Shoppers look at empty shelves at a supermarket after salt sold out in Beijing on March 17, 2011. LIU JIN / AFP / Getty Images

In the misinformed belief that the iodine in table salt might help them escape the effects of radiation from Japan’s crippled nuclear plant, anxious shoppers across China are rushing to snap up the seasoning.

(More on TIME.com: See how to help earthquake and tsunami victims in Japan.)

As the nuclear crisis at northeastern Japan’s Fukushima Daiichi plant unfolds, and despite Beijing’s repeated assurances that they are not imminently at risk, China’s denizens have grown increasingly panicked. The latest round of rapidly circulating rumors has radiation-fearing residents turning to sodium.

Mainland markets, and even small independent grocers, report that they are presently swarming with anxious customers under the impression that iodized salt is capable of defending against radioactivity. (In China, the mineral is iodized in keeping with a national policy that aims to prevent iodine deficiency.) Others are convinced that after today, all incoming sea salt will have been exposed. The current widespread, frenzied buying of the seasoning, which is normally cheap and plentiful, has emptied retail stores of the product and jacked up prices.

“Salt sold out early this morning,” an unnamed employee of the French grocery chain Carrefour in Shanghai told the AFP. According to the worker, the shop’s store of salt was depleted within a half hour of opening time Thursday. She also said that other sellers around town had raised salt prices by up to 600%.

Another supermarket in the south Chinese city of Guangzhou, 75 miles from Hong Kong, has imposed limits on the amount of salt consumers can purchase in the face of unrelenting queues. “One client can only buy two bags of salt,” a staff member told the AFP. Zou Hemei, a woman in Shanghai, went to six supermarkets to try and get salt to cook with, but found all of their supplies exhausted. “I ended up buying soy sauce as a substitute,” she said to Bloomberg. A customer in the seaport city of Ningbo told CCTV that she brought home a five-year supply of the granule to allay her family’s fears.

(More on TIME.com: Is Japan’s nuclear disaster out of control?)

The U.S. Centers for Disease Control confirms that potassium iodide pills keep the thyroid from absorbing radioactive iodine. But experts have been adamant that the iodine content of edible salt—20 to 30 microgrammes per kilogramme, China National Radio has reported—is much too low to have any impact on radiation contamination. Dr. Richard Cyr of Beijing’s International Medical Center blogs that in order to benefit from the equivalent of the 130mg of potassium iodide recommended for adults during a radiation disaster, one would have to ingest 250 tablespoons of iodized salt a day.

The heightened demand for table salt may be unwarranted, but state distributors are working to meet it nonetheless. The country’s largest salt producer, China National Salt Industry Corp., has reassured the public that it has ample reserves. “Panic buying and hoarding is unnecessary,” the company said in a statement to government-run news agency Xinhua, adding that it has launched an emergency response program to accelerate production and distribute the product around the clock. China Salt reportedly sold 4,000 tons of salt on Thursday in the eastern coastal province of Zhejiang alone, eight times as much as usual. Scare buying has also sent the shares of salt makers soaring.

In an effort to calm the nation, the Ministry of Environmental Protection has announced that radiation levels in 41 cities across China are entirely normal. The heart failure that could accompany taking excessive amounts of iodine unsupervised is now a much more immediate risk than radiation contamination in the country, which is thousands of miles from the scene of the Japanese catastrophe. (via AFP)

(More on TIME.com: See TIME’s complete coverage of the crises in Japan.)