A new federally funded study of more than 200 pregnant women receiving prenatal care in the New Hampshire area reports a link between rice consumption and elevated levels of arsenic in urine, suggesting that “many people in the United States may be exposed to potentially harmful levels of arsenic through rice consumption,” according to the study led by researchers at Dartmouth’s Children’s Environmental Health and Disease Prevention Center.
“The large and statistically significant association we observed between rice consumption and urinary arsenic, in addition to earlier reports of elevated arsenic concentrations in rice, highlights the need to regulate arsenic in food,” advise the authors of the study, which was published in the peer-reviewed journal Proceedings of the National Academy of Sciences.
There are no statutory limits for arsenic in most foods sold in the U.S. and the European Union.
Based on Consumer Reports’ recent investigation, including tests which found elevated levels of arsenic and lead in samples of apple juice and grape juice, Consumers Union, the advocacy arm of Consumer Reports, also has called on the federal government to set legally binding standards in juices of 3 ppb total arsenic and 5 ppb lead, and to take steps that would reduce other dietary exposures to arsenic. Our investigation included an analysis of federal health data that also revealed a link between apple juice consumption and higher levels of total urinary arsenic.
Americans consume an average of a half cup of cooked rice daily, which is more than three times as much rice as they did during the 1930s, the Dartmouth researchers noted. They collected urine samples and three-day dietary records from pregnant women at pre-natal visits and found that each gram of rice consumed was associated with a one percent increase in total urinary arsenic. Their results indicated that consuming slightly more than half a cup of cooked rice per day resulted in a total urinary arsenic concentration comparable to what would be predicted from consuming a liter of water containing the maximum 10 ppb total arsenic limit permissible in public drinking water.
The study’s authors state that arsenic exposure during pregnancy is a particular public health concern. Exposure to this toxin in the womb has been linked to problems ranging from low birth weight and infant mortality to hampered immune function and increased death rates from lung cancer later in life. Arsenic exposure in early childhood also is especially harmful, and since rice-based infant cereals are often the first solid food babies eat, high levels of arsenic in rice are worrisome indeed.
The recent Consumer Reports investigation found that rice is among the foods that tend to have elevated levels of arsenic for two primary reasons. Rice is among the plants that are unusually efficient at taking up arsenic from the soil and incorporating it in the grains people eat. Moreover, much of the rice produced in the U.S. is grown in Arkansas, Louisiana, Mississippi, Missouri, and Texas on land formerly used to grow cotton, where arsenical pesticides were used for decades, just as they were in orchards and vineyards.
When the rice initially planted in some of those former cotton fields produced little grain due to that pesticide residue, farmers solved that problem by breeding a type of rice specifically designed to produce high yields on arsenic-contaminated soil, according to Andrew Meharg, a professor of biogeochemistry at the University of Aberdeen in Scotland. His research has shown that U.S. rice has among the highest average levels in the world of inorganic arsenic, which is known to cause skin, lung and bladder cancer in humans. Rice in the U.S. has also been shown to contain substantial amounts of another organic form of arsenic demonstrated to be carcinogenic in rats.
Rice drinks given to young children who are lactose intolerant may also pose risks. In fact, after a 2008 study conducted by Meharg found levels of inorganic arsenic exceeding 10 ppb in a majority of samples of rice milk tested in the United Kingdom, the UK’s Food Standards Agency advised that children younger than four and half years old should not have rice drinks as a replacement for cows’ milk, breast milk or infant formula.
The Dartmouth researchers conclude that setting regulatory limits in the U.S. for arsenic in food would not only protect consumers from unknowingly purchasing rice or rice products with high levels of arsenic, but would encourage cultivation of rice strains that don’t incorporate as much arsenic and would reduce the use of arsenic-contaminated land for agriculture. Our scientists agree, and to further protect the food supply Consumers Union has urged the federal government to eliminate organic arsenicals in animal feed, ban organic arsenical pesticides, and prohibit the use of arsenic-laden fertilizers.