Арсеник улануы және оның салдары

Illness from ingesting arsenic
Through drinking water, more than 200 million people globally are exposed to higher than safe levels of arsenic. Acute poisoning is uncommon. The toxicity of arsenic has been described as far back as 1500 BC in the Ebers papyrus.

Ingesting large amounts of arsenic can cause symptoms similar to food poisoning, with abdominal pain, nausea, vomiting, and diarrhea starting within hours. Bloody diarrhea can cause severe fluid loss, resulting in hypovolemic shock. Inhaling arsine gas – the most toxic form of arsenic – causes a multisystem disease starting 2 to 24 hours after inhalation. Symptoms include gastrointestinal distress, headache, weakness, difficulty breathing, kidney and liver dysfunction, and the destruction of red blood cells. Some experience general thickening of the skin on the palms and soles of the feet, or small thickened areas.

Arsenic poisoning is caused by incidental ingestion or inhalation of arsenic, typically from drinking contaminated well water, eating food cooked in contaminated water, or being exposed to arsenic containing pesticides, folk medicines, or industrial chemicals. Arsenic levels in the groundwater vary from around 0.5 parts per billion to 5000 parts per billion, depending on an area's geologic features, and possible presence on industrial waste. The highest groundwater arsenic levels have been recorded in Brazil, Cambodia, Afghanistan, Australia, and Bangladesh. In the US, the U. S. Geological Survey estimates that the median groundwater concentration is 1 μg/L or less, although some groundwater aquifers, particularly in the western United States, can contain much higher levels. For example, median levels in Nevada were about 8 μg/L but levels of naturally occurring arsenic as high as 1000 μg/L have been measured in the United States in drinking water. Groundwater associated with volcanics in California contain As at concentrations ranging up to 48,000 μg/L, with As bearing sulfide minerals as the main source. Geothermal waters on Dominica in the Lesser Antilles also contain concentrations of As >50 μg/L. In Wisconsin, As concentrations of water in sandstone and dolomite aquifers were as high as 100 μg/L. Oxidation of pyrite hosted by these formations was the likely source of the As. In the Piedmont of Pennsylvania and New Jersey, groundwater in Mesozoic age aquifers contains elevated levels of As—domestic well waters from Pennsylvania contained up to 65 μg/L, whereas in New Jersey the highest concentration measured recently was 215 μg/L. Organic arsenic is less harmful than inorganic arsenic. Seafood is a common source of the less toxic organic arsenic in the form of arsenobetaine. Because of its high toxicity, arsenic is seldom used in the Western world, although in Asia it is still a popular pesticide. Arsenic is mainly encountered occupationally in the smelting of zinc and copper ores. In the United States, Schoof et al. estimated an average adult intake of 3.2 μg/day, with a range of 1–20 μg/day. Estimates for children were similar. Food also contains many organic arsenic compounds. The key organic arsenic compounds that can be routinely found in food (depending on food type) include monomethylarsonic acid (MMAsV), dimethylarsinic acid (DMAsV), arsenobetaine, arsenocholine, arsenosugars, and arsenolipids. DMAsV or MMAsV can be found in various types of fin fish, crabs, and mollusks, but often at very low levels. Arsenobetaine is the major form of arsenic in marine animals, and is considered nontoxic. Arsenocholine, which is mainly found in shrimp, is chemically similar to arsenobetaine, and is considered to be "essentially nontoxic". Although arsenobetaine is little studied, available information indicates it is not mutagenic, immunotoxic, or embryotoxic. Arsenosugars and arsenolipids have recently been identified. Exposure to these compounds and toxicological implications are currently being studied. Arsenosugars are detected mainly in seaweed but are also found to a lesser extent in marine mollusks. Studies addressing arsenosugar toxicity, however, have largely been limited to in vitro studies, which show that arsenosugars are significantly less toxic than both inorganic arsenic and trivalent methylated arsenic metabolites. It has been found that rice is particularly susceptible to accumulation of arsenic from soil. Rice grown in the United States has an average 260 ppb of arsenic, according to a study; but U. S. arsenic intake remains far below World Health Organization recommended limits. China has set a standard for arsenic limits in food (150 ppb), as levels in rice exceed those in water. The European Commission (2000) reports that levels of arsenic in air range 0–1 ng/m3 in remote areas, 0.2–1.5 ng/m3 in rural areas, 0.5–3 ng/m3 in urban areas, and up to about 50 ng/m3 in the vicinity of industrial sites. Based on these data, the European Commission (2000) estimated that in relation to food, cigarette smoking, water, and soil, air contributes less than 1% of total arsenic exposure.

The use of lead arsenate pesticides has been effectively eliminated for over 50 years. However, because of the pesticide's environmental persistence, it is estimated that millions of acres of land are still contaminated with lead arsenate residues. This presents a potentially significant public health concern in some areas of the United States (e. g., New Jersey, Washington, and Wisconsin), where large areas of land used historically as orchards have been converted into residential developments. Some modern uses of arsenic based pesticides still exist. Chromated copper arsenate has been registered for use in the United States since the 1940s as a wood preservative, protecting wood from insects and microbial agents. In 2003, manufacturers of chromated copper arsenate instituted a voluntary recall of residential uses of wood treated with the chemical. The Environmental Protection Agency Act 2008 final report stated that chromated copper arsenate is still approved for use in nonresidential applications, such as in marine facilities (pilings and structures), utility poles, and sand highway structures.

Exposure studies in the copper smelting industry are much more extensive and have established definitive links between arsenic, a by product of copper smelting, and lung cancer via inhalation. Dermal and neurological effects were also increased in some of these studies. Although as time went on, occupational controls became more stringent and workers were exposed to reduced arsenic concentrations, the arsenic exposures measured from these studies ranged from about 0.05 to 0.3 mg/m3 and are significantly higher than airborne environmental exposures to arsenic (which range from 0 to 0.000003 mg/m3).

Arsenite inhibits not only the formation of acetyl CoA but also the enzyme succinic dehydrogenase. Arsenate can replace phosphate in many reactions. It is able to form Glc 6 arsenate in vitro; therefore it has been argued that hexokinase could be inhibited. (Eventually this may be a mechanism leading to muscle weakness in chronic arsenic poisoning.) In the glyceraldehyde 3 phosphate dehydrogenase reaction arsenate attacks the enzyme bound thioester. The formed 1 arseno 3 phosphoglycerate is unstable and hydrolyzes spontaneously. Thus, ATP formation in glycolysis is inhibited while bypassing the phosphoglycerate kinase reaction. (Moreover, the formation of 2,3 bisphosphoglycerate in erythrocytes might be affected, followed by a higher oxygen affinity of hemoglobin and subsequently enhanced cyanosis.) As shown by Gresser (1981), submitochondrial particles synthesize adenosine 5' diphosphate arsenate from ADP and arsenate in presence of succinate. Thus, by a variety of mechanisms arsenate leads to an impairment of cell respiration and subsequently diminished ATP formation. This is consistent with observed ATP depletion of exposed cells and histopathological findings of mitochondrial and cell swelling, glycogen depletion in liver cells and fatty change in liver, heart and kidney. Experiments demonstrated enhanced arterial thrombosis in a rat animal model, elevations of serotonin levels, thromboxane A[2] and adhesion proteins in platelets, while human platelets showed similar responses. The effect on vascular endothelium may eventually be mediated by the arsenic induced formation of nitric oxide. It was demonstrated that +3 As concentrations substantially lower than concentrations required for inhibition of the lysosomal protease cathepsin L in B cell line TA3 were sufficient to trigger apoptosis in the same B cell line, while the latter could be a mechanism mediating immunosuppressive effects. Its comutagenic effects may be explained by interference with base and nucleotide excision repair, eventually through interaction with zinc finger structures. Dimethylarsinic acid, DMA(V), caused DNA single strand breaks resulting from inhibition of repair enzymes at levels of 5 to 100 mM in human epithelial type II cells. MMA(III) and DMA(III) were also shown to be directly genotoxic by effectuating scissions in supercoiled ΦX174 DNA. Increased arsenic exposure is associated with an increased frequency of chromosomal aberrations, micronuclei and sister chromatid exchanges. An explanation for chromosomal aberrations is the sensitivity of the protein tubulin and the mitotic spindle to arsenic. Histological observations confirm effects on cellular integrity, shape and locomotion. DMA(III) is able to form reactive oxygen species by reaction with molecular oxygen. Resulting metabolites are the dimethylarsenic radical and the dimethylarsenic peroxyl radical. Both DMA(III) and DMA(V) were shown to release iron from horse spleen as well as from human liver ferritin if ascorbic acid was administered simultaneously. Thus, formation of reactive oxygen species can be promoted. Moreover, arsenic could cause oxidative stress by depleting the cell's antioxidants, especially the ones containing thiol groups. The accumulation of reactive oxygen species like that cited above and hydroxyl radicals, superoxide radicals and hydrogen peroxides causes aberrant gene expression at low concentrations and lesions of lipids, proteins and DNA in higher concentrations which eventually lead to cellular death. In a rat animal model, urine levels of 8 hydroxy 2' deoxyguanosine (as a biomarker of DNA damage byreactive oxygen species) were measured after treatment with DMA(V). In comparison to control levels, they turned out to be significantly increased. This theory is further supported by a cross sectional study which found elevated mean serum lipid peroxides in the As exposed individuals which correlated with blood levels of inorganic arsenic and methylated metabolites and inversely correlated with nonprotein sulfhydryl (NPSH) levels in whole blood. Another study found an association of As levels in whole blood with the level of reactive oxidants in plasma and an inverse relationship with plasma antioxidants. A finding of the latter study indicates that methylation might in fact be a detoxification pathway with regard to oxidative stress: the results showed that the lower the As methylation capacity was, the lower the level of plasma antioxidant capacity. As reviewed by Kitchin (2001), the oxidative stress theory provides an explanation for the preferred tumor sites connected with arsenic exposure. An experiment by Zhong et al. (2001) with arsenite exposed human lung A549, kidney UOK123, UOK109 and UOK121 cells isolated eight different DNA fragments by methylation sensitive arbitrarily primed polymerase chain reactions. It turned out that six of the fragments were hyper and two of them were hypomethylated. MRP1 overexpressing lung tumor GLC4/Sb30 cells poorly accumulate arsenite and arsenate. This is mediated through MRP 1 dependent efflux. The efflux requires glutathione, but no arsenic glutathione complex formation. Although many mechanisms have been proposed, no definite model can be given for the mechanisms of chronic arsenic poisoning. The prevailing events of toxicity and carcinogenicity might be quite tissue specific. Current consensus on the mode of carcinogenesis is that it acts primarily as a tumor promoter. Its co carcinogenicity has been demonstrated in several models. However, the finding of several studies that chronically arsenic exposed Andean populations (as most extremely exposed to UV light) do not develop skin cancer with chronic arsenic exposure, is puzzling.

The two forms of inorganic arsenic, reduced (trivalent As(III)) and oxidized (pentavalent As(V)), can be absorbed, and accumulated in tissues and body fluids. In the liver, the metabolism of arsenic involves enzymatic and non enzymatic methylation; the most frequently excreted metabolite (≥ 90%) in the urine of mammals is dimethylarsinic acid or cacodylic acid, DMA(V). Resulting metabolites are monomethylarsonous acid, MMA(III), and dimethylarsinous acid, DMA(III). Methylation had been regarded as a detoxification process, but reduction from +5 As to +3 As may be considered as a bioactivation instead. Another suggestion is that methylation might be a detoxification if "As[III] intermediates are not permitted to accumulate" because the pentavalent organoarsenics have a lower affinity to thiol groups than inorganic pentavalent arsenics. With regard to carcinogenicity it has been suggested that methylation should be regarded as a toxification. Arsenic, especially +3 As, binds to single, but with higher affinity to vicinal sulfhydryl groups, thus reacts with a variety of proteins and inhibits their activity. It was also proposed that binding of arsenite at nonessential sites might contribute to detoxification. Arsenite inhibits members of the disulfide oxidoreductase family like glutathione reductase and thioredoxin reductase. The remaining unbound arsenic (≤ 10%) accumulates in cells, which over time may lead to skin, bladder, kidney, liver, lung, and prostate cancers. Other forms of arsenic toxicity in humans have been observed in blood, bone marrow, cardiac, central nervous system, gastrointestinal, gonadal, kidney, liver, pancreatic, and skin tissues.

Another aspect is the similarity of arsenic effects to the heat shock response. Short term arsenic exposure has effects on signal transduction inducing heat shock proteins with masses of 27, 60, 70, 72, 90, and 110 kDa as well as metallothionein, ubiquitin, mitogen activated [MAP] kinases, extracellular regulated kinase [ERK], c jun terminal kinases [JNK] and p38. Via JNK and p38 it activates c fos, c jun and egr 1 which are usually activated by growth factors and cytokines. The effects are largely dependent on the dosing regime and may be as well inversed. As shown by some experiments reviewed by Del Razo (2001), reactive oxygen species induced by low levels of inorganic arsenic increase the transcription and the activity of the activator protein 1 (AP 1) and the nuclear factor κB (NF κB) (maybe enhanced by elevated MAPK levels), which results in c fos/c jun activation, over secretion of pro inflammatory and growth promoting cytokines stimulating cell proliferation. Germolec et al. (1996) found an increased cytokine expression and cell proliferation in skin biopsies from individuals chronically exposed to arsenic contaminated drinking water. Increased AP 1 and NF κB obviously also result in an up regulation of mdm2 protein, which decreases p53 protein levels. Thus, taking into account p53's function, a lack of it could cause a faster accumulation of mutations contributing to carcinogenesis. However, high levels of inorganic arsenic inhibit NF κB activation and cell proliferation. An experiment of Hu et al. (2002) demonstrated increased binding activity of AP 1 and NF κB after acute (24 h) exposure to +3 sodium arsenite, whereas long term exposure (10–12 weeks) yielded the opposite result. as well as the pro inflammatory cytokines IL 8 and TNF α. The interference of oxidative stress with signal transduction pathways may affect physiological processes associated with cell growth, metabolic syndrome X, glucose homeostasis, lipid metabolism, obesity, insulin resistance, inflammation, and diabetes 2. Recent scientific evidence has elucidated the physiological roles of the PPARs in the ω hydroxylation of fatty acids and the inhibition of pro inflammatory transcription factors (NF κB and AP 1), pro inflammatory cytokines (IL 1, 6, 8, 12, and TNF α), cell4 adhesion molecules (ICAM 1 and VCAM 1), inducible nitric oxide synthase, proinflammatory nitric oxide (NO), and anti apoptotic factors. Epidemiological studies have suggested a correlation between chronic consumption of drinking water contaminated with arsenic and the incidence of type 2 diabetes. Tests are available to diagnose poisoning by measuring arsenic in blood, urine, hair, and fingernails. The urine test is the most reliable test for arsenic exposure within the last few days. Urine testing needs to be done within 24–48 hours for an accurate analysis of an acute exposure. Tests on hair and fingernails can measure exposure to high levels of arsenic over the past 6–12 months. These tests can determine if one has been exposed to above average levels of arsenic. They cannot predict, however, whether the arsenic levels in the body will affect health. Chronic arsenic exposure can remain in the body systems for a longer period of time than a shorter term or more isolated exposure and can be detected in a longer time frame after the introduction of the arsenic, important in trying to determine the source of the exposure. Hair is a potential bioindicator for arsenic exposure due to its ability to store trace elements from blood. Incorporated elements maintain their position during growth of hair. Thus for a temporal estimation of exposure, an assay of hair composition needs to be carried out with a single hair which is not possible with older techniques requiring homogenization and dissolution of several strands of hair. This type of biomonitoring has been achieved with newer microanalytical techniques like synchrotron radiation based X ray fluorescence spectroscopy and microparticle induced X ray emission. The highly focused and intense beams study small spots on biological samples allowing analysis to micro level along with the chemical speciation. In a study, this method has been used to follow arsenic level before, during and after treatment with arsenious oxide in patients with acute promyelocytic leukemia.

Dimercaprol and dimercaptosuccinic acid are chelating agents that sequester the arsenic away from blood proteins and are used in treating acute arsenic poisoning. The most important side effect is hypertension. Dimercaprol is considerably more toxic than succimer. Dimercaptosuccinic acid monoesters, e. g. MiADMSA, are promising antidotes for arsenic poisoning.

Supplemental potassium decreases the risk of experiencing a life threatening heart rhythm problem from arsenic trioxide.

Beginning in about 3000 BC arsenic was mined and added to copper in the alloying of bronze, but the adverse health effects of working with arsenic led to it being abandoned when a viable alternative, tin, was discovered. In addition to its presence as a poison, for centuries arsenic was used medicinally. It has been used for over 2,400 years as a part of traditional Chinese medicine. In the western world, arsenic compounds, such as salvarsan, were used extensively to treat syphilis before penicillin was introduced. It was eventually replaced as a therapeutic agent by sulfa drugs and then by other antibiotics. Arsenic was also an ingredient in many tonics (or "patent medicines"). In addition, during the Elizabethan era, some women used a mixture of vinegar, chalk, and arsenic applied topically to whiten their skin. This use of arsenic was intended to prevent aging and creasing of the skin, but some arsenic was inevitably absorbed into the blood stream. During the Victorian era (late 19th century) in the United States, U. S. newspapers advertised "arsenic complexion wafers" that promised to remove facial blemishes such as moles and pimples. By the 19th century, it had acquired the nickname "inheritance powder", perhaps because impatient heirs were known or suspected to use it to ensure or accelerate their inheritances. In post WW1 Hungary, arsenic extracted by boiling fly paper was used in an estimated 300 murders by the Angel Makers of Nagyrév. In imperial China, arsenic trioxide and sulfides were used in murder, as well as for capital punishment for members of the royal family or aristocracy. Forensic studies have determined that the Guangxu Emperor (d. 1908) was murdered by arsenic, most likely ordered by the Empress Dowager Cixi or Generalissimo Yuan Shikai. Likewise, in ancient Korea, and particularly in the Joseon Dynasty, arsenic sulfur compounds had been used as a major ingredient of sayak (사약; 賜藥), which was a poison cocktail used in capital punishment of high profile political figures and members of the royal family. Due to social and political prominence of the condemned, many of these events were well documented, often in the Annals of Joseon Dynasty; they are sometimes portrayed in historical television miniseries because of their dramatic nature. One of the worst incidents of arsenic poisoning via well water occurred in Bangladesh, which the World Health Organization called the "largest mass poisoning of a population in history" recognized as a major public health concern. The contamination in the Ganga Brahmaputra fluvial plains in India and Padma Meghna fluvial plains in Bangladesh demonstrated adverse impacts on human health. Arsenic poisoning from exposure to groundwater is believed to be responsible for the illness experienced by those that witnessed the 2007 Carancas impact event in Peru, as local residents inhaled steam which was contaminated with arsenic, produced from groundwater which boiled from the intense heat and pressure produced by a chondrite meteorite impacting the ground.

In the U. S. in 1975, under the authority of the Safe Drinking Water Act, the U. S. Environmental Protection Agency determined the National Interim Primary Drinking Water Regulation levels of arsenic (inorganic contaminant – IOCs) to be 0.05 mg/L (50 parts per billion – ppb). Throughout the years, many studies reported dose dependent effects of arsenic in drinking water and skin cancer. In order to prevent new cases and death from cancerous and non cancerous diseases, the Safe Drinking Water Act directed the Environmental Protection Agency to revise arsenic's levels and specified the maximum contaminant level (MCL). MCLs are set as close to the health goals as possible, considering cost, benefits and the ability of public water systems to detect and remove contaminants using suitable treatment technologies. In 2001, Environmental Protection Agency adopted a lower standard of MCL 0.01 mg/L (10 ppb) for arsenic in drinking water that applies to both community water systems and non transient non community water systems.

Arsenic removal technologies are traditional treatment processes which have been tailored to improve removal of arsenic from drinking water. Although some of the removal processes, such as precipitative processes, adsorption processes, ion exchange processes, and separation (membrane) processes, may be technically feasible, their cost may be prohibitive.

Arsenic exposure through groundwater is highly concerning throughout the perinatal period. Pregnant people are a high risk population because not only are they at risk for adverse outcomes, but in utero exposure also poses health risks to the foetus. There is a dose dependent relationship between perinatal exposure to arsenic and infant mortality, meaning that infants born to people exposed to higher concentrations, or exposed for longer periods of time, have a higher mortality rate. Studies have shown that ingesting arsenic through groundwater during pregnancy poses dangers to the pregnant person including, but not limited to abdominal pain, vomiting, diarrhea, skin pigmentation changes, and cancer. Research has also demonstrated that arsenic exposure also causes low birth weight, low birth size, infant mortality, and a variety of other outcomes in infants. Some of these effects, like lower birth rate and size may be due to the effects of arsenic on weight gain during pregnancy.