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TOKYO >>  Radiation leaking from Japan’s tsunami-damaged nuclear power plant has caused Tokyo’s tap water to exceed safety standards for infants to drink, officials said Wednesday, sending anxiety levels soaring over the nation’s food and water supply.

Residents cleared store shelves of bottled water after Tokyo Gov. Shintaro Ishihara said levels of radioactive iodine in tap water were more than twice what is considered safe for babies. Officials begged those in the city to buy only what they needed, saying hoarding could hurt the thousands of people without any water in areas devastated by the March 11 earthquake and tsunami.

"I’ve never seen anything like this," clerk Toru Kikutaka said, surveying the downtown Tokyo supermarket where the entire stock of bottled water sold out almost immediately after the news broke, despite a limit of two, two-liter bottles per customer.

The unsettling new development affecting Japan’s largest city, home to around 13 million people, added to growing fears over the nation’s food supply.

Radiation from the Fukushima Dai-ichi nuclear plant has seeped into raw milk, seawater and 11 kinds of vegetables, including broccoli, cauliflower and turnips, from areas around the plant. The U.S. Food and Drug Administration said it was halting imports of Japanese dairy and produce from the region near the facility. Hong Kong went further and required that Japan perform safety checks on meat, eggs and seafood before accepting those products.

Officials are still struggling to stabilize the nuclear plant, which on Wednesday belched black smoke from Unit 3 and forced the evacuation of workers, further delaying attempts to make needed repairs. The plant, 140 miles north of Tokyo, has been leaking radiation since the quake and tsunami knocked out its crucial cooling systems.

The crisis is emerging as the world’s most expensive natural disaster on record, likely to cost up to $309 billion, according to a new government estimate. Police say an estimated 18,000 people were killed.

Concerns about food safety spread Wednesday to Tokyo after officials said tap water showed elevated radiation levels: 210 becquerels of iodine-131 per liter of water — more than twice the recommended limit of 100 becquerels per liter for infants. Another measurement taken later at a different site showed the level was 190 becquerels per liter. The recommended limit for adults is 300 becquerels.

"It is really scary. It is like a vicious negative spiral from the nuclear disaster," said Etsuko Nomura, a mother of two children ages 2 and 5. "We have contaminated milk and vegetables, and now tap water in Tokyo, and I’m wondering what’s next."

Infants are particularly vulnerable to radioactive iodine, which can cause thyroid cancer, experts say. The limits refer to sustained consumption rates, and officials urged calm, saying parents should stop giving the tap water to babies, but that it was no problem if the infants already had consumed small amounts.

They said the levels posed no immediate health risk for older children or adults.

"Even if you drink this water for one year, it will not affect people’s health," Chief Cabinet Secretary Yukio Edano said.

Dr. Harold Swartz, a professor of radiology and medicine at Dartmouth Medical School in the U.S., said the radiation amounts being reported in the water are too low to pose any real risk, even to infants who are being fed water-based formula or to breast-fed infants whose mothers drink tap water.

Although the amounts are well above established limits, that doesn’t automatically mean there’s a health threat, he said.

"We live in a world that has natural background radiation that’s many times greater than the amounts we’re talking about here," Swartz said.

Still, because it’s easy to avoid tap water, it makes sense for Japanese parents with infants to do so, he said.

Radioactive iodine is also short-lived, with a half-life of eight days — the length of time it takes for half of it to break down harmlessly.

Richard Wakeford, a public health radiologist at the University of Manchester in Britain, blamed the spike in radiation on a shift in winds from the nuclear plant toward Tokyo. He predicted lower levels in coming days once the wind shifts back to normal patterns. "I imagine that bottled water is now quite popular in Tokyo," he said.

Tokyo’s municipal government said it would distribute 240,000 bottles of water to households with infants. They estimated that there are currently 80,000 babies in the affected area, with each infant getting three bottles of 550 milliliters.

Edano pleaded with shoppers to restrict purchases of bottled water to the bare necessity, urging them to think of tsunami victims in need.

"We have to consider Miyagi, where there is no drinking water at all," he said, referring to a stricken region. "Under these conditions, we would appreciate it if people would avoid buying more water than they need."

The latest data showed sharp increases in radioactivity levels in a range of vegetables. In an area about 25 miles northwest of the nuclear plant, levels for one locally grown leafy green called kukitachina measured 82 times the government limit for radioactive cesium and 11 times the limit for iodine.

The death toll from the disaster continued to rise, with more than 9,500 bodies counted and more than 16,000 people listed as missing.

With supplies of fuel and ice dwindling, officials have abandoned the traditional practice of cremation in favor of quick, simple burials. Some are interred in bare plywood caskets and others in blue plastic tarps, with no time to build proper coffins. The bodies will be dug up and cremated once crematoriums catch up with the glut, officials assured families.

In Higashimatsushima in Miyagi prefecture, about 200 miles northeast of Tokyo, soldiers lowered plywood coffins into the ground, saluting each casket.

Some relatives placed flowers on the graves. Most remained stoic, folding hands in prayer. Two young girls wept inconsolably, hugged tightly by their father.

"I hope their spirits will rest in peace here at this temporary place," said mourner Katsuko Oguni, 42.

Masaru Yamagata, a Higashimatsushima official, said the crematorium cannot keep up with demand.

"Giving the grieving families coffins is the most we can do right now," Yamagata said. "Every day, more dead bodies are found, and we need more coffins quickly."

Hundreds of thousands remained homeless, squeezed into temporary shelters without heat, warm food or medicine and no idea what to call home after the colossal wave swallowed up communities along the coast.

The tsunami also heavily damaged the Fukushima Dai-ichi nuclear facility, with explosions and fires in four of the plant’s six reactors sending radioactive steam into the air.

Progress in cooling down the troubled plant has been intermittent, disrupted by rises in radiation, elevated pressure in reactors and overheated storage pools.

The plant’s operator had restored circuitry to bring power to all six units and turned on lights at Unit 3 late Tuesday for the first time since the disaster — a significant step toward restarting the cooling system.

It had hoped to restore power to cooling pumps at the unit within days, but experts warned the work included the risk of sparking fires as electricity is restored through equipment potentially damaged in the tsunami.

And then on Wednesday, black smoke suddenly billowed from Unit 3, prompting another evacuation of workers from the plant in the afternoon, Tokyo Electric Power Co. officials said. They said there had been no corresponding spike in radiation at the plant.

Hidehiko Nishiyama of the Nuclear and Industrial Safety Agency said officials did not know the reason for the smoke.

Tokyo Electric manager Teruaki Kobayashi said the pump for Unit 3 had been tested and was working Wednesday. But officials weren’t sure when they would be able to turn the power on to the pump.

Nuclear agency official Kenji Kawasaki said workers would not be allowed to return to the plant until Thursday morning, since smoke was still rising as of late Wednesday night.

As a precaution, officials have evacuated residents within 12 miles of the plant and advised those up to 19 miles away to stay indoors to minimize exposure.

And for the first time, Edano, the chief Cabinet secretary, suggested that those downwind of the plant should stay indoors with the windows shut tight — even if just outside the zone.

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Associated Press writers Tomoko A. Hosaka, Yuri Kageyama and Jay Alabaster in Tokyo, Tim Sullivan in Higashimatsushima, Mary Clare Jalonick in Washington, Lindsey Tanner in Chicago and Foster Klug in Seoul, South Korea, contributed to this report.