 This is the VOA Special English Health Report. Japanese doctors have begun examining 360,000 children in Fukushima prefecture. The goal is to learn the extent to which radiation may increase their risk of thyroid cancer. Children who lived closest to the Fukushima-1 nuclear power station were among the first to be tested. The earthquake and tsunami that struck northeastern Japan in March left 20,000 people dead or missing. So far, no one has died from radiation exposure. But tens of thousands remain displaced from a 20-kilometer area around the disabled power plant. Officials say the thyroid tests will be done every two years until the children reach the age of 20. After that, tests will be done every five years. Most cancers of the thyroid gland can be treated if found early. Some people in Tokyo and other cities are measuring radiation levels themselves. They worry about a possible risk from Fukushima. Recently, a private laboratory confirmed the presence of increased levels of radioactive cesium in some dirt at Tokyo's Edogawa ballpark. The area is nearly 250 kilometers from the reactors. Two mothers at the ballpark expressed surprise when told about the radioactive hotspot. The women said they had heard many general reports about radiation since the disaster in March. They felt they could not be overly concerned about those reports or they would not be able to go on with their daily lives. Private citizens found abnormal levels of radiation in the air on the path to a Tokyo school. However, government officials said the cause was under the floor of a nearby house, old bottles containing radium powder. Radium was used in the past to make watch and clock faces glow in the dark. The International Atomic Energy Agency said in October that Japan must avoid becoming too conservative in its cleanup efforts. Japanese officials have ordered an increase in radiation testing, but they say hotspots outside Fukushima are not a cause for worry. They say no one spends enough time at the sites to get enough radiation to cause harm. They also say the small dosimeters that some private citizens use to measure radiation can give a wrong reading. For VOA Special English, I'm Alex Villareal. Our programs are a way for people to read, listen, and learn American English and much more. You can download transcripts and MP3s of our stories at voaspecialenglish.com.