Heavy metals are found naturally in the earth, and become concentrated as a result of human
caused activities. Common sources are from mining and industrial wastes, vehicle emissions, lead-
acid batteries, fertilisers, paints, treated woods, aging water supply infrastructure, and microplastics
floating in the world's oceans. Heavy metals enter plant, animal and human tissues via air
inhalation, diet and manual handling. Most of these chemicals including mercury, lead, cadmium
and their compounds are among the most common and highly toxic substances capable of
accumulation in living organisms. Heavy metals with excessive exposure to environmental objects
behave like ecotoxicants that negatively affect not only individual organisms, but also the
ecosystem as a whole
