TOKYO — The government said on Saturday that they had found levels of radioactive materials above safe limits in spinach and milk in Fukushima and Ibaraki prefectures, the first confirmation by officials that the nuclear catastrophe unfolding at power plants nearby has affected the nation’s food supply.
Yukio Edano, the chief cabinet secretary, said that the radioactivity contained in the average amount of spinach and milk consumed during an entire year would be equal to the amount received in a single CAT scan. Mr. Edano said that abnormal amounts of radioactivity were found only in these two products, though other foods were tested.
It was not known how much affected milk and spinach had already been shipped.
Asparagus, cucumbers, radish, tomatoes and other vegetables are also grown in the region.
The government has not banned shipments of milk or spinach from the affected areas, but it would further study the issue, Mr. Edano said. The milk that contained higher levels of radioactive material was tested at farms about 19 miles from the hobbled nuclear plants in Fukushima Prefecture. The spinach was found in Ibaraki Prefecture farther south.
“These levels do not pose an immediate threat to your health,” Mr. Edano said, adding that the Health, Labor and Welfare Ministry would provide additional details. “Please stay calm.”
The findings are likely to alarm an already skittish nation worried about the long-term effects of the damaged nuclear power plants, which have become an international safety concern. The damage to the reactors has reduced the electricity supply in the greater Tokyo region, leading to rolling blackouts.
Residents in neighboring Asian countries are already on edge about the possibility of fallout from the nuclear plants reaching their shores. Japan, however, exports relatively little of its produce.
The government is rushing to find a way to cool the damaged reactors at the Fukushima Daiichi Nuclear Power Station to prevent a full-scale meltdown. In a separate news conference, Defense Minister Toshimi Kitazawa said that temperatures outside the four hobbled nuclear reactors in Fukushima were lower than expected, but he was unable to confirm how hot it was inside the damaged buildings, leaving open the possibility that nuclear fuel may still be overheating.
Temperatures were below 212 degrees Fahrenheit based on readings taken by firefighters from the Japan Self-Defense Force that drove trucks with water cannons to within about 60 feet of the No. 3 reactor on Friday.
Mr. Kitazawa said that the temperature readings had increased hopes that the nuclear fuel could be kept cool through further efforts to spray the reactors with water, while technicians worked on restoring power to the cooling systems.
“What we are ultimately working toward is getting to a point where water is continuously pouring into the reactors,” he said, adding that engineers were also working to find a way to assess water levels inside the reactors, which were currently unapproachable by workers because of high levels of radiation.
Late Friday, Tokyo Electric Power Company finished running a high-power transmission line about a mile meters to buildings that house the damaged reactors. About 500 workers from the company were trying on Saturday to use the power line to restart the systems used to cool the reactors.
The National Police Agency said on Saturday that there were nearly 7,200 confirmed deaths so far, and nearly 11,000 people remained missing. Authorities have said they expect the final death toll to exceed 10,000.