This is the VOA Special English Health Report.

This week, Japanese doctors began examining three hundred sixty thousand 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 twenty thousand people dead or missing. So far no one has died from radiation exposure. But tens of thousands remain displaced from a twenty-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 twenty. 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.