This is the VOA Special English Health Report.

This week, Japanese doctors began examining 360,000 children in Fukushima Prefecture. The goal is to learn the extent to which radiation may increase their risk ofthyroid 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. In recent days, 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.

A VOA reporter talked to people at a Little League game on Sunday and found that none of them knew about the radioactive hot spot.

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Two mothers at the ballpark expressed surprise when told about the soil.

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The women say they have 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.

Last week private citizens found abnormal levels of radiation in the air on the path to a Tokyo school. However, government officials say 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 says Japan must avoid becoming too "conservative" in its clean-up efforts.

Japanese officials have ordered an increase in radiation testing, but they say hot spots 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.

And that's the VOA Special English Health Report. I'm Jim Tedder.

thyroid cancer: 甲狀腺癌

tsunami: a very large ocean wave caused by an underwater earthquake or volcanic eruption 海嘯

cesium: a soft, ductile, silvery-white element of the alkali group 銫（55號(hào)元素，符號(hào)Cs）

dosimeter: 放射量測(cè)定器

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（來源：VOA 編輯：Rosy）