BM: Gạo nhập khẩu ở Mỹ bị nhiễm chì

Lúa gạo được trồng trọt ở nhiều nơi trên thế giới.

Gạo nhập khẩu vào Mỹ nhằm phục vụ tiêu dùng được phát hiện là nhiễm chì ở mức độ cao hơn ngưỡng an toàn.

Một số mẫu đưa đi xét nghiệm đã cho kết quả vượt mức nhiễm có thể chấp nhận (PTTI) mà Cơ quan Quản lý An toàn Thực phẩm Hoa Kỳ (FDA) đưa ra.

Bản phúc trình nêu tại Hội nghị Hiệp hội Hóa học Hoa Kỳ nêu vấn đề trên, trong lúc người ta đang đề cập tới việc gạo có chứa chất arsenic

FDA nói với BBC rằng họ sẽ xem xét kết quả nghiên cứu này.

Chì là chất gây hại cho nhiều cơ quan nội tạng và cho hệ thống thần kinh trung ương ở con người.

Chất này đặc biệt gây hại cho trẻ nhỏ.

Các nghiên cứu mới đây cho thấy trong lúa gạo có chất arsenic, khiến cho Cơ quan Quản lý An toàn Thực phẩm của Anh đã ra khuyến cáo tiêu dùng nói không nên cho trẻ nhỏ ở nhóm tuổi đang tập đi trở xuống dùng các sản phẩm thay thế sữa làm từ gạo.

Hoa Kỳ nhập khẩu khoảng 7% tổng lượng gạo tiêu thụ, và nhóm nghiên cứu đã lấy mẫu để xét nghiệm từ các lô hàng nhập từ Bhutan, Italy, Trung Quốc, Đài Loan, Ấn Độ, Israel, Cộng hòa Czech và Thái Lan - là các thị trường cung cấp 65% lượng gạo cho thị trường Mỹ.

Gạo từ Trung Quốc và Đài Loan có mức nhiễm chì cao nhất, tuy người đứng đầu nhóm nghiên cứu nói tất cả các mẫu được xét nghiệm đều có hàm lượng chì cao hơn PTTI.

Imported rice may contain dangerously high lead levels

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 FDA did not respond to a CBSNews.com request for comment at press time.

A spokesperson reportedly told the BBC, that the agency "plans to review the new research on lead levels in imported rice released today" and proactively monitors contaminant levels in foods sold internationally.

RYAN JASLOW