The essential heavy metals are elements, which are indispensable for plant and animals, which play a vital role in biological processes and entire metabolism and may be required in living organism in different concentrations. Their category includes lead, cadmium, mercury, aluminum and arsenic, being able to exert toxic effects even at low concentrations. The nonessential heavy metals do not possess biological functions in living organisms, being non-essential to metabolic system, both for plants and animals. Regarding their functions in biological systems, heavy metals can be essential and nonessential. Among the heavy metals and the most toxic metalloids are chromium, mercury, arsenic, cadmium, lead, nickel, copper, zinc, but the most common heavy metals in the environment are chromium, manganese, nickel, lead, cadmium, copper and zinc. These elements are naturally present in the environment, but on which modern industrialization and urbanization, anthropogenic activities and use of fertilizers, led to increased levels of these metals in the environment and implicitly to a high exposure of living things to them. Heavy metals are among the most investigated pollutants and received a higher attention by researchers, because of their toxicity. Heavy metal toxicity is a concern of ecological, nutritional, evolutionary and environmental reasons. Pollution or contamination of the environment with heavy metals is a major concern, due to their capacity to bioaccumulate and persistence in the environment, non-biodegradable nature, contaminate the food chains and their toxicity on the environment and living organisms (humans, animals and plants). Heavy metals (HM) represent a group of metallic elements and metalloids characterized by a relatively density higher than 5 g/cm 3, an atomic number greater than 20 and with properties like conductance of heat, current and luster surface. This chapter present the main characteristics of heavy metals, the sources of contamination of exposure, as well as their toxicity on some environmental segments and especially on living organisms. There is a growing interest from researchers to detect various physical, physical-chemical or microbiological methods to reduce or eliminate the presence of these metals, especially from surface or wastewater, which are mainly responsible for food contamination. Their toxicity is dependent on factors such as dose, route of exposure, time of exposure, level of concentration, as well as age, gender, genetics, and nutritional status of exposed individuals. Studies have also shown that heavy metals can have important effects, including on plants or animals. These metals can reach the human body through food, water or air, where they have the property to accumulate in various tissues and organs for long periods of time and to produce serious effects on certain organs and the proper functioning of the body. Heavy metals are elements who exist naturally in the environment, but rapid urbanization and industrialization led to increased levels of these metals.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |