Eric Ripert, the chef of Le Bernardin, the high temple of seafood in Manhattan, bought a new kitchen gadget a few days ago: a radiation detector.

“I just want to make sure whatever we use is safe,” said Ripert, whose staff is using the device to screen every item of food that enters the restaurant, regardless of its origin. He has also stopped buying fish from Japan, which means no high-quality, farm-raised hamachi and kampachi for raw seafood dishes.

“Nobody knows how the currents will carry the contaminated water,” he said.

Despite assurances by health officials that radiation from the stricken Fukushima Dai-ichi nuclear power plant in Japan is unlikely to show up in the food supply, worries about contaminated foods are growing among consumers, businesses and governments worldwide.

On Tuesday, the Japanese government announced new radiation standards for fish after high levels of radioactive iodine and cesium were found in fish caught halfway between the reactor site and Tokyo. In response, the European Union said it would tighten its own radiation limits for Japanese food imports. India said it would ban all food from Japan for at least three months.

In the United States, where about 4 percent of food imports come from Japan, the Food and Drug Administration has restricted some foods from the country. And the agency is working with customs officials to screen incoming fish and other food for traces of radiation.

So far, that screening has identified seven items that required further testing to see if the radiation detected exceeded normal background levels, according to Siobhan Delancey, an FDA spokeswoman. Those items included tea and flavoring compounds. She said three of the items had been cleared for delivery and four were awaiting test results.

Patricia Hansen, a senior scientist at the FDA, acknowledged that the radiation detection methods used to screen food imports were not sensitive enough to detect a single contaminated fish in a large shipment. But she said that small amounts of contamination did not represent a public health hazard. A person would have to consume large amounts of fish in excess of what are known as an “intervention level,” or threshold level, of radiation for an extended period of time before it would be considered dangerous, she said.

“One fish that might be at an intervention level in a huge cargo container, we’re not going to pick that up,” she said. “But the important context is, is that one fish at the intervention level a public health concern? No, it is not.”

Nicholas Fisher, a professor of marine sciences at the State University of New York at Stony Brook, said that, according to some radiation safety guidelines, people could safely eat 35 pounds of fish each year containing the level of cesium 137 detected in the Japanese fish.

“You’re not going to die from eating it right away,” he said, “but we’re getting to levels where I would think twice about eating it.” All the talk about radioactive food in Japan, which earlier banned milk and other farm products from areas near the crippled plant, has made some people uneasy, even thousands of miles away.

“When radioactive material started going into the ocean, that raised my concern greatly,” Karen Werner, 68, said Tuesday as she shopped for fish at 99 Ranch Market in Richmond, Calif. “Right now, I’m not too worried about it showing up in fish, but I’m keeping my eye on it.”

Other food concerns

Other segments of the food industry are also grappling with how to respond to radiation concerns. Sensitive monitoring devices and tests have detected trace amounts of radioactive material from Japan in the air and water in many states. Tests in Arizona, California and Washington state have found minuscule amounts in milk, leading to concern among dairy farmers.

Everything detected has been well below levels considered dangerous, but food companies realize that consumers may still need to be reassured.

In California, Will Daniels, senior vice president for food safety at Earthbound Farm, a major producer of organic salad greens, said the company was prepared to test soil and greens for radiation if concerns persisted or fallout from Japan intensified.

“The likelihood of contamination on the West Coast is extremely low, so it’s really important that we’re monitoring appropriately and not creating panic,” Daniels said. “But we certainly need to make sure we’re doing the appropriate thing and are ready to respond.”

Seaweed boom

Consumer worries about radiation have led to a big boom in sales of one food that often comes from Japan: seaweed.

Natural food stores and Asian markets on the West Coast said they had seen a run on seaweed ever since the nuclear reactors in Japan began leaking radiation. Some consumers view seaweed as a natural source of normal iodine, which can help protect the thyroid gland against exposure to radioactive iodine.

Timothy Zerkel, a manager at Central Co-op in Seattle, said sales of many types of seaweed were far above normal levels and the store’s distributors had begun rationing shipments because they could not keep up with demand.

Scientists cautioned against eating large amounts of seaweed, however, saying that the levels of radioactive iodine reaching this country from Japan were much too low to worry about. And they said that some people could encounter health problems from consuming too much iodine.

In addition, scientists said that radioactive iodine could concentrate at high levels in seaweed. As more contaminated water from the Fukushima reactors enters the sea, health concerns could arise about new seaweed imports from Japan.