Heavy Metal Contamination in Vegetables and Their Amelioration: A Review

Heavy metal (s) contamination of vegetables is an alarming and significant concern due to its potential health risks for consumers. Heavy metal contamination of vegetables has threatened both food security and human health. Contaminants like lead (Pb), cadmium (Cd), arsenic (As), mercury (Hg) and others can be added to vegetable tissues when present in the soil, water, or through other sources. Anthropogenic activities such as mining, industrialization and agricultural practices like pesticide, fungicide, as well as fertilizer use release heavy metals into the soil, water and atmosphere. Vegetables are essential to the human nutrition, which provide vitamins, minerals and fibres and also have beneficial anti-oxidative properties to maintain normal physiological functions. Vegetables absorb heavy metal(s) and store them in their bodies at levels that can lead to health issues. Even at low concentrations, heavy metals can be highly detrimental to the human body due to the lack of an efficient excretion mechanism. The research on review of heavy metal contamination of vegetable crops and their amelioration have been conducted from various secondary sources of published data. Heavy metal polluted soil leads to reduction in growth due to changes in physiological and biochemical activities which affect the growth and yield of vegetable crops. To mitigate heavy metal contamination, various strategies are soil testing, remediation of contaminated sites, improving agricultural practices and monitoring of water sources, etc. Remediation techniques for reducing heavy metal contamination in vegetables include immobilization using low-cost absorbents (soil amendments), physical and chemical approaches, phytoremediation/bioremediation, chelating agents, microorganisms, transgenic plants, nanotechnology and grafting, etc.