New Jersey researchers say they have discovered potentially dangerous levels of lead in white rice imported to the United States from across the globe.
Dr. Tsanangurayi Tongesayi, an environmental chemistry professor at Monmouth University, said his team's findings are especially concerning for Asian-Americans who eat large amounts of rice, and infants and children who are more sensitive to lead's effects.
"Such findings present a situation that is particularly worrisome given that infants and children are especially vulnerable to the effects of lead poisoning," Tongesayi said in a statement. "For infants and children, the daily exposure levels from eating the rice products analyzed in this study would be 30-60 times higher than the FDA's provisional total tolerable intake (PTTI) levels."
Tongesayi's team analyzed rice samples imported from Asia, Europe and South America. They found the rice contained between 6 to 12 milligrams per kilogram of lead, surpassing the FDA's allowable levels.
The highest amount of lead was found in rice imported from Taiwan and China. Rice from the Czech Republic, Bhutan, Italy, India and Thailand also had significantly high lead levels, the researchers said.
Asians living in the United States tend to consume more rice, Tongesayi pointed out, and their analysis estimated lead exposure in such children can be anywhere between 60 and 120 times higher than the FDA's PTTI levels.
For adults, lead exposure from daily intake of imported rice is about 20 to 40 times higher than the FDA's tolerable levels, the study found.
Tongesayi told TIME the findings may be underestimates, since the team based their calculations on daily recommended servings of rice, when people likely eat more than what's recommended in a given week.
Imported rice makes up about 7 percent of the U.S. supply, the researchers estimated. While the U.S. is a major rice producer, the researchers noted that imports of rice and rice flour have increased by more than 200 percent since 1999. People across the world may be at risk too, given 3 billion people consume rice as a staple in their diets, they added.
The research is ongoing, and considered preliminary since it was presented at a medical conference and not published in a peer-reviewed journal. Tests are currently under way for rice samples from Pakistan, Brazil and other countries.
Even small levels of lead over time can harm a child's mental development, according to the National Institutes of Health. Lead is more harmful to kids than adults because it interacts with the developing nervous system and brain. The younger the child, the more harmful lead exposure can be, the NIH added.
Complications include behavioral problems, IQ deficits, hearing problems, kidney damage and stunted body growth.
This isn't the first chemical of concern that's been found in rice. Several studies, including a September 2012 analysis by Consumer Reports of 200 rice products sold in the U.S., found potentially high levels of inorganic arsenic, which may be toxic and pose a cancer risk.
"If you look through the scientific literature, especially on India and China, they irrigate their crops with raw sewage effluent and untreated industrial effluent," Tongesayi told the BBC.
"Research has been done in those countries, and concerns have been raised because of those practices, but it's still ongoing."
The Food and Drug Administration said in a statement that it is is aware of the new research on lead levels in imported rice.
"FDA reviews the latest food safety research and has systems in place to help ensure that the U.S. food supply is safe," spokesperson Shelley Burgess said in an emailed statement to CBSNews.com.