**4. Intake of heavy metal in human body through vegetables**

The industries are growing day by day in our country. The waste chemical contaminated water from these industries is directly thrown in river, sea, etc. Also the wastes, garbage from city is thrown in the water. This is the major reason behind the contamination of water. This water is used in many purposes like drinking, agriculture, etc. The contaminated water used in agriculture is absorbed by various vegetables. Resulting the vegetables become contaminated. We the humans use these contaminated vegetables in eating purpose. Once it is ingested in digestive system, it shows poisonous effects on the body as described in **Figure 2**. Heavy metal exposure typically follows this outline: from industries to air, soil, water, and foods, and then to people [55–59]. This heavy metals are existing in a amount of formats. Heavy metals like lead, cadmium, manganese, as well as arsenic could arrive the body by the gastrointestinal system or the entrance of digestive system while eating, drinking, or eating fruits and vegetables. The bulk of bodily heavy metals are transferred from blood to tissues [60, 61]. Red blood cells passes lead to not only the liver but also kidneys, where it is subsequently re-assigned as phosphate salt to the teeth, bone as well as hair [62–64]. Cadmium firstly fixes to blood cells & albumin, formerly to metallothionein in the kidney as well as liver. Later being carried through the blood to the lungs, vapour of manganese disperses over the membrane of lung to the central nervous system (CNS). Water solvable inorganic manganese ions are dispersed in the plasma as well as kidney for renal removal, whereas fat solvable manganese salts are diffused in the colon for faecal removal. Accumulation of Arsenic in the heart, lungs, liver, kidney, muscle, and neural tissues, as well as the skin, nails, and hair, afterward being passed by the circulation.

#### **Figure 2.**

*Cyclic explanation of how vegetables contaminated and its toxic effects on humans.*

#### *Heavy Metal Contamination in Vegetables and Their Toxic Effects on Human Health DOI: http://dx.doi.org/10.5772/intechopen.102651*

Free radicals are known to be produced by some heavy metals, which can cause oxidative stressing as well as other cellular damaging. The method by which free radicals are generated is unique to heavy metal. Heavy metals are acetified by the acid medium of stomach when they are consumed through food or drink. They oxidised to several oxidative states (Zn2+, Cd2+, Pb2+, As2+, As3+, Ag+, Hg2+, etc.) in this acidic media, which can quickly fix to biological molecules like proteins as well as enzymes to create persistent and strong connections. The thio groups are the most prevalent functional groups that heavy metals fixes to (SH group of cysteine and SCH3 group of methionine). Cadmium had shown to bind to cysteine remains in the catalytic surface of human thiol transfers in vitro, consisting thioredoxin reductase, glutathione reductase, as well as thioredoxin [65–70].

Heavy metal-bounded proteins might be able to be useful as a substratum by some enzymes. The heavy metal-bounded protein has an enzyme-substrate complex in a specific pattern, which prevents the enzyme through absorbing any more substrates till it is release. Resulting of the enzyme being inhibited, the product of substratum is not formed, and the heavy metal becomes embedded in the tissue, producing dysfunctions, abnormalities, and damage. Constraining thiol transferases reasons an rise in oxidative pressure and cell damaging. Poisonous arsenic, which can be there in fungicides, herbicides, and insecticides, can damage enzymes' –SH groups, preventing them from catalysing reactions.

As arsenite-inducing protein clustering was found and proved to be concentrationdependending, heavy metals may cause proteins to aggregate. The clusters also comprised a diverse ranging of proteins with roles linked to metabolism, protein portable, synthesis of protein, and protein stability [71–75]. After exposing to equi-toxic quantities of cadmium, arsenite, as well as chromium (Cr(VI)), Saccharomyces cerevisiae (budding yeast) cells gathered aggregated proteins, and the outcome of heavy metals on protein aggregation was altered in this direction: arsenic > cadmium > chromium [76–80]. The effectiveness of this agents' cellular uptake/export, as well as their different modalities of biological action, are likely to determine their in vivo potency to cause protein aggregation.
