Recent research has concluded that 10 percent of the rice sold in national markets is likely to be tainted with heavy metals, but agricultural experts said the pollution is confined to particular regions and there is no call for panic.

The report comes from the Nanjing Agricultural University's Institute of Resource, Ecosystem and Environment of Agriculture.

After taking samples of 91 kinds of rice collected from markets in six agricultural regions in China in 2007, researchers found 10 percent of the rice samples was laced with cadmium - a heavy metal that is associated with high blood pressure, bone fractures and pain if high concentrations of it accumulate in a person's body, according to a report in Century Weekly magazine's Feb 14 issue.

The research team, led by Professor Pan Genxing, sallied forth again in 2008, this time concentrating on the country's southern region. It found that over 60 percent of the rice samples it took were tainted with cadmium. In some samples, the cadmium level was equal to five times of the legal maximum.

The findings were first published in an environmental magazine, but received little notice until the Century Weekly magazine shined a spotlight on them this week.

China, which produces and consumes more rice than any other country, grows nearly 200 million tons of rice a year. If 10 percent of that total is contaminated with cadmium, then roughly 20 million tons may be tainted, according to the report.

Pan and other experts said the pollution is confined to a few specific regions, so there is no reason for a general panic.

Shang Qi, a researcher from Chinese Center for Disease Control and Prevention, said: "Cadmium tainting is prevalent in the Guangxi Zhuang autonomous region, Guizhou and Hunan provinces, but not other parts of the country."

"So it would be hasty to conclude that 10 percent of the rice sold on the market is contaminated with cadmium," he said. "The original findings only said that it was 10 percent of the samples collected that were tainted."

Shang is taking part in a nationwide study of the pollution and ailments caused by heavy metals. The work was commissioned by the Ministry of Health and the Ministry of Environmental Protection and is expected to be published next year.

Pan said he believes rice pollution is more common in the south because "the soils there are acidic".

"Much of the cadmium comes from the chemical waste of local blast furnaces, and rice absorbs more cadmium than any other crop," said Pan.

He said city residents should not overconcern themselves with rice's ability to take in cadmium, because the grain sold in big cities usually comes from a diverse array of regions and farmlands, thus lowering the risk of "being poisoned".

"The real victims are the farmers who live in or around these polluted areas," he added. "All of what they eat comes from the field. So cadmium is very likely to accumulate in their bodies, and endanger their health."

The scandal has stirred little reaction among consumers. Both high-end supermarkets and neighborhood grocery stores interviewed by China Daily on Tuesday said that their rice sales had neither risen nor dropped since the research results were disclosed.

"Most of my rice comes from the suburbs or Northeast China," said Wang Fugen, a rice dealer in Shanghai.

Chen Huili, a 50-year-old housewife in Shanghai, says that she has become slightly "immune" to widespread concerns over food safety and somehow "wishes (the scares) could help reduce the price of rice a bit", especially as the country is seeing a rise in inflation.

"There is nothing we can do as consumers," she said. "From milk, drainage oil (used cooking oil recycled from restaurant waste), to tainted pork, it seems that once every several months, there is a type of food that is going wrong. But our life has to go on, and we can't eliminate all of it from our table, especially since a lot of the foods are staples in our diet."

According to a nationwide survey conducted by Tsinghua University and Qiushi magazine, 70 percent of 1,010 respondents interviewed felt "insecure" about Chinese food safety.

Shang Qi with the Chinese Center for Disease Control and Prevention said that China lacks a good way to measure the health risks that arise from pollution.