Health inspectors are still trying to determine whether any spinach had been shipped from the six farms in Ibaraki Prefecture where the contaminated produce was found, according to Taku Ohara, an official in the food safety division of the Health, Labor and Welfare Ministry. No contaminated milk had been shipped from the three farms where higher than normal radioactive levels had been detected.
Mr. Ohara said that Japan is particularly strict in determining what constitutes safe radioactive levels. It is also fastidious in inspecting food imported from China and other countries. Leafy spinach is especially susceptible to absorbing radioactive material, Mr. Ohara said.
Asparagus, cucumbers, radish, tomatoes and other vegetables are also grown in Fukushima, but have not been found to be contaminated. However, only a small number of farms have been tested because officials have been overwhelmed in the wake of the earthquake, tsunami and the nuclear crisis that followed, Mr. Ohara said.
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.
Though land-poor Japan imports much of the fruit, grain and soybeans that it consumes, 79 percent of the vegetables eaten here are grown domestically. Japan is the largest net importer of food in the world.
A handful of vegetable shop owners in Tokyo interviewed on Saturday said they were concerned about the impact of the nuclear crisis on their supplies, but they continued to sell vegetables from Fukushima and Ibaraki because they have not been told otherwise.
However, the news of the contamination had an immediate impact on consumers. Katsuko Sato, 76, 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.
“Everything that we are going through now is a lot scarier than the bombing attacks during World War II,” she said. “I’m not going to believe the government because I don’t think only spinach from Ibaraki will be affected.”
There have been no reports of contaminated fish or meat.
Many of the ports, fleets and processing facilities in Tohoku, the area most affected by the tsunami and nuclear crisis, were so badly damaged that no fish or seafood has reached Tsukiji market in central Tokyo, according to the market’s general manager, Tsutomo Kosaka. The market handles 90 percent of the seafood for about 40 million consumers in the greater Tokyo area.
Japan’s leading producers of premium beef, including the world-famous Kobe brand, said Saturday that they had not yet tested their cattle or feed. But they were nervous about the possible spread of radiation from Fukushima.
“Even though the government hasn’t mentioned the possibility of contamination of beef, we should start testing to convince people the beef is safe,” said Hiroshi Uchida, a former professor of agriculture who is director of the national cattle museum in Iwate Prefecture, about 150 miles north of the damaged reactors in Fukushima. “We need scientific proof and hard data to protect the beef brand.”
While only spinach and milk were found to have radioactive materials above established limits, some countries have been testing food imports from Japan since the day after the quake and tsunami. In Hong Kong, for instance, 216 Japanese products passed food-quality screenings, including meat, fish, fruits and vegetables.
In Japan, the damage to the reactors has reduced the electricity supply in the greater Tokyo region, leading to rolling blackouts that have slowed business activity.
The government is rushing to find a way to cool the damaged reactors in Fukushima to prevent a full-scale meltdown. In a news conference on Saturday, 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 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.
The National Police Agency said on Saturday that there were nearly 7,200 confirmed deaths so far because of the earthquake and tsunami last week, and nearly 11,000 people remained missing. Authorities have said they expect the final death toll to exceed 10,000.