Rice imported from some countries contains high levels of lead that could pose a health risk to children, researchers have claimed.
US experts detected concentrations of lead ranging from six to 12 milligrams per kilogram in rice from several sources.
The highest amounts were seen in rice originating from China and Taiwan. Significantly high levels were also found in samples from the Czech Republic, Bhutan, Italy, India and Thailand.
Infants and children consuming the rice would be exposed to lead levels 30 to 60 times higher than the tolerable safety limits set by the US Food and Drug Administration (FDA), said the study authors.
For Asian children, who consume more rice, exposures could be up to 120 times higher. For adults, daily exposure levels were 20 to 40 times higher than the FDA guidelines.
"Such findings present a situation that is particularly worrisome given that infants and children are especially vulnerable to the effects of lead poisoning," said study leader Dr Tsanangurayi Tongesayi, from Monmouth University in New Jersey.
The findings were presented today at the annual meeting of the American Chemical Society in New Orleans.
The researchers are still in the process of analysing rice samples from Pakistan, Brazil and other countries.
Lead accumulates slowly in the body, and can lead to nerve and kidney damage, as well as anaemia.
One study has shown brain shrinkage in workers exposed to lead through their occupations.
Long-term lead exposure has been linked to reduced IQ and disruptive behaviour in children.
Rice is the staple food of around three billion people worldwide.
In the UK, the average person consumes around 5.6 kilograms of rice per year. Consumption in the UK is expected to increase as the ethnic population expands and food tastes diversify.
Rice imports account for only about 7% of the rice consumed in the US, which is a major producer and exporter of the grain.