had mentioned the limit of 100 millisieverts in July, it explained that the limit covered both external and internal radiation exposure. Its new announcement means that the government has not set the limit for external radiation exposure. It also failed to clarify whether the new dose limit is safe enough for children and pregnant women.
The day after the commission's announcement, health minister Yoko Komiyama said the government will lower the allowable amount of radiation in food from the current 5 millisieverts per year to 1 millisieverts per year. The new standard will be applied to food products shipped in and after April 2012. The government will set the amount of allowable radioactive substances for each food item. The health ministry estimates that at present, internal radiation exposure among various age groups from food in the wake of the Fukushima No. 1 accidents is about 0.1 millisieverts per year on the average and that if the new standard is enforced, the lifetime radiation dose will not exceed 100 millisieverts.
It is important for the central and local governments to establish a system to closely measure both outdoor radiation levels and radiation levels in food products and to take necessary measures. In areas near Fukushima No. 1 power plant, many hospitals' functions have weakened because doctors and nurses have left. Urgent efforts must be made to beef up medical staffing at these hospitals.