Radioactive materials from the crippled Fukushima No. 1 nuclear plant have been spreading, contaminating milk, vegetables, water and soil in Fukushima and neighboring prefectures.
On Wednesday, 210 becquerels of iodine-131 per liter of water, more than double the government-set safety level of 100 for infants, were detected in water at a purification plant in Tokyo, and 163,000 becquerels of cesium-137 per kg were detected in soil in Fukushima.
Following are questions and answers about the effects of radioactive materials, including iodine-131 and cesium-137, that have been detected in food, water and soil.