Fertilizer rust game11/9/2023 It begins to tarnish on contact with air, thereby forming a complex mixture of compounds, depending on the given conditions. Lead is a bright silvery metal, slightly bluish in a dry atmosphere. Lead is a highly toxic metal whose widespread use has caused extensive environmental contamination and health problems in many parts of the world. Arsenic is a protoplastic poison since it affects primarily the sulphydryl group of cells causing malfunctioning of cell respiration, cell enzymes and mitosis (Gordon & Quastel, 1948). Deliberate consumption of arsenic in case of suicidal attempts or accidental consumption by children may also result in cases of acute poisoning (Mazumder, 2008 Saha et al., 1999). Drinking water may get contaminated by use of arsenical pesticides, natural mineral deposits or inappropriate disposal of arsenical chemicals. Humans may encounter arsenic by natural means, industrial source, or from unintended sources. Arsenic is the twentieth most abundant element on earth and its inorganic forms such as arsenite and arsenate compounds are lethal to the environment and living creatures. It has a semimetallic property, is prominently toxic and carcinogenic, and is extensively available in the form of oxides or sulfides or as a salt of iron, sodium, calcium, copper, etc. Figure 1 shows the global production and consumption of selected toxic metals during 1850–1990 (Nriagu, 1996).Īrsenic is one of the most important heavy metals causing disquiet from both ecological and individual health standpoints (Hughes et al., 1988). Various sources of heavy metals include soil erosion, natural weathering of the earth's crust, mining, industrial effluents, urban runoff, sewage discharge, insect or disease control agents applied to crops, and many others (Morais et al., 2012). Heavy metals enter the surroundings by natural means and through human activities. The most commonly found heavy metals in waste water include arsenic, cadmium, chromium, copper, lead, nickel, and zinc, all of which cause risks for human health and the environment (Lambert et al., 2000). Heavy metals are significant environmental pollutants and their toxicity is a problem of increasing significance for ecological, evolutionary, nutritional and environmental reasons (Jaishankar et al., 2013 Nagajyoti et al., 2010). 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. 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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