**2. Toxic effects of heavy metals on plants and the human body**

Heavy metal poisoning is caused by the accumulation of certain metals in the body due to exposure through food, water, industrial chemicals, or other sources. While your body needs small amounts of some heavy metals to function normally, such as zinc, copper, chromium, iron, and manganese toxic amounts are harmful. Iron, cobalt, copper, manganese, molybdenum, and zinc are required by humans in adequate amounts. In the human body, these heavy metals are transported and compartmentalized into body cells and tissues binding to proteins, nucleic acids destroying these macromolecules and disrupting their cellular functions. Heavy metals disrupt metabolic functions in two ways: They accumulate and thereby disrupt function in vital organs and glands such as the heart, brain, kidneys, bone, liver, etc. They displace the vital nutritional minerals from their original place, thereby, hindering their biological function. The study on the absorption and accumulation of heavy metals lead, zinc, copper, and cadmium by various plant species around a smelter showed that the accumulation of the metals by plants differed with plant species and their parts [7].

Heavy metals can accumulate and migrate in the soil environment. Metal pollutants in soil may be absorbed by the plants through their roots and vascular system. Once in the body, heavy metals can accumulate over time in your bones, liver, brain, kidneys,

### *Trace Element Determination in Medicinal Plant Samples by ED-XRF Analysis DOI: http://dx.doi.org/10.5772/intechopen.107854*

and heart. Having excess heavy metals in the body can damage vital organs, and cause behavioral changes and difficulties with thinking and memory. The heavy metals most commonly associated with the poisoning of humans are lead, mercury, arsenic, and cadmium. Heavy metal poisoning may occur as a result of industrial exposure, air or water pollution, foods, medicines, improperly coated food containers, or the ingestion of lead-based paints. Zinc reduces the amount of copper your body absorbs, and high doses of zinc can cause a copper deficiency. Gastrointestinal and kidney dysfunction, nervous system disorders, skin lesions, vascular damage, immune system dysfunction, birth defects, and cancer are examples of the complications of heavy metals toxic effects. Heavy metal intoxication is another reason for liver disease, it has great importance due to unnoticed intake of heavy metals by humans and because heavy metals can be present in drinking water, food, and the environment or workplace of affected people. A person who lost his vision and even suddenly became color blind turned out to have an unusual cause for the problems: thallium poisoning. Thallium is a metal that can be absorbed through a skin and can cause neurological problems [7, 8].

Essential and non-essential heavy metals generally produce common toxic effects on plants, such as low biomass accumulation, chlorosis, inhibition of growth and photosynthesis, altered water balance and nutrient assimilation, and senescence, which ultimately cause plant death.

To minimize the detrimental effects of heavy metal exposure and its accumulation, plants have evolved detoxification mechanisms. Such mechanisms are mainly based on chelation and subcellular compartmentalization. Chelation of heavy metals is a ubiquitous detoxification strategy described in wide variety of plants. Among the most significant heavy metals from the point of view of health are mercury, lead, cadmium, nickel, and zinc [6, 7].
