As workers struggle with damaged Fukushima nuclear plant in Japan, the potential risk of more radiation will be released remains unknown. But the events unfolding since Friday earthquake gave those responsible for public health time to plan ahead, contrary to what happened after 1986 Chernobyl accident. And that means they can reduce human exposure to radiation, said a scientist who has studied the disaster.
The effect of the most significant health Chernobyl was a sharp increase in children with thyroid cancer - more than 6,000 cases, according to a recent UN report. To reduce the chances of such an increase, people living near the plant were being given potassium iodide tablets. The idea is to flood the thyroid with iodine and block inhaled radioactive iodine-131 or ingested into the thyroid. But "the time is critical," said Fred Mettler, emeritus professor of radiology at the University of New Mexico, who led an international team that investigated the health effects of the accident. If taken 1 day before exposure, pills are 80% effective, he said, if taken during the exposure point 100% effective; 8:00 later, 30% (except for pregnant women there. not many reasons adults over 20 to take the tablets, Mettler adds, because their risk of cancer is low.)
in Chernobyl, iodine-131 was also obtained in food supply through the milk of cows that had fed in pastures contaminated with radioactive iodine. Japan can prevent this by banning cows grazing in contaminated pastures, he said, or storing dairy or cheese for 80 days until the radioactivity disappeared.
Another risk is cesium-137, which can also be spewed into the air from a nuclear power plant. Its half-life is 30 years. In Chernobyl, he entered the food chain through the soil and eventually into the meat, berries and mushrooms. One solution is to dig half a meter or more above the ground, said Mettler. But the isotope also leaves the body within 2 months, so another option is to feed the livestock own food for a few months before slaughter, says Mettler. (People who accidentally ingest radioactive cesium are sometimes given a chemical called Prussian blue, which binds to cesium and helps the body to excrete. But by taking pills for cuts exposure weeks only 50%, and levels Japan will probably be too low to justify such action, said Mettler.)
Japan is also to minimize the exposure of people evacuating the area 20 km around the plant and advise people less than 10 kilometers outside of the area to stay indoors. These measures will reduce their exposure to both gamma rays (which are attenuated by walls) and radioactive particles in the air.
The bottom line, Mettler said, is that the radiation levels measured by monitors that do not correspond with what actually between people's bodies. "The trick is to keep people from being exposed."
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