Arsenic contamination in groundwater: a global perspective with emphasis on the Asian scenario.

The incidence of high concentrations of arsenic in drinking-water has emerged as a major public-health problem. With newer-affected sites discovered during the last decade, a significant change has been observed in the global scenario of arsenic contamination, especially in Asian countries. This communication presents an overview of the current scenario of arsenic contamination in countries across the globe with an emphasis on Asia. Along with the present situation in severely-affected countries in Asia, such as Bangladesh, India, and China, recent instances from Pakistan, Myanmar, Afghanistan, Cambodia, etc. are presented.

Fate of over 480 million inhabitants living in arsenic and fluoride endemic Indian districts: Magnitude, health, socio-economic effects and mitigation approaches.

During our last 27 years of field survey in India, we have studied the magnitude of groundwater arsenic and fluoride contamination and its resulting health effects from numerous states. India is the worst groundwater fluoride and arsenic affected country in the world. Fluoride results the most prevalent groundwater related diseases in India. Out of a total 29 states in India, groundwater of 20 states is fluoride affected. Total population of fluoride endemic 201 districts of India is 411 million (40% of Indian population) and more than 66 million people are estimated to be suffering from fluorosis including 6 million children below 14 years of age. Fluoride may cause a crippling disease. In 6 states of the Ganga-Brahmaputra Plain (GB-Plain), 70.4 million people are potentially at risk from groundwater arsenic toxicity. Three additional states in the non GB-Plain are mildly arsenic affected. For arsenic with substantial cumulative exposure can aggravate the risk of cancers along with various other diseases. Clinical effects of fluoride includes abnormal tooth enamel in children; adults had joint pain and deformity of the limbs, spine etc. The affected population chronically exposed to arsenic and fluoride from groundwater is in danger and there is no available medicine for those suffering from the toxicity. Arsenic and fluoride safe water and nutritious food are suggested to prevent further aggravation of toxicity. The World Health Organization (WHO) points out that social problems arising from arsenic and fluoride toxicity eventually create pressure on the economy of the affected areas. In arsenic and fluoride affected areas in India, crisis is not always having too little safe water to satisfy our need, it is the crisis of managing the water.

Status of groundwater arsenic contamination and human suffering in a Gram Panchayet (cluster of villages) in Murshidabad, one of the nine arsenic affected districts in West Bengal, India.

A detailed study was carried out in a cluster of villages known as Sagarpara Gram Panchayet (GP), covering an area of 20 km2 and population of 24,419 to determine the status of groundwater arsenic contamination and related health effects. The arsenic analysis of all hand tubewells (n = 565) in working condition showed, 86.2% and 58.8% of them had arsenic above 10, and 50 microgl(-1), respectively. The groundwater samples from all 21 villages in Sagarpara GP contained arsenic above 50 microgl(-1). In our preliminary clinical survey across the 21 villages, 3,302 villagers were examined and 679 among them (20.6%) were registered with arsenical skin lesions. A total of 850 biological samples (hair, nail and urine) were analysed from the affected villages and, on average, 85% of them contained arsenic above the normal level. Thus, many people of Sagarpara might be sub-clinically affected. Our data was compared with the international one to estimate population in Sagarpara GP at risk from arsenical skin lesions and cancer. Proper watershed management and economical utilization of available surface water resources along with the villagers' participation is urgently required to combat the present arsenic crisis.

The magnitude of arsenic contamination in groundwater and its health effects to the inhabitants of the Jalangi--one of the 85 arsenic affected blocks in West Bengal, India.

To better understand the magnitude of arsenic contamination in groundwater and its effects on human beings, a detailed study was carried out in Jalangi, one of the 85 arsenic affected blocks in West Bengal, India. Jalangi block is approximately 122 km2 in size and has a population of 215538. Of the 1916 water samples analyzed (about 31% of the total hand tubewells) from the Jalangi block, 77.8% were found to have arsenic above 10 microg l(-1) [the World Health Organization (WHO)-recommended level of arsenic in drinking water], 51% had arsenic above 50 microg l(-1) (the Indian standard of permissible limit of arsenic in drinking water) and 17% had arsenic at above 300 microg l(-1) (the concentration predicting overt arsenical skin lesions). From our preliminary medical screening, 1488 of the 7221 people examined in the 44 villages of Jalangi block exhibit definite arsenical skin lesions. An estimation of probable population that may suffer from arsenical skin lesions and cancer in the Jalangi block has been evaluated comparing along with international data. A total of 1600 biologic samples including hair, nail and urine have been analyzed from the affected villages of Jalangi block and on an average 88% of the biologic samples contain arsenic above the normal level. Thus, a vast population of the block may have arsenic body burden. Cases of Bowen's disease and cancer have been identified among adults who also show arsenical skin lesions and children in this block are also seriously affected. Obstetric examinations were also carried out in this block.

Murshidabad--one of the nine groundwater arsenic-affected districts of West Bengal, India. Part I: magnitude of contamination and population at risk.

INTRODUCTION: To understand the severity of the arsenic crisis in West Bengal, India, a detailed, 3-year study was undertaken in Murshidabad, one of the nine arsenic-affected districts in West Bengal. The district covers an area of 5324 km2 with a population of 5.3 million. METHODS: Hand tubewell water samples and biologic samples were collected from Murshidabad and analyzed for arsenic by FI-HG-AAS method. Inter laboratory analysis and analyses of standards were undertaken for quality assurance. RESULTS: During our survey we analyzed 29,612 hand tubewell water samples for arsenic from both contaminated and non-contaminated areas, and 26% of the tubewells were found to have arsenic above 50 microg/L while 53.8% had arsenic above 10 microg/L. Of the 26 blocks in Murshidabad, 24 were found to have arsenic above 50 microg/L. Based on our generated data we estimated that approximately 0.2 million hand tubewells are installed in all 26 blocks of Murshidabad and 1.8 million in nine arsenic-affected districts of West Bengal. It was estimated on the basis of our data that about 2.5 million and 1.2 million people were drinking arsenic-contaminated water with concentrations above 10 and 50 microg/L levels respectively in this district. The analysis of total 3800 biologic (nail, urine, and hair) samples from arsenic-affected villages revealed that 95% of the nail and 94% of the urine samples contained arsenic above the normal levels and 75% of the hair samples were found to have arsenic above the toxic level. Thus, many villagers in the affected areas of Murshidabad might be subclinically affected. DISCUSSION AND CONCLUSION: Comparing our extrapolated data with international dose response results, we estimated how many people may suffer from arsenical skin lesions and cancer. Finally, if the exposed population is provided safe water, better nutrition, and proper awareness about the arsenic problem, lives can be saved and countless suffering of the affected population can be avoided.

Murshidabad--one of the nine groundwater arsenic-affected districts of West Bengal, India. Part II: dermatological, neurological, and obstetric findings.

INTRODUCTION: To understand the severity of related health effects of chronic arsenic exposure in West Bengal, a detailed 3-year study was carried out in Murshidabad, one of the nine arsenic-affected districts in West Bengal. METHODS: We screened 25,274 people from 139 arsenic-affected villages in Murshidabad to identify patients suffering from chronic arsenic toxicity for evidence of multisystemic features and collected biological samples such as head hair, nail, and spot urine from the patients along with the tubewell water they were consuming. RESULTS: Out of 25,274 people screened, 4813 (19%) were registered with arsenical skin lesions. A case series involving arsenical skin lesions resulting in cancer and gangrene were noted during this study. Representative histopathological pictures of skin biopsy of different types of lesions were also presented. Out of 2595 children we examined for arsenical skin lesions, 122 (4%) were registered with arsenical skin lesions, melanosis with or without keratosis. Different clinical and electrophysiological neurological features were noticed among the arsenic-affected villagers. Both the arsenic content in the drinking water and duration of exposure may be responsible in increasing the susceptibility of pregnant women to spontaneous abortions, stillbirths, preterm births, low birth weights, and neonatal deaths. Some additional multisystemic features such as weakness and lethargy, chronic respiratory problems, gastrointestinal symptoms, and anemia were also recorded in the affected population. DISCUSSION: The findings from this survey on different health effects of arsenic exposure were compared to those from previous studies carried out on arsenic-affected populations in India and Bangladesh as well as other affected countries. CONCLUSION: Multisystemic disorders, including dermal effects, neurological complications, and adverse obstetric outcomes, were observed to be associated with chronic arsenic exposure in the study population in Murshidabad, West Bengal. The magnitude of severity was related to the concentration of arsenic in water as well as duration of the exposure.

Arsenic groundwater contamination in Middle Ganga Plain, Bihar, India: a future danger?

The pandemic of arsenic poisoning due to contaminated groundwater in West Bengal, India, and all of Bangladesh has been thought to be limited to the Ganges Delta (the Lower Ganga Plain), despite early survey reports of arsenic contamination in groundwater in the Union Territory of Chandigarh and its surroundings in the northwestern Upper Ganga Plain and recent findings in the Terai area of Nepal. Anecdotal reports of arsenical skin lesions in villagers led us to evaluate arsenic exposure and sequelae in the Semria Ojha Patti village in the Middle Ganga Plain, Bihar, where tube wells replaced dug wells about 20 years ago. Analyses of the arsenic content of 206 tube wells (95% of the total) showed that 56.8% exceeded arsenic concentrations of 50 micro g/L, with 19.9% > 300 micro g/L, the concentration predicting overt arsenical skin lesions. On medical examination of a self-selected sample of 550 (390 adults and 160 children), 13% of the adults and 6.3% of the children had typical skin lesions, an unusually high involvement for children, except in extreme exposures combined with malnutrition. The urine, hair, and nail concentrations of arsenic correlated significantly (r = 0.72-0.77) with drinking water arsenic concentrations up to 1,654 micro g/L. On neurologic examination, arsenic-typical neuropathy was diagnosed in 63% of the adults, a prevalence previously seen only in severe, subacute exposures. We also observed an apparent increase in fetal loss and premature delivery in the women with the highest concentrations of arsenic in their drinking water. The possibility of contaminated groundwater at other sites in the Middle and Upper Ganga Plain merits investigation.

Ineffectiveness and poor reliability of arsenic removal plants in West Bengal, India.

In the recent past, arsenic contamination in groundwater has emerged as an epidemic in different Asian countries, such as Bangladesh, India, and China. Arsenic removal plants (ARP) are one possible option to provide arsenic-safe drinking water. This paper evaluates the efficiency of ARP projects in removing arsenic and iron from raw groundwater, on the basis of our 2-year-long study covering 18 ARPs from 11 manufacturers, both from home and abroad, installed in an arsenic affected area of West Bengal, India, known as the Technology Park Project (TP project). Immediately after installation of ARPs on August 29, 2001, the villagers began using filtered water for drinking and cooking, even though our first analysis on September 13, 2001 found that 10 of 13 ARPs failed to remove arsenic below the WHO provisional guideline value (10 microg/L), while six plants could not achieve the Indian Standard value (50 microg/L). The highest concentration of arsenic in filtered water was observed to be 364 microg/L. Our 2-year study showed that none of the ARPs could maintain arsenic in filtered water below the WHO provisional guideline value and only two could meet the Indian standard value (50 microg/L) throughout. Standard statistical techniques showed that ARPs from the same manufacturers were not equally efficient. Efficiency of the ARPs was evaluated on the basis of point and interval estimates of the proportion of failure. During the study period almost all the ARPs have undergone minor or major modifications to improve their performance, and after our study, 15 (78%) out of 18 ARPs were no longer in use. In this study, we also analyzed urine samples from villagers in the TP project area and found that 82% of the samples contained arsenic above the normal limit.

Arsenic contamination of groundwater and its health impact on residents in a village in West Bengal, India.

An in-depth study was carried out in Rajapur, an arsenic-affected village in West Bengal, India, to determine the degree of groundwater contamination with arsenic and the impact of this contamination on residents. The flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS) method was used to measure arsenic concentrations in water and biological samples. Dermatologists recorded the dermatological features of arsenicosis. Out of a total of 336 hand-pumped tube-wells in Rajapur, 91% (307/336) contained arsenic at concentrations > 10 microg/l, and 63% (213/336) contained arsenic at > 50 microg/l. The type of arsenic in groundwater, the variation in concentrations of arsenic as the depth of tube-wells changed, and the iron concentration in the wells were also measured. Altogether 825 of 3500 residents were examined for skin lesions; of these, 149 had lesions caused by exposure to arsenic. Of the 420 biological samples collected and analysed, 92.6% (389) contained arsenic at concentrations that were above normal. Thus many villagers might be subclinically affected. Although five arsenic-filtering devices had been installed in Rajapur, it appears that villagers are still exposed to raised concentrations of arsenic in their drinking-water. Detailed village-level studies of arsenic-affected areas in West Bengal are required in order to understand the magnitude of contamination and its effects on people. Villagers are ill-informed about the dangers of drinking arsenic-contaminated water. The contamination could be brought under control by increasing community awareness of the dangers and implementing proper watershed management techniques that involve local people.

Pattern of excretion of arsenic compounds [arsenite, arsenate, MMA(V), DMA(V)] in urine of children compared to adults from an arsenic exposed area in Bangladesh.

Urinary arsenic is generally considered as the most reliable indicator of recent exposure to inorganic arsenic and is used as the main bio-marker of exposure. However, due to the different toxicity of arsenic compounds, speciation of arsenic in urine is generally considered to be more convenient for health risk assessment than measuring total arsenic concentration. Additionally, it can give valuable information about the metabolism of arsenic species within the body. In our study, for exposed group--42 urine samples were collected from Datterhat (South) village of Madaripur district, Bangladesh and an average arsenic concentration in their drinking water was 376 microg/L (range 118 to 620 microg/L). For control group, 27 urine samples were collected from a non-affected district, Badhadamil village of Medinipur district, West Bengal, India, where arsenic concentration in their drinking water is below 3 microg/L. The arsenic species in the urine were separated and quantified by using HPLC-ICP-MS. The sum of inorganic arsenic and its metabolites was also determined by FI-HG-AAS. Results indicate that average total urinary arsenic metabolites in children's urine is higher than adults and total arsenic excretion per kg body weight is also higher for children than adults. For arsenic species between adults and children, it has been observed that inorganic arsenic (In-As) in average is 2.36% and MMA is 6.55% lower for children than adults while DMA is 8.91% (average) higher in children than adults. The efficiency of the methylation process is also assessed by the ratio between urinary concentration of putative product and putative substrate of the arsenic metabolic pathway. Higher values mean higher methylation capacity. Results show the values of the MMA/In-As ratio for adults and children are 0.93 and 0.74 respectively. These results indicate that first reaction of the metabolic pathway is more active in adults than children. But a significant increase in the values of the DMA/MMA ratio in children than adults of exposed group (8.15 vs. 4.11 respectively) indicates 2nd methylation step is more active in children than adults. It has also been shown that the distribution of the values of DMA/MMA ratio to exposed group decrease with increasing age (2nd methylation process). Thus from these results we may infer that children retain less arsenic in their body than adults. This may also explain why children do not show skin lesions compared to adults when both are drinking same contaminated water.

Neuropathy in arsenic toxicity from groundwater arsenic contamination in West Bengal, India.

Large number of people from 9 out of 18 districts of West Bengal, India are endemically exposed to arsenic contaminated groundwater due to drinking of tubewell water containing arsenic level above World Health Organization's maximum permissible limit of 50 microg/L. From our ongoing studies on neurological involvement in patients of arsenicosis from different districts of West Bengal, we report our findings in a total of 451 patients of three districts (Murshidabad, Nadia, and Burdwan), comprising 267 males and 184 females with age ranging from 11 to 79 years. They all had arsenical skin lesions, positive biomarkers and identified source of arsenic contaminated water drinking. Peripheral neuropathy was the predominant neurological complication in these patients affecting 154 (37.3%) of 413 patients of Group 1 and 33 (86.8%) of 38 patients of Group 2. Other possible causes and alternative explanations of neuropathy were excluded. The temporal profile in most of the cases (154 of Group 1) were of chronic affection while the 33 patients of Group 2 developed both neuropathy and dermopathy subacutely. Subacutely affected Group 2 patients had much higher incidence of neuropathy. Paresthesias and pains in the distal parts of extremities were much higher in incidence in Group 2 (73.7% and 23.7% respectively) than in Group 1 (18.4% and 11.1%). Distal limb weakness or atrophy was evident in 7.3% in Group 1 and 10.5% in Group 2. Overall, sensory features were more common than motor features in patients of neuropathy and sensory neuropathy was diagnosed in 30% and 76.3% and sensorimotor in 7.3% and 10.5% respectively in Group 1 and Group 2 subjects. Nerve conduction and electromyographic studies performed in 88 cases revealed dysfunction of sensory nerve in 45% and 27% and of motor nerve in 20% and 16.7% of patients with moderate degree and mild degree of clinical neuropathies respectively. Evoked potential studies performed in 20 patients were largely normal except for two instances each of abnormal visual evoked potential and brainstem auditory evoked potential findings. Prognosis was favorable in mild and early diagnosed cases of neuropathy whereas most of the other more severe and late diagnosed cases showed slow and partial recovery or even deterioration. Outcome in neuropathic patients of arsenicosis and long term toxic neurologic effects yet unexplored and unknown remain as matters of future concern requiring close monitoring.

Arsenic calamity in the Indian subcontinent What lessons have been learned?

Groundwater arsenic (As) contamination in West Bengal (WB, India) was first reported in December 1983, when 63 people from three villages of two districts were identified by health officials as suffering from As toxicity. As of October 2001, the authors from the School of Environmental Studies (SOES) have analyzed >105 000 water samples, >25 000 urine/hair/nail/skin-scale samples, screened approximately 86 000 people in WB. The results show that more than 6 million people in 2700 villages from nine affected districts (total population approximately 42 million) of 18 total districts are drinking water containing >/=50 mug l(-1) As and >300 000 people may have visible arsenical skin lesions. The As content of the physiological samples indicates that many more may be sub-clinically affected. Children in As-affected villages may be in special danger. In 1995, we had found three villages in two districts of Bangladesh where groundwater contained >/=50 mug l(-1) As. The present situation is that in 2000 villages in 50 out of total 64 districts of Bangladesh, groundwater contains As above 50 mug l(-1) and more than 25 million people are drinking water above >/=50 mug l(-1) As. After years of research in WB and Bangladesh, additional affected villages are being identified on virtually every new survey. The present research may still reflect only the tip of iceberg in identifying the extent of As contamination. Although the WB As problem became public almost 20 years ago, there are still few concrete plans, much less achievements, to solve the problem. Villagers are probably in worse condition than 20 years ago. Even now, many who are drinking As-contaminated water are not even aware of that fact and its consequences. 20 years ago when the WB government was first informed, it was a casual matter, without the realization of the magnitude this problem was to assume. At least up to 1994, one committee after another was formed but no solution was forthcoming. None of the expert reports has suggested solutions that involve awareness campaigns, education of the villagers and participation of the people. Initially, international aid agencies working in the subcontinent simply did not consider that As could be present in groundwater. Even now, while As in drinking water is being highlighted, there have been almost no studies on how additional As is introduced through the food chain, as large amounts of As are present in the agricultural irrigation water. Past mistakes, notably the ceaseless exploitation of groundwater for irrigation, continue unabated today; at this time, more groundwater is being withdrawn than ever before. No efforts have been made to adopt effective watershed management to harness the extensive surface water and rainwater resources of this region. Proper watershed management and participation by villagers are needed for the proper utilization of water resources and to combat the As calamity. As in groundwater may just be nature's initial warning about more dangerous toxins yet to come. What lessons have we really learned?

Arsenic groundwater contamination and sufferings of people in North 24-Parganas, one of the nine arsenic affected districts of West Bengal, India.

To understand the magnitude of the arsenic calamity in West Bengal, a detailed study spanning 7 years was made in North 24-Parganas, one of the nine arsenic affected districts. Area and population of North 24-Parganas district are 4093.82 sq. km and 7.3 million, respectively. Fourty eight thousand and thirty water samples were analyzed from hand tubewells of North 24-Parganas in use for drinking, cooking and 29.2% of the tubewells were found to have arsenic above 50 microg/L, the maximum permissible limit of World Health Organization (WHO) and 52.8% have arsenic above 10 microg/L, WHO recommended value of arsenic in drinking water. Out of the 22 blocks of North 24-Parganas, in 20 blocks arsenic has been found above the maximum permissible limit and so far in 16 blocks people have been identified as suffering from arsenical skin lesions. From the generated data, it is estimated that about 2.0 million and 1.0 million people are drinking arsenic contaminated water above 10 microg/L and 50 microg/L level, respectively in North 24-Parganas alone. So far, in our preliminary study 33,000 people have been examined at random from arsenic affected villages in North 24-Parganas and 2274 people have been registered with arsenical skin lesions. Extrapolation of the available data indicates about 0.1 million people may be suffering from arsenical skin lesions from North 24-Parganas alone. A sum of 21,000 hair, nail, and urine samples analyses from arsenic affected villages show 56%, 80%, and 87% people have arsenic in biological specimen more than normal/toxic (hair) level, respectively. Thus, many may be subclinically affected. Due to use of arsenic contaminated groundwater for agricultural irrigation, rice and vegetable are getting arsenic contaminated. Hence there is an additional arsenic burden from food chain. People from arsenic affected villages are also suffering from arsenical neuropathy. A followup study indicates that many of the victims suffering from severe arsenical skin lesions for several years are now suffering from cancer or have already died of cancer.