Rice feeds about half of the world. Flickr/Urijamjari Note: This study finding has been withdrawn after the researchers could not replicate their work.

Commercially available rice imported into the U.S. contains levels of lead far higher than what's considered safe, according to a study by the American Chemical Society and reported by Jason Palmer of the BBC.

The U.S. imports 7 percent of its rice. The team sampled packages from Bhutan, Italy, China, Taiwan, India, Israel, the Czech Republic, and Thailand — accounting for 65 percent of U.S. imports — and found that rice from China and Taiwan had the highest lead levels.

When calculating lead intake, the team factored in how much rice particular demographics consume in a given day.

Levels more than 10 times the "provisional total tolerable intake" (PTTI) set by the U.S. Food and Drug Administration (FDA) are considered concerning to health.

The study found that lead levels for non-Asian adults ranged from 20 to 40 times above the PTTI. For Asian children it was 120 times.

Rice is very susceptible to environmental pollutants in irrigation water, and several rice-producing countries use unsanitary agricultural practices.

"If you look through the scientific literature, especially on India and China, they irrigate their crops with raw sewage effluent and untreated industrial effluent," Lead researcher Dr. Tsanangurayi Tongesayi of Monmouth University told the BBC.

Up to 10 percent of rice grown in China contains heavy metals that probably entered the fertile farmlands in China’s south through industrial waste and sewage disposal.

Lead is harmful to organs and the central nervous system, especially in young children.

Rice products also contain "moderate to moderately high levels of arsenic" (which is also highly toxic), according to a study by Consumer Reports. Palmer notes that Dr. Tongesayi has also worked on quantifying arsenic contamination, and plans on testing the prevalence of other heavy metals.

"With a globalized food market, we eat food from every corner of the world, but pollution conditions are… different from region to region, but we ignore that," Tongesayi said.

The study will be published in the Journal of Environmental Science and Health. The FDA told the BBC that it "plans to review the new research on lead levels in imported rice released today."