December 8, 2011
Arsenic Exposure From Rice
(Ivanhoe Newswire) — Rice is a possible reason for arsenic poisoning in humans, according to this study focusing on the potential for consuming harmful levels of arsenic through various sources.
Arsenic occurs naturally in the environment and in elevated concentrations it can be harmful to human health. Common in groundwater, the World Health Organization set guideline limits for Arsenic levels in drinking water (currently 10 micrograms per liter). Concerns about arsenic exposure are now extending beyond water to rice. Rice is susceptible to arsenic contamination due to its ability to extract arsenic from the environment into the rice plant.
"Arsenic exposure during pregnancy is a public health concern due to potential health risks to the fetus," Margaret Karagas, professor of community and family medicine at Dartmouth Medical School and senior author of the paper, was quoted as saying.
"The study presented in the PNAS paper is based upon a sample of 229 pregnant New Hampshire women whose urine was tested for arsenic concentration," Diane Gilbert-Diamond, a postdoctoral fellow and co-lead author on the paper, was quoted as saying. The women in the study were divided into two groups based on whether or not they had eaten rice in the two days before urine collection. The tap water in their homes also was tested for arsenic concentration.
"This enabled our team to separate the potential for exposure to arsenic from drinking water from that of rice," Gilbert-Diamond said. The urinary arsenic analyses were performed at the University of Arizona by co-author Professor A. Jay Gandolfi and colleagues and water testing was performed at Dartmouth's Trace Element Analysis Facility by co-author Brian Jackson, PhD.
Urinary arsenic concentrations for the 73 study subjects who ate rice showed a median of 5.27 micrograms per liter, while the median for the 156 non-rice eaters showed 3.38 micrograms per liter, a statistically significant difference between the two groups.
The authors conclude that their findings highlight the need to monitor arsenic in food, noting that China already has statutory limits on arsenic content in rice (0.15 micrograms of inorganic arsenic per kilogram of food) but the U.S. and the E.U. do not. Rice concentrations vary widely throughout the world and between species and growing conditions. Karagas emphasizes, "While this study reveals the potential for exposure to arsenic from rice, much additional research is needed before we can determine if there are actual health impacts from this source of exposure." Tracy Punshon, research assistant professor of biological sciences and co-author was quoted as saying, "Rice is a nutritious food source worldwide. Ultimately any health risks, if found, would then need to be weighed against the obvious nutritional benefits of rice consumption."
SOURCE: Proceedings of the National Academy of Sciences, published online December 2011.