The effect of normal treatment methods at home in the removal of heavy metals from surface of rice distributed in Riyadh region

Abstract

Cleaning of rice with water with or without prior soaking may decrease the levels of heavy metals. The current study evaluated the efficacy of ordinary treatment techniques such as water washing in expelling the heavy metals found on the rice grains. Three varieties of rice were chosen: Abu Kass and Al Walimah from Riyadh area. Assessments were performed by Scanning Electron Microscopy (SEM). The two most common treatment techniques were washing a few times or after soaking for two hours. Diverse rates of heavy metals were present on the surface of rice grains of various types. A total of 15 different types of metals were found on the surface of samples with Zn, Cu, and Pb being present in all varieties of rice. Washing several times and soaking for two hours was effective in removing heavy metals from rice. However, important elements like Zn (15.9%), Mg (23.82%), K (22.05%) and Ca (16.75%) were lost to water after washing for several times. Interestingly, the concentrations of Hg and Pb were found to be high in Abu Kass rice (Hg: 19.7%; Pb: 13.4%); this can raise serious health concerns warranting further investigations. The presence of Pt in Abu Kass rice without washing (54.5%) and after washing several times (73.7%) is also a cause of concern. The results demonstrated the effectiveness of washing for several times and soaking for two hours to help in total dilution or removal of the elements. Soaking followed by washing may be more effective in removing more elements.