ABSTRACT
Due to their toxic and bio-accumulative nature in the environment, heavy metals are regarded as environmental pollutants. Their natural sources include the weathering of rocks and volcanic eruptions, while mining, industrial, and farming activities are anthropogenic sources. Some metals and metalloids are essential for life as micronutrients and play significant physiological and biochemical roles, and their deficiency or excess can disturb the metabolism. However, due to their role in causing toxicity, heavy metals are immense public health concerns. Metal-induced toxicity and carcinogenicity include many mechanistic aspects. Each metal has distinct features and physico-chemical properties that confer its individual toxicological mechanism of action. Metal toxicity is basically the deposition of heavy metals in lethal amounts in body soft tissues. Heavy metals are lethal to plants, animals, and humans, even at very low concentrations. This chapter focuses on the sources of heavy metals, the basic mechanism of heavy metal contamination, and their transmission from soil to plants in biota and food chains.
