2011 Tōhoku earthquake and tsunami
It was reported that radioactive iodine was detected in the tap water in Fukushima, Tochigi, Gunma, Tokyo, Chiba, Saitama, and Niigata, and radioactive caesium in the tap water in Fukushima, Tochigi and Gunma. Radioactive caesium, iodine, and strontium were also detected in the soil in some places in Fukushima. There may be a need to replace the contaminated soil. Many radioactive hotspots were found outside the evacuation zone, including Tokyo. Food products were also found contaminated by radioactive matter in several places in Japan. On 5 April 2011, the government of the Ibaraki Prefecture banned the fishing of sand lance after discovering that this species was contaminated by radioactive caesium above legal limits. As late as July 2013 slightly elevated levels of radioactivity were found in beef on sale at Tokyo markets.
Environmental impact of nuclear power
Nuclear power reactor accidents can result in a variety of radioisotopes being released into the environment. The health impact of each radioisotope depends on a variety of factors. Iodine-131 is potentially an important source of morbidity in accidental discharges because of its prevalence and because it settles on the ground. When iodine-131 is released, it can be inhaled or consumed after it enters the food chain, primarily through contaminated fruits, vegetables, milk, and groundwater. Iodine-131 in the body rapidly accumulates in the thyroid gland, becoming a source of beta radiation.