TOKYO — The government said Saturday that it had found higher than normal levels of radioactive materials in spinach and milk at farms up to 90 miles away from the ravaged nuclear power plants, the first confirmation by officials that the unfolding nuclear crisis has affected the nation’s food supply.
While officials played down the immediate risks to consumers, the findings further unsettled a nation worried about the long-term effects of the damaged nuclear power plants.
The Tokyo Electric Power Company, with help from the Japan Self-Defense Force, police officers and firefighters, continued efforts to cool the damaged reactors on Saturday to try to stave off a further fuel meltdown and stem the radiation leak. The latest plan involved running a mile-long electrical transmission line to Reactor No. 2 at the Fukushima Daiichi Nuclear Power Station to try to restore power to its cooling system.
About 500 workers from the utility connected the power line on Saturday. They were checking the cooling system, which has been disabled since the earthquake and tsunami hit more than a week ago, and hope to try to restart it on Sunday.
Restoring power at the plant could provide a glimmer of hope after days of increasingly dire news that now includes contaminated food.
Yukio Edano, the chief cabinet secretary, said that spinach and milk were the only products found with abnormally high levels of radioactive materials. The newly discovered radioactivity contained in the average amount of spinach and milk consumed in an entire year would be equal to the amount received in a single CAT scan, he said.
“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 Fukushima Prefecture asked dairy farms within 18 miles of the nuclear plant on Saturday to halt all milk shipments. 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, at farms 60 to 90 miles south of the plants.
Food safety inspectors said the amount of iodine-131 found in the tested milk was five times higher than levels deemed safe. They said the iodine found in the spinach was more than seven times higher. The spinach also contained slightly higher amounts of cesium-137.
Iodine-131 and cesium-137 are two of the more dangerous elements that are feared to have been released from the plants in Fukushima. Iodine-131 can be dangerous to human health, especially if absorbed through milk and milk products, because it can accumulate in the thyroid and cause cancer. Cesium-137 can damage cells and lead to an increased risk of cancer.
Those levels are well beyond what the Food and Drug Administration in the United States considers a cause for concern. But experts say Japan’s reassurances about food safety were probably accurate.
Dr. Harold M. Swartz, a professor of medicine at Dartmouth who studies radiation exposure in people, said that the contamination levels were low and that the government’s advice was “probably reasonable.” But, he added, because people are so afraid of radiation, they are likely to avoid these foods altogether.
That was the case in Tokyo on Saturday, where a handful of vegetable shop owners said they were concerned about the report, but continued to sell vegetables from Fukushima and Ibaraki because they had not been told to stop.
Katsuko Sato, 76, who was shopping for food on Saturday evening, said she would stop buying spinach and, after watching Mr. Edano’s news conference, she called her family and friends to urge them not to, either.
“I’m not going to believe the government because I don’t think only spinach from Ibaraki will be affected,” she said.
Dr. Swartz said people consuming milk and produce, particularly children and pregnant women, should be taking potassium iodide, which saturates the thyroid gland with nonradioactive iodine, and prevents it from taking in the radioactive form. Children and fetuses have the highest risk of thyroid cancer from exposure to radioactive iodine.
The Japanese authorities recommended Wednesday that people in the affected area start taking iodine.