FUKUSHIMA, Japan >> Two units at Japan’s stricken nuclear plant safely cooled down Sunday, though pressure unexpectedly rose in a third unit’s reactor and traces of radiation were found in more foods, further shaking an already uneasy public.

The pressure increase meant plant operators may need to deliberately release radioactive steam, prolonging a nuclear crisis that has consumed government attention even as it responded to the catastrophic earthquake and tsunami that savaged northeast Japan on March 11.

In a rare rescue after so many days, a teenage boy’s cries for help led police to rescue him and an 80-year-old woman at a wrecked house.

Beyond the disaster area, uncertainty grew over the safety of food and water. The government halted shipments of spinach from one area and raw milk from another near the nuclear plant after tests found iodine exceeded safety limits. But the contamination spread to spinach in three other prefectures and to more vegetables — canola and chrysanthemum greens. Tokyo’s tap water, where iodine turned up Friday, now has cesium. Rain and dust are tainted too.

In all cases, the government said the radiation levels were too small to pose an immediate risk to health. Still, Taiwan seized a batch of fava beans from Japan found with faint — and legal — amounts of iodine and cesium.

"I’m worried, really worried," said Mayumi Mizutani, a 58-year-old Tokyo resident shopping for bottled water at a supermarket to give her visiting 2-year-old grandchild. "We’re afraid because it’s possible our grandchild could get cancer." Forecasts for rain, she said, were an added worry.

All six of the Fukushima Dai-ichi nuclear complex’s reactor units saw trouble after the disasters knocked out cooling systems. In a small advance, the plant’s operator declared Units 5 and 6 — the least troublesome — under control after their nuclear fuel storage pools cooled to safe levels. Progress was made to reconnect two other units to the electric grid and in pumping seawater to cool another reactor and replenish it and a sixth reactor’s storage pools.

But the buildup in pressure inside the vessel holding Unit 3’s reactor presented some danger, forcing officials to consider venting. The tactic produced explosions of radioactive gas during the early days of the crisis.

"Even if certain things go smoothly there would be twists and turns," Chief Cabinet Secretary Yukio Edano told reporters. "At the moment, we are not so optimistic that there will be a breakthrough."

Nuclear safety officials said one of the options could release a cloud dense with iodine as well as the radioactive elements krypton and xenon.

The plant’s operator, Tokyo Electric Power Co., temporarily suspended the plans Sunday after it said the pressure inside the reactor stopped climbing, though staying at a high level.

"It has stabilized," Tokyo Electric manager Hikaru Kuroda told reporters.

Kuroda, who said temperatures inside the reactor reached 572 degrees Fahrenheit, said the option to release the highly radioactive gas inside is still under consideration if pressure rises.

Growing concerns about radiation add to the overwhelming chain of disasters Japan has struggled with since the 9.0-magnitude quake. The quake spawned a tsunami that ravaged the northeastern coast, killing more than 8,100 people, leaving 12,000 people missing, and displacing another 452,000, who are living in shelters.

Fuel, food and water remain scarce. The government in recent days acknowledged being caught ill-prepared by an enormous disaster that the prime minister has called the worst crisis since World War II.

The official death toll rose to 8,450, with more than 12,900 reported missing. Bodies are piling up in some of devastated communities and badly decomposing even amid chilly rain and snow.

"The recent bodies — we can’t show them to the families. The faces have been purple, which means they are starting to decompose," says Shuji Horaguchi, a disaster relief official setting up a center to process bodies in Natori, on the outskirts of Sendai. "Some we’re finding now have been in the water for a long time, they’re not in good shape. Crabs and fish have eaten parts."

Before the disasters, safety drills were seldom if ever practiced and information about radiation exposure rarely given in Futuba, a small town in the shadow of the nuclear plant, according to 29-year-old Tsugumi Hasegawa. In the aftermath, she is living in a shelter with her 4-year-old daughter and feeling bewildered.

"I still have no idea what the numbers they are giving about radiation levels mean. It’s all so confusing. And I wonder if they aren’t playing down the dangers to keep us from panicking. I don’t know who to trust," said Hasegawa, crammed with 1,400 people into a gymnasium on the outskirts of Fukushima city, 50 miles away from the plant.

Another nuclear safety official acknowledged Sunday that the government only belatedly realized the need to give potassium iodide to those living within 12 miles of the nuclear complex.

The pills help reduce chances of thyroid cancer, one of the diseases that may develop from radiation exposure, by preventing the body from absorbing radioactive iodine. The official, Kazuma Yokota, said the explosion that occurred while venting the plant’s Unit 3 reactor last Sunday should have triggered the distribution. But the order came only three days later.

"We should have made this decision and announced it sooner," Yokota told reporters at the emergency command center in the city of Fukushima. "It is true that we had not foreseen a disaster of these proportions. We had not practiced or trained for something this bad. We must admit that we were not fully prepared."

The higher reactor pressure may have been caused by a tactic meant to reduce temperatures — the pumping of seawater into the vessel, said Kuroda, the Tokyo Electric manager.

Using seawater to cool the reactors and storage ponds was a desperate measure adopted early this past week; Unit 4’s pool was sprayed again Sunday and a system to inject water into Unit 2’s reactor was repaired. Experts have said for days that seawater would inevitably corrode and ruin the reactors and other finely milled machine parts, effectively turning the plant into scrap.

Edano, the government spokesman, recognized the inevitable Sunday: "It is obviously clear that Fukushima Dai-ichi in no way will be in a condition to be restarted."

Contamination of food and water compounds the government’s difficulties, heightening the broader public’s sense of dread about safety. Consumers in markets snapped up bottled water, shunned spinach from Ibaraki — the prefecture where the tainted spinach was found — and overall expressed concern about food safety.

Experts have said the amounts of iodine detected in milk, spinach and water pose no discernible risks to public health unless consumed in enormous quantities over a long time. Iodine breaks down quickly, after eight days, minimizing its harmfulness, unlike other radioactive isotopes such as cesium-137 or uranium-238, which remain in the environment for decades or longer.

Rain forecast for the Fukushima area also could further localize the contamination, bringing the radiation to the ground closer to the plant.

Edano, the government spokesman, tried to reassure the public for a second day running Sunday. "If you eat it once, or twice or even for several days, it’s not just that it’s not an immediate threat to health, it’s that even in the future it is not a risk," Edano said. "Experts say there is no threat to human health."

No contamination has been reported in Japan’s main food export — seafood — worth about $1.6 billion a year and less than 0.3 percent of its total exports.