Author:	ghanashyam sharma
Entry Date:	2006-10-11
Title:	Arsenic exposure and the problems
1. What is Arsenic? Arsenic ? a metalloid element ? is a natural part of the earth's crust in some parts of the world and may be found in water that has flowed through arsenic-rich rocks. Arsenic is also emitted into the atmosphere by high-temperature processes such as coal-fired power generation plants, burning vegetation and volcanic action. High concentrations of arsenic in drinking-water are found in various parts of the world including Argentina, Bangladesh, Chile, China, Hungary, India (West Bengal), Mexico, Nepal, Pakistan, Thailand, USA, and Viet Nam. A variety of instrumental techniques available for the determination of arsenic in water and air. (ITS Environmental Health Criteria, No. 224: Arsenic)  Domestic demand for arsenic in the wood preservative industry was relatively unchanged. World production of arsenic trioxide in tons as follows (1996): Belgium 2, 000, Chili 6, 500, China 13, 000, France 4, 000, Kazakhstan 1, 500, Mexico 4, 500, Namibia 2, 300, Philippines 2, 000, Russia 1, 500, Others Countries 3, 000. World resources of copper and lead contain about 11 million tons of arsenic. Substantial resources of arsenic occur in copper ores in northern Peru and the Philippines and in copper-gold ores in Chile. In addition, world gold resources, particularly in Canada, contain substantial resources of arsenic. (USGS, 1997). Arsenic is an element with atomic number of 33. The most common form of the element is a silver-grey brittle crystalline solid. Given below are some of its properties:     Atomic weight 74.9 Specific gravity 5.73 Melting point 817degree Celsius at 28 atm Boiling point 613degree Celsius (sublimes) Vapor pressure 1 mmHg 372degree Celsius     When arsenic is heated in air, it will burn and form a white smoke consisting of arsenic trioxide (As203). Carcinogen category notice: Category 1. Established human carcinogen known to be carcinogenic to humans. There is sufficient evidence to establish a causal association between human exposure to these substances and the development of cancer.             Organic and Inorganic Form of Arsenic   Arsenic can exist in different forms. Organic forms of arsenic are associated with organic carbon. Biological molecules, like the protein, DNA and lipids that make up your body, are based on carbon. These are called organic molecules, and they include all carbon-containing molecules except for carbon dioxide (CO2) or carbonic acid (H2CO3). The organic carbon is shown in green below. Arsenic can be incorporated into organic compounds like monomethylarsonic acid (CH3AsO (OH) 2), arsenobetaine ((CH3)3As+CH2COOH), arsenocholine ((CH3)3As+CH2CH2OH), and Paris green (Cu (CH4COO) 2.3Cu (AsO2)2). Inorganic forms of arsenic include many solid minerals, such as orpiment (As2S3) and arsenopyrite (FeAsS). There are also soluble inorganic forms like arsenious acid (H3AsO3), and arsenic acid (H3AsO4), which are the compounds of concern in drinking water. Arsenious acid has a valence state of +3, which may be written as As (III), and arsenic acid is As (V), with a valence state of +5. 2. Sources of Arsenic     Natural sources:   Rock/soil: Earth?s crust contains (on average) 2-5 ppm arsenic, though some kinds of minerals have much higher concentrations of arsenic. Some examples of arsenic minerals are arsenopyrite, realgar, orpiment, arsenolite. Weathering of these minerals will result in some arsenic getting into water and air.  Volcanic activity can release large amounts of arsenic to the environment Every year, natural sources contribute about 1/3 of the total annual release of arsenic to the atmosphere. Most of this comes from volcanoes. Groundwater in contact with rocks that are high in arsenic may contain high concentrations of arsenic ? this is a natural source of arsenic. Many of the world?s most troublesome problem spots are due to naturally high in arsenic in groundwater. In the oceans, some animals and plants make organic arsenic compounds. These can become quite concentrated in an organism, but they are generally of low toxicity even though they contain arsenic.        3. Who is at risk? Studies in humans indicate that there is considerable variation among different individuals. Sensitive individuals in exposed populations often begin to display one or more of the characteristic signs of arsenic toxicity at oral intakes of around 20 micro- grams (?g) per kilogram of body weight per day (about 1000 to 1500 ?g/day for an adult ? ?g is one-millionth of a gram). While some humans can ingest over 150 ?g/kg/day with- out any apparent ill-effects. There is no particular age group that is especially sensitive to arsenic, but children may have higher environmental exposure than adults because of their smaller body weight and because they play outside. Elevated levels of arsenic in soil (due either to natural mineral deposits or to contamination from human activities) can lead to some exposure from ingesting soil. This is a particular exposure pathway for small children who swallow small amounts of soil whil playing. Manufacturing (smelting) of copper and other metals often releases inorganic arsenic into the air. Thus, workers in metal smelters and nearby residents are exposed to elevated arsenic levels and may have increased risk. There are also low levels of arsenic in cigarette smoke. Therefore people who smoke will have slightly higher risk than non- smokers to arsenic. 4. Normal exposure to arsenic  Humans, normal exposure to arsenic Contact with arsenic goes back more than 5000 years. We know this because from ?tzi, the ?Iceman?, who was preserved in a glacier in the mountains of the Italian Alps, contained high levels of the element. His exposure to arsenic is thought to indicate that he was a coppersmith by trade, since the smelting of this metal is often from ores that are rich in arsenic. The average daily intake of arsenic in a normal diet can be anything up to 1 milligram, depending on the kinds of food eaten. Some foods contain relatively large amounts, although not at the levels that might affect those who eat them. Plaice and oysters have 4 ppm, mussels 120 ppm and prawns as much as 175 ppm, but the arsenic clearly does them no harm, nor does it affect those who eat them. The arsenic is in the form of arsenobetaine, and although this is readily absorbed from the gut, it is also rapidly excreted in the urine. The allowable food residue is limited by law to 1.4 mg/kg. The exposure limit for arsine gas is 0.05 ppm (0.002 mg/m3). Organic arsenicals such as arsphenamine, acetarsone etc. tend to release arsenic slowly and are therefore less likely to cause acute poisoning. The total amount in human body is about 7 mg but varies between 0.5 and 15 mg. Different tissues contain different amounts :   Blood 2-9 micrograms per litre of blood Bone 0.1-1.6 ppm            Tissue 0.1-1.6 ppm Hair 1 ppm Arsenic in animals Despite its notoriety as a deadly poison, arsenic is an essential trace element for some animals, although the necessary intake may be as low as 0.01 milligrams per day. Chickens and rats that are fed an arsenic-free diet have stunted growth. The reason for this need is not clearly understood but it is believed to be linked to the metabolism of the essential amino acid arginine. Several marine algae and shrimps contain organic arsenic compounds in the form of arseno-sugars and arsenobetaine. Arsenic was considered to have a stimulatory effect on animals. Arsenic was exploited by unscrupulous racehorse trainers to improve an animal?s chances of winning. If arsenic is detected in the animal?s urine, and exceeds 50 micrograms per littre, this is a sure sign of its having been doped in this way. Another, more legitimate use, of arsenic was to fatten poultry and pigs. The compound used for that purpose was roxarsone, a derivative of arsenic acid   5. HEALTH EFFECTS - Researches at the University California, program in arsenic health effects research School of Public Health and Centre for Occupational and Environmental Health University of California, Berkeley (1998) provided the following accomplishment on arsenic studies: ?         Provided definitive evidence (from studies conducted in Argentina and Chile) that arsenic is a potent cause of human bladder cancer. ?         Provided definitive evidence (from studies conducted in Argentina and Chile) that arsenic is a potent cause of human lung cancer. ?         Demonstrated results which indicate that epidemiological and experimental human data do not support the methylation hypothesis. ?         Showed that with exposure to water containing around 600 ??g/L, 1 in 10 adult cancer deaths may be due to arsenic-caused cancers, the highest environmental cancer risk ever reported. ?         Identified a dose-response relationship between arsenic exposure and bladder cell micronuclei, a genotoxic marker of effect. ?         Identified a preliminary dose-response relationship between arsenic concentration in well water in India and the occurrence of kurtosis and hyperpigmentation. ?         Studies currently underway in India, Chile and the US, will allow projection of cancer risks with individual exposure data. Chronic Effects of Arsenic After a few years of continued low level of arsenic exposure, many skin ailments appears i.e. Hypopigmentation (white spot), Hyperpigmentation (dark spots), collectively called Melanosis and keratosis (breakup of the skins and on hands and feet).After a letency of 10 years, skin cancers appear. After a latency of 29-30 years, internal cancers-particularly bladder and lung. These all have been seen in Taiwan and in Chilie The number of cancers expected in bangladesh from the exposure already undergone can be very roughly estimated by using "defalut" (lower exposure of 0. 05 ppm (Bangladesh standard) - the risk 1 %) there are 20,000, 000 to 70, 000, 000 exposed persons at levels between 0. 05 ppm and 0.5 ppm. (professor Wilson, Havard University, 1999:   6. Carcinogen Category (Confirmed Human Carcinogen)  Arsenic poisoning does cause a variety of systemic problems when and if an individual does get the toxic of arsenic poisoning. The typical symptoms are; diaphoresis, muscle spasms, nausea, vomiting, abdominal pain, garlic odour to the breath, Diarrhoea, anuria, dehydration, hypertension, cardiovascular collapse, aplastic anaemia and death. The degree to which symptoms a person has will be determined by the severity of the exposure. Possible methods of exposure to toxic substances is common to all products. The possible methods of exposure are contact, ingestion and inhalation.  The first method is by contact and when the substances is arsenic the initial complication is a corrosive effect to the dermal layers. Over a prolonged contact exposure the resulting symptoms can be very dangerous and can cause focal hyperaemia, which means it decreases to blood flow to your arteries and veins and vesicular eruptions            The second possible method of poisoning with an arsenic compound is by ingestion. The ingestion of arsenic will typically lead to the development of symptoms within thirty minutes. The initial symptoms may include a metallic taste in the mouth, hypersalivation, and dysphagia. The progression of symptoms would then include; vomiting, cramps, diaphoresis, breath odour (garlic like), and diarrhoea. If the exposure was of a large concentration then the progression of the arsenic poisoning event would lead to seizures, electrolyte disturbances and systemic shock. An exposure of an individual to arsenic that has resulted from a large quantity or concentration usually will result in death. If death does not occur with in a few hours then death will occur during the next few days due to renal failure. The third method of exposure is by inhalation. The inhalation of arsenic compounds can lead to inflammation of the mucous membranes of the nasal and oral pharyngeal passage ways. The process may be delayed by this type of exposure because the concentration may be lower, but the end result will be the same symptoms as arsenic poisoning by contact, and by ingestion regardless of the method of the exposure toxic event can end in the same result, death!        Arsenic is a metal compound that can easily find its way into the environment and the human population. The substance is found in our water, soil, food products and eventually, use. Even though we have governmental guidelines for controlling such toxic "substances" or "compounds" on a daily basis, we drink contaminated water and eat contaminated food products. This will lead to some degree of arsenic poisoning in each of us, according to Joe Harrison the technical director of Water Quality Association. Daily consumption of water with greater than 50 micrograms per liter of arsenic, less than 1 % of the fatal dose, can lead to problems with skin, circulatory and nervous systems. Greater problems can occur if the arsenic poisoning is of a chronic nature and resulting in neural disorders, vital organ damage and eventually death. Arsenic is a compound that should be more closely monitored by parents, teachers and children because of its fatal results. The three main methods of exposure are contact, ingestion and inhalation. Regardless of the method of exposure all can produce basically the same symptoms           7. Disease associated with arsenic exposure?            Based on studies in other countries, long-term exposure to high arsenic levels in drinking water has caused the following health effects:  v     Thickening and discoloration of the skin. Some times these changes can lead to skin cancers. These cancers can be easily cured if discovered early. v     Stomach pain, nausea, vomiting and Diarrhea. v     Numbness in the hands and feet. Many of the health effects of arsenic exposure are often seen with other common illnesses, which makes it difficult for a doctor to recognize. If you or your family members are concerned about health problems you believe are related to arsenic in your well water, you should discuss them with your doctor. U should have well tested in your water. 8. Toxic kinetics The half-life of inorganic arsenic in blood is about 2 hours; the half-life of the methylated metabolites range from 5 to 20 hours.   Absorption  Pentavalent arsenic is well absorbed through the gut, but the trivalent form is more lipids soluble. Toxicity results from the arsenite form (As+3), especially by dermal absorption. Inhalation can result in symptomatic chronic exposure, particularly with arsine gas, which causes severe symptom by inhalation. Arsenic compounds are well absorbed parenterally within 24 hours. Distribution Arsenic initially localizes in the blood bound to globulin. Redistribution occurs within 24 hours to the liver, lungs, intestinal wall, and spleen, where arsenic binds to the sulfhydryl groups of tissue proteins. Only small amounts of arsenic penetrate the blood-brain barrier. Arsenic replaces phosphorus in the bone where it may remain for years. Within 30 hours post ingestion, arsenic deposits in the hair. Arsenic levels in hair sections may provide an indication of the time of exposure based on length from growth site. The hair of an individual who died 6 to 8 hours after ingestion of an arsenic overdose generally does not contain arsenic. Pregnancy  Inorganic arsenic crosses the placenta. A 22 year old female at 20 weeks of gestation ingested 340 mg of sodium arsenate. The initial 24 hour urinary arsenic level was 3030 mg/L. Dimercaprol was administered. Fetal heart tones were normal. A healthy infant was delivered at 36 weeks. At birth 24 hour urinary arsenic levels were <50 mg/L in the infant and <100 mg/L in the mother. Another case of maternal arsenic ingestion at 30 week gestation resulted in infant death shortly after birth. Dimercaprol appears to be the agent of choice. D penicillamine has been associated with teratogenicity. Gastrointestinal Tract  Dilation of splanchnic vessels causes sub-mucosal vesicle formation. Rupture of these vesicles leads to rice water stools and bleeding. Subsequently, a protein losing enteropathy may develop. Despite aggressive management of arsenic intoxication and a rapid decrease in blood and urine arsenic levels, neurologic defects may persist. It appears that distribution into neural tissue is rapid and may be irreversible even with chelation.   Muscle     Fatal rhabdomyolysis dysfunction has been reported after an acute arsenic over dose. Metabolic/Hepatic  Negative nitrogen balance, hepatic fatty degeneration, central necrosis and cirrhosis, antagonism of thyroid hormone .Skin Appendages Alopecia (late), brittle fingernails, Mees's lines (horizontal white lines that appear after exposed nail bed area grows to exterior). Blackfoot Disease  Blackfoot disease is a unique peripheral artery disease in an endemic area of chronic arsenicism on the southwest coast of Taiwan. Humic acid in well water may be the main cause of the disease. Platelet activation and hypercoagulability may play a role in causing this disease. Laboratory Analytic Methods  The current standard for arsenic analysis is atomic absorption spectroscopy, which measures total arsenic, does not distinguish between pentavalent, trivalent, or organic arsine. Blood Levels  The short half-life of arsenic in the blood means that blood arsenic levels are less useful than urine levels unless exposure occurred on the same day. Serum (or blood) arsenic levels are detectable only during the first 2 to 4 hours after ingestion, after which arsenic in any form is not readily detected in blood or serum. Inorganic AS+3 and AS+5 AS+3 is more toxic than AS+5. AS+3 and AS+5 are detected in the body shortly after ingestion. Monomethylarsine and dimethylarsine predominate more than 24 hours after ingestion. Urinary AS+3 and AS+5 levels present about 10 hours and return to normal in 20 hours. Urinary monomethylarsine and dimethylarsine levels peak at 40 to 60 hours and return to baseline in 6 to 20 days after ingestion. The half life of inorganic arsenic in blood is 2 hours and that of the methylated metabolites 5 to 20 hours. Serum (or blood) arsenic levels are only detectable during the first 2 to 4 hours after ingestion .Organic As Arsenobetaine and arsenocholine have a half-life of about 4 hours and are completely excreted in 1 to 2 days. Urine: No exposure-less than 25 mg/daily., Toxic levels 50 to 50,000 mg daily, .After seafood-50 to 2,000 mg daily. Hair Levels         Hair analysis for arsenic is a semireliable method for confirming chronic toxicity. It does not discriminate between externally deposited arsenic and arsenic found within the hair shaft. Fingernails Fingernail arsenic may provide an estimate of the air arsenic exposure for a worker.  9. Arsenic poses stroke risk  Contaminated water has affected people in Bangladesh Arsenic poisoning through contaminated drinking water can lead to diseased arteries, which in turn can cause heart attacks and strokes, research shows. Scientists say they have identified a link between long-term exposure to arsenic and the accelerated development of atherosclerosis or progressive narrowing and hardening of the arteries leading to the brain. The findings, published in the Journal of the American Heart Association, strongly point to arsenic and possibly other pollutants, as risk factors for blood vessel disease throughout the body.   10. Long-term health effects of exposure The health effects of ingesting arsenic-contaminated drinking-water appear                   slowly. For this reason, a more important issue than the number of patients who currently have arsenic-caused diseases in the number who will develop these diseases in the future as a result of past and continuing exposure to arsenic. Large numbers of tube wells were installed in Bangladesh approximately 5 to 20 years ago. If the population continues   drink arsenic-contaminated water, then a major increase in the number of cases of diseases caused by arsenic may be predicted. Skin lesions The latency for arsenic-caused skin lesions (i.e., the time from first exposure to manifestation of disease), in particular keratosis, is typically about 10 years. In the 1997 consultancy, it was found that the youngest individuals with skin lesions caused by arsenic were about 10 years old. Other studies have shown that skin lesions also occur in children younger than 10 years. It was also found that in adults, exposures commenced approximately 10 years before they stated the skin lesions began to appear. In some instances, the apparent latency for the appearance of skin lesions from the time of first exposure to contaminated water from the Tube well currently in use was much shorter, but as no measurements were available for water from previously used tube wells, a short latency from first exposure could not be inferred. However, latency that is shorter or longer than 10 years may occur, and the rapidity of the appearance of skin lesions appears to be dose dependent. Further studies of the latency and latterns of occurrence of skin lesions are needed and these will require careful interviewing of participants about the current and past exposures. Cancer Skin cancer. Small numbers of cases of skin cancer have started to appear. Since the typical latency is more than 20 years after the beginning of exposure, the fact that only a small number have been found provides little reassurance about the future incidence of skin cancer. A study of a large population in Taiwan found a clear dose-response relationship between arsenic concentrations in drinking-water and the prevalence of skin cancer. In this study, the average concentration of arsenic in water was about 500 ?g/l, and by age 60 more than 1 in 10 had developed skin cancer. The lifetime risk of developing skin cancer from the intake of 1 ?g. kg body weight / day (roughly equivalent to 1 litre per day at concentrations of 50 ?g/l) of arsenic in water ranges from 1 per 1000 to 2 per 1000. Though large numbers of skin cancers have been reported in Taiwan, the future burden of arsenic-caused skin cancer in Bangladesh is uncertain. Differences in susceptibility between the populations of Taiwan and Bangladesh may exist that only time and further study will identify. However, as yet there is no evidence to indicate that the long-term risks of skin cancer would be any lower in Bangladesh than in Taiwan.     Mortality from internal cancers  In other countries, the main causes of death associated with chronic ingestion of arsenic in drinking-water are internal cancers; skin cancers are not usually fatal if treated appropriately. Dramatic increases in mortality from internal concerns have been reported in Taiwan and Chile. In Taiwan, populations exposed to high concentrations of arsenic in their drinking-water, containing an average of 800 ?g/l of arsenic, had estimates of their relative risk of bladder cancer in the order of 30-60. In Region II of northern Chile, 5-10% of all deaths occurring among those over the age of 30 were attributable to arsenic caused internal cancers, in particular bladder cancer and lung cancer. Average exposures were in the order of 500 ?g/l (0.5 mg/l) over 10-20 years; exposure decreased in subsequent years after remediation efforts were introduced. Long latency was apparent, and increase in mortality continued for 40 years after the highest exposures began In Argentina, a mortality study in the arsenic-exposed region of Cordobo found increased risks of bladder and lung cancer among men and women from 1986 to 1991, although concentration were lower (average 178 ?g/l) than in Taiwan and Chile. Although specific estimates of the current and future health effects of arsenic exposure are uncertain, in the case of Bangladesh it can be inferred that since there are many people who currently have skin lesions caused by ingesting arsenic, many more cases will occur if exposure continues; based on what is known about the relationship between ingestion and the development of internal cancers, it is reasonable to expect marked increases in mortality from internal cancers once sufficient latency has been reached. Treatment  The basic treatment is to supply the patient with drinking-water that is free from arsenic. This is the first priority. Indeed, in the absence of good evidence for the effectiveness of other treatments, the second priority is to continue providing arsenic-free water, and the third priority is to monitor patients to ensure that they remain unexposed to arsenic. Providing arsenic-free water reduces the risk of further complications and disease caused by arsenic. There are no well-designed studies to show whether cessation of exposure leads to improvement in skin keratosis .Thus far, anecdotal interviews of patients suggests that mild to moderate keratosis do improve with cessation of exposure. Chelation. Some physicians have been giving chelation therapy to arsenic patients in West Bengal and Bangladesh. The objective of chelation therapy is provide the patient with a chemical to which arsenic binds strongly, and is then excreted in urine. Providing such treatment could remove large stores of arsenic from the body in a matter of hours. There are several problems with chelation therapy in cases of chronic arsenic exposure. The first is related to the observation that arsenic is excreted rapidly even without chelation therapy. Most of the readily available arsenic in the body will be excreted in the urine within 1 week. The question is whether chelation might remove arsenic which is, for example, bound in the skin and which might without chelation only be removed slowly. This is possible but exposure to arsenic generally occurs over many years, and chelation may make little difference to the cumulative dose of arsenic that patients have received. Thus, chelation therapy is unlikely to reduce the future risk of cancer. Whether it might improve keratoses more rapidly than simply stopping exposure is unknown. This idea has some plausibility but its effectiveness has not been established.      The second problem with chelation therapy is the lack of any clinical trials that found evidence of its effectiveness. When exposure to arsenic ceases, improvement in skin lesions might occur. Thus, if a patient improves after chelation therapy it could be due to the cessation of exposure alone or to both cessation and chelation therapy. (Finding that patients improve after chelation therapy does not provide evidence that the therapy) itself is effective. The third problem with chelation therapy is that it is of no benefit if the patient continues to drink contaminated water after treatment, and it may give the false impression that effects can be treated despite continued exposure. Thus, chelation therapy should not be used routinely, although careful controlled studies of chelation therapy in patients with keratoses and other arsenic effects should perhaps be undertaken Nutrition             Since evidence from Taiwan suggests that some nutritional factors may modify cancer risks associated with arsenic, it has been proposed that providing vitamins and improving nutrition may be of benefit to patients. In particular, vitamin A is known to be beneficial in the differentiation of various tissues, particularly the skin. If the doses given are not excessive, there are other nutritional benefits to providing vitamins, particularly in populations that may have inadequate levels of micronutrients. For these reasons, it is recommended that all patients with skin lesions be provided multivitamin tablets and that research projects be undertaken to establish whether or not they are effective for patients with arsenicosis Other considerations  Advanced keratosis on the palms of the hands and soles of the feet are extremely debilitating, and superimposed infections, such as fungal infections, may cause serious problems. Providing moisturizing lotions and treatment for infections may be beneficial and should be part of routine care in advanced cases. These topics should be systematically studied. Arsenic is a probable contributor to causation of diabetes mellitus. For this reason, urinary glucose should be tested in all patients with arsenicosis, and appropriate treatment and monitoring should be started if necessary. Patients' blood pressure should also be monitored since arsenic exposure may induce hypertension. 11. Arsenic in Drinking Water May Accelerate Artery Disease  Determining a new federal standard for acceptable levels of arsenic in drinking water was no easy task. Now new research adds to the list of ills caused by exposure to the element. According to a study published in Circulation: Journal of the American Heart Association, long-term exposure to arsenic in drinking water is directly related to the development of atherosclerosis in the arteries leading to the brain. Chih-Hao Wang of the National Taiwan University and colleagues studied 463 people living in an area of Taiwan with high rates of arseniasis, or chronic arsenic poisoning. Scientists have tracked the amount of arsenic in well water in the region for more than four decades. Combining these records with detailed residential and medical histories allowed the team to determine the amount of arsenic exposure for each participant. The researchers then used ultrasound to measure the amount of atherosclerotic plaque in subjects' carotid arteries, which carry blood to the brain. The team found that three indices of long-term exposure to arsenic correlated directly with the amount of atherosclerosis present in the carotid arteries. People with the highest arsenic exposure, they report, had three times the risk of atherosclerosis as seen in those who were not exposed to the element. "Our results indicate that long-term arsenic exposure may lead to the progression or acceleration of carotid artery disease and most likely generalized artery disease in humans," Wang notes. Because this study occurred in a region characterized by extremely high levels of arsenic in drinking water, the lowest level of contamination examined was 50 micrograms per liter. 12. What happens to arsenic when it enters the environment?          Arsenic occurs naturally in soil and minerals and it therefore may enter the air, water, and land from wind-blown dust and may get into water from runoff and leaching. Volcanic eruptions are another source of arsenic. Arsenic is associated with ores mined for metals, such as copper and lead, and may enter the environment during the mining and smelting of these ores. Small amounts of arsenic also may be released into the atmosphere from coal-fired power plants and incinerators because coal and waste products often contain some arsenic. Arsenic cannot be destroyed in the environment. It can only change its form, or become attached to or separated from particles. It may change its form by reacting with oxygen or other molecules present in air, water, or soil, or by the action of bacteria that live in soil or sediment. Arsenic released from power plants and other combustion processes is usually attached to very small particles. Arsenic contained in wind-borne soil is generally found in larger particles. These particles settle to the ground or are washed out of the air by rain. Arsenic that is attached to very small particles may stay in the air for many days and travel long distances. Many common arsenic compounds can dissolve in water. Thus, arsenic can get into lakes, rivers, or underground water by dissolving in rain or snow or through the discharge of industrial wastes. Some of the arsenic will stick to particles in the water or sediment on the bottom of lakes or rivers, and some will be carried along by the water. Ultimately, most arsenic ends up in the soil or sediment. Although some fish and shellfish take in arsenic, which may build up in tissues, most of this arsenic is in an organic form called arsenobetaine (commonly called "fish arsenic") that is much less harmful.  13. How can arsenic enter and leave body?            If you swallow arsenic in water, soil, or food, most of the arsenic may quickly enter into your body. The amount that enters your body will depend on how much you swallow and the kind of arsenic that you swallow. This is the most likely way for you to be exposed near a waste site. If you breathe air that contains arsenic dusts, many of the dust particles settle onto the lining of the lungs. Most of the arsenic in these particles is then taken up from the lungs into the body. You might be exposed in this way near waste sites where arsenic-contaminated soils are allowed to blow into the air, or if you work with arsenic-containing soil or products. If you get arsenic-contaminated soil or water on your skin, only a small amount will go through your skin into your body, so this is usually not of concern. If you are exposed to arsenic, your liver changes some of this to a less harmful organic form. Both inorganic and organic forms leave your body in your urine. Most of the arsenic will be gone within several days, although some will remain in your body for several months or even longer. If you are exposed to arsenic, your liver changes some of this to a less harmful organic form. Both inorganic and organic forms leave your body in your urine. Most of the arsenic will be gone within several days, although some will remain in your body for several months or even longer.   14. Arsenic in Drinking Water   ? The most common and significant route of arsenic exposure is through the ingestion of water contaminated with arsenic concentrations of greater than the Indian standard of 0.05 mg/L or the WHO recommendation of 0.01 mg/L. ? Because arsenic is colorless and odorless, it is impossible to detect by the user. ? Boiling water does not get rid of arsenic. ? Eating foods cooked in arsenic contaminated water can be a significant route of exposure, so it suggested that food be   prepared using safe water. ? Susceptibility to arsenicosis depends on the amount of contaminated water consumed, the length of time the water has been consumed, and the concentration of arsenic in the water. ? Symptoms of chronic arsenic poisoning can take years to develop and a person can drink contaminated water and not look or feel sick right away. This makes it difficult to diagnose, but some typical manifestations are shown and described here. ? Other health factors, such as malnutrition, may have a synergistic, worsening effect. ? There is no effective treatment for diseases caused by arsenic. ? Therefore, it is necessary for the complete cessation of ingesting arsenic-contaminated water. ? Arsenicosis is not contagious and people cannot contract it by touching or embracing. Water from a Protected dug well is naturally low in arsenic concentrations and is a safe, alternative source to use for drinking and cooking purposes.   How can families reduce the risk of exposure to arsenic? If your doctor finds that you have been exposed to substantial amounts of arsenic, ask whether your children might also have been exposed. Your doctor might need to ask your state health department to investigate. If you use arsenic-treated wood in home projects, personal protection from exposure to arsenic-containing sawdust may be helpful in limiting exposure of family members. These measures may include dust masks, gloves, and protective clothing. Arsenic-treated wood should never be burned in open fires, or in stoves, residential boilers, or fire places, and should not be composted or used as much. If you live in an area with a high level of arsenic in the water or soil, substituting cleaner sources of water and limiting contact with soil (for example, through use of a dense groundcover or thick lawn) would reduce family exposure to arsenic. By paying careful attention to dust and dirt control in the home (air filters, frequent cleaning), you can reduce family exposure to contaminated dirt. Some children eat a lot of dirt. You should prevent your children from eating dirt. You should discourage your children from putting objects in their mouths. Make sure they wash their hands frequently and before eating. Discourage your children from putting their hands in their mouths or engaging in other hand-to-mouth activities. Since arsenic may be found in the home as a pesticide, household chemicals containing arsenic should be stored out of reach of young children to prevent accidental poisonings. Always store household chemicals in their original labeled containers; never store household chemicals in containers that children would find attractive to eat or drink from, such as old soda bottles. Keep your Poison Control Center's number by the phone. It is sometimes possible to carry arsenic from work on your clothing, skin, hair, tools, or other objects removed from the workplace. This is particularly likely if you work in the fertilizer, pesticide, glass, or copper/lead smelting industries. You may contaminate your car, home, or other locations outside work where children might be exposed to arsenic. You should know about this possibility if you work with arsenic. Your occupational health and safety officer at work can and should tell you whether chemicals you work with are dangerous and likely to be carried home on your clothes, body, or tools and whether you should be showering and changing clothes before you leave work, storing your street clothes in a separate area of the workplace, or laundering your work clothes at home separately from other clothes. Material safety data sheets (MSDS) for many chemicals used should be found at your place of work, as required by the Occupational Safety and Health Administration (OSHA) in the U.S. Department of Labor. MSDS information should include chemical names and hazardous ingredients, and important properties, such as fire and explosion data, potential health effects, how you get the chemical(s) in your body, how to properly handle the materials, and what to do in the case of emergencies. Your employer is legally responsible for providing a safe workplace and should freely answer your questions about hazardous chemicals. Your state OSHA-approved occupational safety and health program or OSHA can answer any further questions and help your employer identify and correct problems with hazardous substances. Your state OSHA-approved occupational safety and health program or OSHA will listen to your formal complaints about workplace health hazards and inspect your workplace when necessary. Employees have a right to seek safety and health on the job without fear of punishment. 16. Is there a medical test to determine whether I have been exposed to arsenic?  Several sensitive and specific tests can measure arsenic in your blood, urine, hair, or fingernails, and these tests are often helpful in determining if you have been exposed to above-average levels of arsenic in the past. These tests are not usually performed in a doctor's office. They require sending the sample to a testing laboratory. Measurement of arsenic in your urine is the most reliable means of detecting arsenic exposures that you experienced within the last several days. Most tests measure the total amount of arsenic present in your urine. This can sometimes be misleading, because the no harmful forms of arsenic in fish and shellfish can give a high reading even if you have not been exposed to a toxic form of arsenic. For this reason, laboratories sometimes use a more complicated test to separate "fish arsenic" from other forms. Because most arsenic leaves your body within a few days, analysis of your urine cannot detect if you were exposed to arsenic in the past. Tests of your hair or fingernails can tell if you were exposed to high levels over the past 6-12 months, but these tests are not very useful in detecting low-level exposures. If high levels of arsenic are detected, this shows that you have been exposed, but unless more is known about when you were exposed and for how long, it is usually not possible to predict whether you will have any harmful health effects.   17. What recommendations has the federal government made to protect human health?   The federal government develops regulations and recommendations to protect public health. Regulations can be enforced by law. The EPA, the Occupational Safety and Health Administration (OSHA), and the Food and Drug Administration (FDA) are some federal agencies that develop regulations for toxic substances. Recommendations provide valuable guidelines to protect public health, but cannot be enforced by law. The Agency for Toxic Substances and Disease Registry (ATSDR) and the National Institute for Occupational Safety and Health (NIOSH) are two federal organizations that develop recommendations for toxic substances. Regulations and recommendations can be expressed as "not-to-exceed" levels, that is, levels of a toxic substance in air, water, soil, or food that do not exceed a critical value that is usually based on levels that affect animals; they are then adjusted to levels that will help protect humans. Sometimes these not-to-exceed levels differ among federal organizations because they used different exposure times (an 8-hour workday or a 24-hour day), different animal studies, or other factors. Recommendations and regulations are also updated periodically as more information becomes available. For the most current information, check with the federal agency or organization that provides it. Some regulations and recommendations for arsenic include the following: The federal government has taken several steps to protect humans from arsenic. First, EPA has set limits on the amount of arsenic that industrial sources can release into the environment. Second, EPA has restricted or canceled many of the uses of arsenic in pesticides and is considering further restrictions. Third, in January 2001, the EPA lowered the limit for arsenic in drinking water from 50 to 10 ppb. Finally, OSHA has established a permissible exposure limit (PEL), 8-hour time-weighted average, of 10 ?g/m3 for airborne arsenic in various workplaces that use inorganic arsenic. 18. Treatment Options and Technologies Avoidance is the best policy                The best way to avoid arsenic poisoning is not to drink water that contains arsenic. For community water supplies, it may be possible and more economical to switch to a water source that is lower in arsenic rather than trying to remove arsenic from water. Usually surface water sources are lower in arsenic than groundwater, but they have to be treated to remove disease-causing microorganisms. Not all groundwater is high in arsenic. Even in places where the arsenic levels are high, the concentration seems to be patchy. The reasons for this are not known, but choosing a new location for a well can help.  When all else fails, treat the water Unfortunately, if you have your own well, you have no choice but to use the water under your property. Some communities may only have access to water that is high in arsenic as well. In these cases, the water must be treated to remove the arsenic. The requirements for treatment are different for private wells and public water supplies. We use water for many purposes, and they don't all have to be treated to the same degree. There's not much health risk associated with watering your lawn with water that contains arsenic. On the other hand, you don't want your drinking water to contain arsenic! Public water supplies have to remove the arsenic from all of the water, since there is a single pipe that takes the water from the treatment facility to homes. The water district has no control over the end uses of water, so they can?t treat only that portion of the water that will be used for drinking and food preparation. That means that all of the water used for showering, washing dishes, clothes and cars, watering the lawn and any other use must be treated, even though they pose little risk to consumers. Every treatment step costs money. In areas like cities, where people live close to one another, there are many people that can all contribute to the cost of building and running the treatment facility, and the economy is good, it is usually feasible to treat the water. That?s the case for cities in the United States. In some developing countries, the cost of central treatment of city water is still too high. In most rural areas worldwide (including the US), central treatment of the water supply is too expensive. 18. Treatment of public water supplies  For public water supplies, the main methods of treatment are precipitation, adsorption or ion exchange. Chemical precipitation (as opposed to rain or snow) occurs when the concentration of a salt in solution is higher than its solubility limit. Crystals begin to form and the chemical ?crashes? out of solution.  You can see this around the lid of a bottle of maple syrup, for example. The liquid syrup around the lid when you close the bottle evaporates until the sugar concentration is too high to stay in solution. It crystallizes forming the maple sugar that makes the bottle so hard to open next time   Well, other chemicals can precipitate, too. Some chemicals are not very soluble at all, and they will precipitate even when the concentration in water is very low. In water treatment, you can add chemicals to the water that are not soluble when the ion you want to remove is present. For example, to remove calcium (Ca2+), which contributes to hardness, you can add soda ash, Na2CO3. Calcium carbonate (CaCO3) is not soluble in water, so the calcium ions and carbonate ions precipitate to form solid calcium carbonate, which can be filtered out of the water. When these kinds of reactions occur, you can also get the removal of other ions which get stuck in the solid lattice that is created as the salts precipitate, or they may get trapped as the precipitate settles out.  If the aim is to remove a compound that is difficult to precipitate, like arsenic, you have to rely on trapping to remove them by precipitation. Iron is often added to help remove other contaminates from water. Other metals bind to the iron as it forms a precipitate with hydroxide ions. The whole schemers can then be removed from the water by settling and or filtration. In chemical precipitation, the water starts to look cloudy as the chemicals start to crash out of solution. After a while they begin to settle out to the bottom, as seen in the beaker on the right.      Adsorption is when a chemical sticks to a surface. The surface has to have free binding sites for the chemical to attach to, and obviously the binding sites have to be attractive to the chemical you?re trying to remove. A commonly used adsorbent (the surface that the chemical sticks to) is activated carbon. That?s what is in many filtration systems that you can put in the refrigerator. Unfortunately, activated carbon is not much good for arsenic. Arsenic will adsorb to the surfaces of sorbets like alumina (aluminum based the picture shows how chemicals stick to charcoal or activated carbon. The large blue circles are the activated carbon particles (adsorbent). Notice how there is many more of the orange adsorbate molecules on the charcoal than in the water. That means activated carbon is an effective adsorbent for the orange compound adsorbent) and iron or iron oxides                                               . Ion exchange is where you have a solid material or resin with a lot of charged binding sites. These sites are occupied by ions with the opposite charge (counter-ions). As you pass water over these surfaces, ions in solution can kick off the counter-ions and bind to the ion exchange sites, if they are more attracted to the site than the original counter-ion. That?s where the exchange part of the name comes in ? the ion you want to remove is exchanged for the counter-ion which ends up in the water. To remove arsenic from solution by ion exchange, the arsenic must be in a charged form As(V) at near neutral pH will have a negative charge), and it must displace the counter-ions on the ion exchange resin (the solid). In the picture, the ion exchanger is trading sodium counter ions (gray dots) for calcium and magnesium (green triangles and squares). This is a water softening scenario. The water at the top of the column has a lot of green squares and triangles (magnesium and calcium). These displace the gray sodium dots on the resin beads releasing the sodium so that the water coming out has only sodium.  For arsenic treatment you would need an anion exchanger, where the counter-ion is negatively charged. Chloride or hydroxyl ions are typical counter-ions.                     18. Treatment of household water supplies For home use, treatment options need to be simple, relatively fail-safe and require little maintenance, since most of us don?t have the time or expertise to constantly tinker with the water system. It is also possible to limit water treatment to the water that is to be used for drinking water and food preparation because exposure through skin contact with water is very low. This is much less expensive than treating all of the water entering the home. Systems that are available for homes include adsorption/ion exchange units and reverse osmosis units. Chemical precipitation is too tricky for home use, and you would have to deal with the buildup of solids (called sludge).  Reverse osmosis is when you apply pressure to the water on one side of a membrane that does not allow charged molecules to pass through. The membrane prevents the passage of ions, so the water that passes through to the collection side of the membrane is stripped of ions, like As (V). The trouble is, small, uncharged molecules like As (III) will pass through the membrane, so the effectiveness of the system depends on the form of the arsenic present in the water. Normally osmosis pushes water through a membrane (that doesn't allow ions to pass) from an area of low ion concentration to an area of high ion concentration. The pressure is needed in this system to reverse the direction of water Flow Individual homeowners can also treat all of the water that they use rather than only the drinking water, but the cost of such units is usually high (thousands), plus maintenance costs 19.  Prevention, management, and future directions.  The human tragedy due to arsenic toxicity is most acute in the developing world where in countries such as Bangladesh the lives of millions of people are affected. In solving the increasing problem of arsenic contamination and ill health, many issues need to be clarified. Information is required to determine if there is a threshold for carcinogenic effects to manifest and also to define the dose and duration of exposure. Studies are required to link toxic manifestations with possible genetic polymorphism, age, gender, nutritional status, and the protective role of vitamins, minerals, and antioxidants. There is a marked variation in clinical features among individuals in the same household as is commonly seen in Bangladesh. This may be due to "slow" or "fast" methylators of arsenic similar to patients with inflammatory bowel disease who are "slow" or "fast" acetylators who therefore respond differently to treatment with salicylate. The provision of safe drinking water is a priority. A variety of methods of diverse complexity are available to remove arsenic from drinking water. The methodology, especially in developing countries, that is urgently required should be affordable, sustainable by the population, and cost effective. Among the methods available for removing arsenic from water are processes of precipitation or ion exchange. Filtration of arsenic from tube wells has spawned a range of filters of varying sophistication and cost and issues of affordability, efficiency, and maintenance are linked with their use. Importantly, the process and cost of disposing the arsenic sequestered after filtration needs careful consideration. Promising studies are reported using iron treated natural materials such as iron treated activated carbon, iron treated gel beads, and iron oxide coated sand, and of these iron oxide coated sand was the most effective compound. The Stevens technology for arsenic removal is inexpensive and involves mixing a small packet of powder containing iron sulphate and calcium hypochlorite in a large bucket of water, which is then filtered through several cm of sand. One attractive and inexpensive option that is widely available is to harvest rain water and harness surface water. In Bangladesh the volume of water that flows into the Bay of Bengal is second only to that flowing into the Amazon basin. Bangladesh has an annual rainfall of 1500?2000 mm with eastern areas of the country receiving 3500 mm. The option of harnessing this natural wealth of Bangladesh has received, from available published data, insufficient attention. However, the cheapest solution would depend on community goodwill encouraging the use of a neighbour?s well (well sharing) that is not contaminated. More than 90% of people in Bangladesh live within 200 m of a clean, safe source of well water.  No treatment of proven benefit is currently available to treat chronic arsenic toxicity. Treatment options advocated are vitamin and mineral supplements and antioxidant therapy. The benefits of these treatment measures need to be evidence based to receive endorsement and wider application. At a cellular level, in view of the apoptotic mechanism of action of arsenic, the effects, especially of antioxidants are theoretically of value. However the benefits of these compounds at cellular level need validation in human subjects with chronic arsenic toxicity. At present, in chronic poisoning, therapy is limited to supportive measures. 20. Where is arsenic a problem?   The following is a list of countries that have identified areas of high arsenic in their water resources. Some are naturally occurring in groundwater, some come from geothermal sources (such as hot springs) and some are affected by mining. Countries that are not listed may have problems that have either not yet been recognized, or have not been reported in the literature that I have read. Argentina                                              Laos Mexico Myanmar Nepal Chile China Germany Ghana  Austria Australia Bangladesh Cambodia Canada Hungary India Inner Mongolia Iran Jamaica Japan   The magnitude of the problem in Bangladesh brought this issue to worldwide attention. According to some estimates, arsenic in drinking water will cause 200,000 ? 270,000 deaths from cancer in that country alone.  Let?s look at the situation in Bangladesh. About 30,000,000 people are estimated to be consuming arsenic contaminated drinking water (>50 ppb or mg/L) in that country. This is a huge public health disaster. Way bigger than any other environmental catastrophe. And worst of all, it happened because people were trying to make the water safer to drink there!  Many people in developing nations die every year due to illnesses spread by water. Diseases like cholera, typhoid, diarrhea and many others kill millions of people each year. To decrease the incidence of disease in Bangladesh about 30 years ago, aid agencies, and later private companies, started replacing shallow dug wells that were contaminated with surface water (and bacteria from fecal material) with deeper bedrock wells. Unfortunately, due to the geological formations in the area, the wells in many regions had high arsenic levels. It was not until the 1990s that the medical problems there were finally linked to the water.  Taiwan is another area that has been very hard-hit by arsenic poisoning through drinking water. 21. Contamination of drinking-water by arsenic in Bangladesh: a public health emergency  IN Bangladesh, arsenic contamination of water in tubewells was confirmed in 1993 in the Nawabganj district.testing was done in the following years; this included investigations by the Department of Occupational and Environmental Health of the National Institute of Preventive and Social Medicine. Results from various Laboratories were collated in a WHO country situation report in 1996. The institutions that provided results included the Jadavpur University in Calcutta, India, the Bangladesh Atomic Energy Commission, the Department of Public Health Engineering's laboratories in the Khulnaand Rajshahi districts, and the National Institute of Preventive and Social Medicine in Dhaka. Altogether, 400measurements were presented in the report, although contamination in some wells was measured by more than one laboratory. In about half of the measurements concentrations were above 50g/1, which is clearly in excess of the maximum level recommended by WHO of 10?g/1 and greater than the maximum level of 50?g/1 permitt in Bangladesh.To raise awareness of the seriousness of the arsenic problem in West Bengal and to draw attention to the need forstudies in Bangladesh, a conference was convened in 1995 by D Chakraborti and the School of Environmental Studiesof Jadavpur University in Calcutta. In the years after the conference, the extent of the problem in Bangladesh has become clearer through additional surveys of the water and population, many of which were led by ChakrabortiA study conducted in the Rajarampur village of the Nawabganj district, by the National Institute of Preventive and Social Medicine and the School of Environmental Studies, found that 29% of the 294 tube-wells tested had arsenic concentrations greater than 50g/1. Between September 1996 and June 1997, a survey was jointly conducted by Dhaka Community Hospital and the School of Environmental Studies. An examination of 265 wells in Samta village in the Jessore district found that about 91% of the wells had arsenic concentrations higher than 50g/1 . In 1998, a British Geological Survey of 41 districts collected 2022 water samples 35% were found to have arsenic concentrations above 50g/1 and 8.4% were above 300g/1 was about 21 million. This number would be approximately doubled if WHO's standard of 10 g/1 were adopted. Further studies conducted by the School of Environmental Studies and the Dhaka Community Hospital found that 59% of the 7800 groundwater samples had arsenic concentrations greater than 50?g/1.  Surveys of the effects on the population's health have occurred concurrently with the previous studies of groundwater contamination. From December 1996 to January 1997, a three-week survey was conducted by the Dhaka Community Hospital and the School of Environmental Studies. The survey team visited 18 affected districts. Of the 1630 adults and children examined, 57.5% of them had skin lesions due to arsenic poisoning. In another study, approximately one-third of the 7364 patients examined had skin lesions due to arsenic. The population of the 42 affected districts was 76.9 million. These studies do not imply that the entire population is drinking contaminated water. A recent report from the World Bank has estimated that 20 million inhabitants of Bangladesh may be drinking arsenic-contaminated water. The actual extent of the contamination and the number of people with skin diseases caused by arsenic might be many times higher than is currently estimated. For comparison, it has been estimated that in West Bengal the number of people exposed to arsenic is 1.5 million, and one estimate of the number of patients with arsenicosis exceeds 200 000. Since the estimate of those who may be drinking arsenic-contaminated water in Bangladesh is in the tens of millions, it is reasonable to expect the unless exposure ends the number of people with arsenicosis will eventually far exceed the number observed in West Bengal. Although all wells and all villagers have not been systematically tested and examined, this should not delay action. The evidence that has accumulated since 1997 has only confirmed that this is a public health threat of great magnitude Concentration of Arsenic in Shallow and Deep Aquifer Wells in Bangladesh Southern Bangladesh Khulna Division Shallow Aquifers Max. Conc. AS mg/l (St. 0.05mg/l) % of Contaminated wells Deep Wells > 200 m Fakirhat 1.00 40% 0% Chuadanga 0.841 35% 0% Khulna Metro 0.500 13% 0% Batighata 0.280 11% 0% Dghalia 0.430 18% 0% Rupsha 0.650 32% 0% Shalikhira 0.120 40% 0% Bagerhat 0.160 44% 0% Source: British Geological Survey and MML U.K, 1999 World Bank Involvement in Ground water Withdrawal Activities: Project Name BRD/IDA at Board* USD $ Million Approval Date Project Status Shallow Tube well and Low Lift Pump Irrigation Development Project 75 30. 05. 91 Closed Deep Tube wells Project (02) 68 10. 08. 82 Closed Hand Tube wells Project 18 5. 07. 81 Closed Low Lift Pumps Project 37 11. 03. 80 Closed Shallow Tube wells Project 16 16. 06. 77 Closed East Pakistan Tube wells Project 16 23. 06. 70 Closed Total 228         22. Arsenic Problem in Nepal   There have been many investigations and recommendations by international scientists that the drinking water derived from the groundwater - the aquifers - in Nepal, shows similar characteristics to those of the Bengal Basin, the Gangetic floods plains and the areas adjoining West Bengal. The Terai belt of Nepal  lies close to these areas and recently the same problem has been discovered in the groundwater of Nepal .Department for Water, Sanitation and Sewage (DWSS) initiated the Arsenic investigations in Nepal in year 2000, by measuring 268 drinking water samples in Terai, where the Arsenic Contamination is highest. This investigation was done in Eastern Terai in the districts Jhapa, Morang & Sunsari. The data revealed that some ground water samples from the areas was contaminated with arsenic. The report showed that about 9 % of the total analyzed samples exceeded the WHO guideline value of 10 μg/l and the maximum concentration of arsenic was found to be 75 μg/l. Nepal Red Cross Society (NRCS) supported by the Japanese Red Cross (JRCS) soon followed up in May 2000 and have so far been the leading stakeholder in Nepal in the measuring of the Arsenic crisis, having measured more than 12,000 (Confirm) samples using an Atomic Absorption Spectrophotometer (AAS). This expensive but accurate measuring method can only be done in well equipped laboratories, which at present only are available in Kathmandu. This method raises the question of conserving the samples days or weeks. Conservation of samples from the field. Page 42.Today where an adequate and systematic monitoring programme for arsenic in groundwater in Nepal is the process of being carried out, and as around 17.000 wells have been measured, it is a well known fact that different Arsenic poisonous compounds are released into the groundwater, which is consumed by the largely unaware Nepali population. Percentage of Affected Wells in Nepal  On the basis of approximately 17,000 data sets collected and measured in Nepal by concerned stakeholders. Cf. Table 3, page 31, and partly processed by NEWAH, it can be estimated that a minimum of 30 % of all installed tube wells have arsenic levels above 10 ?g/l. A minimum of 5 % have serious long-term health damaging concentrations of  over  50 ?g/l. Percentage goes up as more and more wells are measured. The latest two years (2000-2002) intensified measuring gives rise to severe concern for another reason. Having participated actively and followed the debates and papers released from the Nepali stakeholders for the last two years, it seems that the percentage of the infected wells have increased over time. In year 2000 the percentages of tube wells above 10 and 50 ?g/l was 17 and 2 % respectively. At that time approximately 1500 wells had been measured. It seems that the more the different stakeholders co-operate to measure, the higher these percentages becomes. Naturally this might also be an effect of an increased knowledge among the stakeholders, where the Arsenic problems are most severe, and that we in a co-operation naturally try to measure the highest risk areas first. Hence the precise percentages in Nepal should today be regarded as relatively unknown, but as can be seen from the figure a guess on 5 % above  50 ?g/l, and that 30 % of all tube wells in Nepal are above 10 ?g/l seems reasonably. Only when all wells, private, public and others have been measured these figures will be known more precisely. Never exactly, since the concentration in each well varies with season, pumped water prior to sampling, measuring method, conservation method etc. Variation with Depth of Tube Well in nepal  Furthermore a variation with the amount of water pumped prior to sampling is also to be expected, since this is an indication of the Arsenic concentration variation with depth of pumped up groundwater. The exact relationship between pump strokes prior to sampling and precise ground water depth will be difficult to determine, as different pumps are not constructed the same way. In Nawalparasi district NEWAH measured one well, which was said to pump water from 25 feet below to 10-50 ?g/l total Arsenic. The neighbouring well 5 meters apart drew water from 65 feet down and showed a concentration of app. 300 ?g/l. The depth of the two wells was not verified.         Conclusion Arsenic pollution is now a global concern. With advancement of civilization, our beloved world becomes more and more polluted by various sources including arsenic, rendering itself more and more hazardous for our life. Research work on the heavy metal   arsenic   pollution is highly limited in Bangladesh Around 30 million people of Bangladesh is exposed to the wide spread arsenic  contaminated  drinking water which causes arsenicosis. To date there are  no widely  accepted  criteria for diagnosing and staging arsenicosis , no established treatment other than stopping the exposure to the source  of poisoning. Considering the potential magnitude of the arsenic health crisis  the current lack of critical   epidemiological and clinical information and public regarding  the importance and ways of addressing the issue with due emphasis and attention.  The arsenic related interventions in the sector will include behavioral change communications capacity building for research and case management .For solving arsenic exposure & its health effects the following recommendation should be followed To  make  our people  aware of the curse  of arsenic poisoning and to take appropriate  measures timely the concerned authorities should come forward with their systematic mind and their helping hands. To solve the acute problem of arsenic pollution or arsenic poisoning , more research works should be undertaken to know all about its corrosive effects .Seminars , workshops, training programmers should be conducted to get detail information of arsenic poisoning.   Information centers and water testing centre should be established to make sure supply of pure drinking water. This is very important factors in this respect and also at the same time public consciousness should be awakened to make these attemped successful for solving this acute problem of serious arsenic poising in Bangladesh.  Therefore a comprehensive plan for efficient solution of the existing problem must be formulated urgently after elaborate consideration of the issues involved.                 References: Chitrakar, R. L. and Neku, A. (December 2001). http://groups.yahoo.com/group/arsenic-source/files/Nepal-Chitrakar-Neku-Scen. Elizabeth, M. Jones., (December 2000). An Overview of the Arsenic in Bangladesh. Jessica J. Hurd (June 2001). Evaluation of Three Arsenic Removal Technologies in Nepal. Submitted to the department of civil and environmental engineering in partial fulfilment of the requirements for the degree of Master Of Engineering in Civil and Environmental Engineering at the Massachusetts Institute Of Technology. Munir, A.K.M., Rasul, S.B., Habibuddowla, M., Alauddin, M. Hussam, A., and Khan, A.H. (May 2001). Evaluation of Performance of Sono 3-Kolshi Filter for Arsenic Removal from Groundwater Using Zero Valent Iron through Laboratory and Field Studies. In: Technologies for Arsenic Removal from Drinking Water, Eds. M. Feroz Ahmed, M. Ashraf Ali, and Zafar Adeel, p171-189Preprints of BUET ? UNU International Workshop, Dhaka, Bangladesh. Nepal?s Interim Arsenic Policy Preparation Report (May 2001). Sharma, R.M., (1999). Research study on possible contamination of groundwater with Arsenic in Jhapa, Morang, and Sunsari districts of Eastern Terai of Nepal. Tandukar, N., Bhattacharya, P., and Mukherjee, A.B. (November 2001). Preliminary Assessment of Arsenic Contamination in Groundwater in Nepal.
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