Arsenic and Heavy Metal (Cadmium, Lead, Mercury and Nickel) Contamination in Plant-Based Foods

Plant-based foods satisfy more than 70% of the human energy and nutrition requirements. However, such foods may be contaminated by heavy metal(loid)s. The dietary exposure to excessive levels of these contaminants is detrimental to human health. In this chapter, we have reviewed the reported contamination levels of arsenic (As), cadmium (Cd), lead (Pb), mercury (Hg) and nickel (Ni) in cereals, vegetables, fruits, nuts, pulses and plant oils. The reported concentrations in different plant-based foods were up to 2.9 mg As kg−1, 24 mg Cd kg−1, 61 mg Pb kg−1, 0.10 mg Hg kg−1 and 506 mg Ni kg−1. Concentrations of the studied contaminants in plant oils were within permissible levels in all the listed studies. Moreover, Hg was within permissible levels in all the studies. However, some samples of vegetables, fruits, cereals, pulses and nuts were reported to be contaminated by As, Cd, Pb and Ni to levels toxic to humans. The contamination levels in plant-based foods were related to contamination of agricultural soils, irrigation waters, atmosphere and crop inputs. The occurrence of contaminated plant-based foods is more common in the densely populated developing and underdeveloped countries in the world. Wastewater treatment, soil remediation and control of the emission of air pollutants have become increasingly important for sustainable agriculture. In the absence of effective remediation, food plants should not be grown in contaminated areas or near the sources of contamination.