Although it is acknowledged that heavy metals have many adverse health effects and last for a long period of time, heavy metal exposure continues and is increasing in many parts of the world. These metals are quintessential to maintain various biochemical and physiological functions in living organisms when in very low concentrations, however they become noxious when they exceed certain threshold concentrations. Heavy metals are generally referred to as those metals which possess a specific density of more than 5 g/cm 3 and adversely affect the environment and living organisms (Järup, 2003). The main objective of this review is to provide insight into the sources of heavy metals and their harmful effects on the environment and living organisms. The metal distribution in the atmosphere is monitored by the properties of the given metal and by various environmental factors (Khlifi & Hamza-Chaffai, 2010).
Metals are found naturally in the earth's crust and their compositions vary among different localities, resulting in spatial variations of surrounding concentrations. Metals are substances with high electrical conductivity, malleability, and luster, which voluntarily lose their electrons to form cations. This review gives details about some heavy metals and their toxicity mechanisms, along with their health effects.
METALS LOST TO TIME FREE
This can lead to various disorders and can also result in excessive damage due to oxidative stress induced by free radical formation. Metal toxicity depends upon the absorbed dose, the route of exposure and duration of exposure, i.e. Various public health measures have been undertaken to control, prevent and treat metal toxicity occurring at various levels, such as occupational exposure, accidents and environmental factors. Few metals, such as aluminium, can be removed through elimination activities, while some metals get accumulated in the body and food chain, exhibiting a chronic nature. They sometimes act as a pseudo element of the body while at certain times they may even interfere with metabolic processes. The toxic effects of these metals, even though they do not have any biological role, remain present in some or the other form harmful for the human body and its proper functioning.
Heavy metal toxicity has proven to be a major threat and there are several health risks associated with it.
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