Scientists from China, Italy, and the University of Bayreuth in Germany have become the first to study how sulfur-containing arsenic compounds, called thioarsenates, form in rice-growing soil. Until now, nobody has ever evaluated the possible negative health effects of exposure to thioarsenates through rice consumption.
Dr. Britta Planer-Friedrich, a professor of environmental geochemistry and the lead researcher on the team, developed a method to accurately detect thioarsenates in rice soil. Previous detection methods couldn’t distinguish sulfur-containing arsenic compounds from oxygen-containing arsenic compounds.
As Planer-Friedrich explains, “The uptake of the various thioarsenates in rice plants and the potential risks to human health arising from them urgently require further research. Rice is the world's most important foodstuff and secures the basis of life for more than one half of the world's population and calls for legally defined limits to be set for all toxic arsenic compounds in future.”
In both China and Italy, the team found that sulfur-containing arsenic compounds form over time in rice fields, and the level of thioarsenates in the soil directly influences the pH of the soil. According to Jiajia Wang, a Bayreuth Ph.D. student and first author of the study, "These findings contain valuable starting points for the development of forecasting methods. If in future we could predict, without great technical effort, on which rice fields particularly large or only small amounts of sulfur-containing arsenic compounds are to be expected, it would be an important contribution to the assessment of health risks."