Arsenic Poisoning In Bangladesh Pdf Free
The mechanisms for how arsenic decreases cholinesterase activity have not yet been documented. Arsenic compounds are known as potent inhibitor of many enzymes  and the reaction between the arsenic and the free sulfhydryl groups of enzymes may underlie the mechanism of this inhibition. However, cholinesterase does not have the structural features suitable for binding with arsenic. Cholinesterase has been found to contain cysteine only in the form of disulphide bridges and not as free thiol . Moreover, other reactant chemicals in the sulfhydryl group such as iodoacetamide or mercury compounds did not inhibit cholinesterase . Therefore, arsenic reduces the activity of cholinesterase probably due to other mechanisms rather than the direct binding to the enzyme.
Arsenic Poisoning In Bangladesh Pdf Free
Arsenic contamination of groundwater in different parts of the world is an outcome of natural and/or anthropogenic sources, leading to adverse effects on human health and ecosystem. Millions of people from different countries are heavily dependent on groundwater containing elevated level of As for drinking purposes. As contamination of groundwater, poses a serious risk to human health. Excessive and prolonged exposure of inorganic As with drinking water is causing arsenicosis, a deteriorating and disabling disease characterized by skin lesions and pigmentation of the skin, patches on palm of the hands and soles of the feet. Arsenic poisoning culminates into potentially fatal diseases like skin and internal cancers. This paper reviews sources, speciation, and mobility of As and global overview of groundwater As contamination. The paper also critically reviews the As led human health risks, its uptake, metabolism, and toxicity mechanisms. The paper provides an overview of the state-of-the-art knowledge on the alternative As free drinking water and various technologies (oxidation, coagulation flocculation, adsorption, and microbial) for mitigation of the problem of As contamination of groundwater.
The main sorbent for As(III) and As(V) is iron oxyhydroxides (FeOOH). As(V) gets more strongly attached to iron oxyhydroxides as compared to As(III). Clay or clayey soil contains more FeOOH when compared to sandy soil, and therefore, clayey soil has more arsenic. Clayey soils are less toxic than sandy soils because in clayey soils arsenic is strongly adsorbed. In an anaerobic condition under microbial action or reduction conditions, arsenic bound to iron oxyhydroxides is freely released. There are bacteria that are capable of reducing Fe(III) as well as oxidizing Fe(II). It is also reported that reduction of arsenic from V to III state has taken place without desorption from iron oxyhydroxides [118, 119]. In aerobic conditions, iron oxyhydroxides become insoluble and therefore there is lesser release of arsenic. The arsenic and iron relation is dynamic in nature and plays an important role in aging of the paddy field. Amorphous iron oxides have strong affinity for arsenic.
Lab animals showed symptoms of PNS abnormalities, anemia, leukopenia, melanosis, cardiac malfunction, and liver damage. Surprisingly, these symptoms vanished when exposure got refrained [40, 94, 95]. Acute and sub-acute symptoms demarcate arsenic poisoning whereas chronic poisoning is rare [40, 84, 132]. This is because of immediate follow-up of detoxification and excretion processes [40, 132]. External uptaking of arsenic compounds affects the spleen, kidney, liver, and lungs; these compounds can then mobilize to ectodermal tissues such as nails and hair as these tissues are rich in sulfur-containing proteins .
In order to check the effects of arsenic, long-term actions are required from mining, metal smelting and refining, combustion of low-grade coal, pesticide use, and timber treatment. Most importantly, in these As affected with high groundwater arsenic, action is needed to reduce the intake of arsenic from drinking water and food [64, 130], which may include provision of safe drinking water, regular monitoring of the arsenic level in groundwater, awareness among dependents, designing and developing arsenic removal technologies, discriminating between high-arsenic and low-arsenic water sources by painting hand pumps in different colors (e.g., red and green) , or adapting sediment-coloring tools [63, 64]. In addition to these, monitor high-risk populations for early signs of arsenic poisoning, usually skin problems and other effects [55, 56].