An assessment on toxic and essential elements in rice consumed in Colombo, Sri Lanka

Being the dietary staple in most Asian countries, the concentrations of toxic and essential element content in rice is an important aspect in terms of both toxicological and nutritional standpoints. This study aimed to analyse trace elements (As, Cd, Pb, Hg, Cr, Ni, Zn, Cu, Mn, Fe, and Mo) in improved, traditional, and imported rice varieties consumed in Colombo district, Sri Lanka during 2018 and 2019. Further, the potential health risks were assessed in terms of maximum levels and provisional tolerable daily intake. Among the toxic elements analysed, As, Cd, Cr, and Pb were detected in certain rice varieties. Arsenic was detected in all three rice categories and the number of As detected samples were higher compared to other toxic elements in 2018 and 2019. In 2018, 4.2% of traditional rice exceeded As maximum level (0.2 mg/kg) whereas 2.1% of improved and 4.2% of traditional rice exceeded Pb maximum level (0.2 mg/kg). However, none of the toxic elements in rice exceeded the respective maximum levels in 2019. Only mean estimated daily intake of Pb through Kaluheenati exceeded the provisional tolerable daily intake value (0.0015 mg/kg bw/d) in 2018. Rice varieties that reported the highest toxic elements were Basmathi (imported), Samba (improved), and Kaluheenati, Madathawalu, Pachchaperuman, and Suwadel (traditional). With regard to essential elements, concentrations of Fe, Zn, Cu, Mn, and Mo in rice were positively correlated (p < 0.05) to each other, and the highest essential element concentration were found in traditional rice with red pericarp (i.e., Kaluheenati, Madathawalu, and Pachchaperuman).