Detection of metals and trace elements in rice in Matlab, Bangladesh: A descriptive study

Abstract: Rice is the staple food for almost half of the global population, including Bangladesh. This may be problematic, as rice may be contaminated with toxic metals, like arsenic (As), cadmium (Cd), lead (Pb) due to industrialization, overuse of cultivating land, fertilizers and pesticides. The aim of the present project was to assess concentrations of these metals and some essential elements such as selenium (Se), manganese (Mn), iron (Fe) in rice samples from Matlab, a rural area in Bangladesh with prevalent arsenic contamination. In total, 480 rice samples were collected at the 15-year follow-up of the longitudinal MINIMat study in Matlab, and elements were measured using inductively coupled plasma mass spectrometry (ICPMS). The mean ± SD concentrations of As, Cd, Pb, Mn, Fe, Se were 166±115 µg/kg, 103±91 µg/kg, 14±53 µg/kg, 6.6±4.0 mg/kg, 9.0±9.0 mg/kg, 52±23 µg/kg per dry weight, respectively. As, Pb, Mn and Fe were higher in unpolished long rice grains than in polished round rice, while Cd and Se were higher in partially polished round rice. Expectedly, locally grown rice contained higher concentrations of all elements, except Cd, compared to rice from the market. Estimation of the dietary metal exposure indicated that in many individuals exceeded the tolerable weekly intake (TWI) of Cd and Pb, and the adequate daily intake (AI) of Mn, which may result in adverse health outcomes. Further large-scale studies of metal concentrations in soil, irrigation water, and various rice species are needed to highlight sources and future mitigation process to ensure safe food practice.