Contamination of rice crop with potentially toxic elements and associated human health risks-a review

Production of rice, a major staple food crop, should be maintained both quantitatively and qualitatively to assure global food security. In recent decades, various natural (biogeochemical weathering of rocks) and anthropogenic (increased application of agrochemicals, solid and liquid waste discharges from domestic and industrial areas, vehicular pollution, etc.) activities have deteriorated soil and water resources by contributing potentially toxic elements (PTEs) to the environment. Shortage of land resources and requirements of the ever-increasing human population has led to increasing global trend of rice cultivation in contaminated soils, causing accumulation of various PTEs such as arsenic (As), mercury (Hg), cobalt (Co), cadmium (Cd), copper (Cu), lead (Pb), and nickel (Ni) in rice crop, especially in the grains. Rice plants uptake and accumulate PTEs leading to their entry into the food chain. Consumption of rice contaminated with PTEs disturbs the human metabolism as PTEs interfere with different physiological/molecular mechanisms causing various health problems such as weak bones; skin problems; respiratory, cardiovascular, endocrine, nervous, reproductive, and hepatic disorders; and cancer. Possible non-carcinogenic and carcinogenic health risks have been determined in some studies by following the guidelines provided by various governmental or non-governmental agencies. Considering these facts, the present study was conducted to give a broader perspective on rice contamination with various potentially toxic elements, their bioconcentration in rice, associated health risks in human beings, and strategies for bioremediation of soil and water resources to eliminate PTEs.