Chitta Ranjan Chanda

Arsenic poisoning in the Ganges delta.

We have been studying the contamination of groundwater by arsenic and the attend-ant human suffering in West Bengal, India, for a decade, and in Bangladesh for the past four years. From our analysis of thousands of samples of water and sediment, we have been able to test the course of events proposed by Nickson et al. to account for the poisoning of Bangladesh groundwater. We disagree with Nickson et al.s claim that arsenic concentrations in shallow (oxic) wells are mostly below 50 μg per litre. In our samples from Bangladesh (n=9,465), 59% of the 7,800 samples taken at known depth and containing arsenic at over arsenic 50 μg per litre were collected from depths of less than 30 m, and 67% of the 167 samples with arsenic concentrations above 1,000 μg per litre were collected from wells between 11 and 15.8 m deep.

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 natures initial warning about more dangerous toxins yet to come. What lessons have we really learned?

Arsenic in groundwater in six districts of West Bengal, India.

Arsenic in groundwater above the WHO maximum permissible limit of 0.05 mg l−1 has been found in six districts of West Bengal covering an area of 34 000 km2 with a population of 30 million. At present, 37 administrative blocks by the side of the River Ganga and adjoining areas are affected. Areas affected by arsenic contamination in groundwater are all located in the upper delta plain, and are mostly in the abandoned meander belt. More than 800 000 people from 312 villages/wards are drinking arsenic contaminated water and amongst them at least 175 000 people show arsenical skin lesions. Thousands of tube-well water in these six districts have been analysed for arsenic species. Hair, nails, scales, urine, liver tissue analyses show elevated concentrations of arsenic in people drinking arsenic-contaminated water for a longer period. The source of the arsenic is geological. Bore-hole sediment analyses show high arsenic concentrations in only few soil layers which is found to be associated with iron-pyrites. Various social problems arise due to arsenical skin lesions in these districts. Malnutrition, poor socio-economic conditions, illiteracy, food habits and intake of arsenic-contaminated water for many years have aggravated the arsenic toxicity. In all these districts, major water demands are met from groundwater and the geochemical reaction, caused by high withdrawal of water may be the cause of arsenic leaching from the source. If alternative water resources are not utilised, a good percentage of the 30 million people of these six districts may suffer from arsenic toxicity in the near future.

Chronic Arsenic Toxicity in Bangladesh and West Bengal, India—A Review and Commentary

Fifty districts of Bangladesh and 9 districts in West Bengal, India have arsenic levels in groundwater above the World Health Organizations maximum permissible limit of 50 μg/L. The area and population of 50 districts of Bangladesh and 9 districts in West Bengal are 118,849 km2 and 104.9 million and 38,865 km2 and 42.7 million, respectively. Our current data show arsenic levels above 50 μg/L in 2000 villages, 178 police stations of 50 affected districts in Bangladesh and 2600 villages, 74 police stations/blocks of 9 affected districts in West Bengal. We have so far analyzed 34,000 and 101,934 hand tube-well water samples from Bangladesh and West Bengal respectively by FI-HG-AAS of which 56% and 52%, respectively, contained arsenic above 10 μg/L and 37% and 25% arsenic above 50 μg/L. In our preliminary study 18,000 persons in Bangladesh and 86,000 persons in West Bengal were clinically examined in arsenic-affected districts. Of them, 3695 (20.6% including 6.11% children) in Bangladesh and 8500 (9.8% including 1.7% children) in West Bengal had arsenical dermatological features. Symptoms of chronic arsenic toxicity developed insidiously after 6 months to 2 years or more of exposure. The time of onset depends on the concentration of arsenic in the drinking water, volume of intake, and the health and nutritional status of individuals. Major dermatological signs are diffuse or spotted melanosis, leucomelanosis, and keratosis. Chronic arsenicosis is a multisystem disorder. Apart from generalized weakness, appetite and weight loss, and anemia, our patients had symptoms relating to involvement of the lungs, gastrointestinal system, liver, spleen, genitourinary system, hemopoietic system, eyes, nervous system, and cardiovascular system. We found evidence of arsenic neuropathy in 37.3% (154 of 413 cases) in one group and 86.8% (33 of 38 cases) in another. Most of these cases had mild and predominantly sensory neuropathy. Central nervous system involvement was evident with and without neuropathy. Electrodiagnostic studies proved helpful for the diagnosis of neurological involvement. Advanced neglected cases with many years of exposure presented with cancer of skin and of the lung, liver, kidney, and bladder. The diagnosis of subclinical arsenicosis was made in 83%, 93%, and 95% of hair, nail and urine samples, respectively, in Bangladesh; and 57%, 83%, and 89% of hair, nail, and urine samples, respectively in West Bengal. Approximately 90% of children below 11 years of age living in the affected areas show hair and nail arsenic above the normal level. Children appear to have a higher body burden than adults despite fewer dermatological manifestations. Limited trials of 4 arsenic chelators in the treatment of chronic arsenic toxicity in West Bengal over the last 2 decades do not provide any clinical, biochemical, or histopathological benefit except for the accompanying preliminary report of clinical benefit with dimercaptopropanesulfonate therapy. Extensive efforts are needed in both countries to combat the arsenic crisis including control of tube-wells, watershed management with effective use of the prodigious supplies of surface water, traditional water management, public awareness programs, and education concerning the apparent benefits of optimal nutrition.

Impact of safe water for drinking and cooking on five arsenic-affected families for 2 years in West Bengal, India

The groundwater in seven districts of West Bengal, India, covering an area of 37,000 km2 with a population of 34 million, has been contaminated with arsenic. In 830 villages/wards more than 1.5 million people, out of the total population, drink the arsenic-contaminated water. Safe water from a source having < 0.002 mg 1(-1) arsenic has been supplied for 2 years to five affected families comprising 17 members (eight of them with arsenical skin-lesions) of different age groups for impact assessment study in terms of loss of arsenic through urine, hair and nail. The study indicates random observable fluctuations of arsenic concentration in urine among members on different scheduled sampling days with a declining trend, particularly during the first 6 months. Furthermore, the investigation showed that despite having safe water for drinking and cooking, the study group could not avoid an intake of arsenic, time and again, through edible herbs grown in contaminated water, food materials contaminated through washing, and the occasional drinking of contaminated water. After minimizing the level of contamination, a noteworthy declining trend after 8 months was observed in urine, hair and nails in all the cases, but not to that level observed in a normal population, due to prevailing elevated background level of arsenic in the area. The eight members, who had already developed skin lesions, are far from recovering completely, indicating a long-lasting damage. Statistical interpretation of the data are considered.

Neuropathy in Arsenic Toxicity from Groundwater Arsenic Contamination in West Bengal, India

Abstract 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 Organizations maximum permissible limit of 50 µg/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 Groundwater Contamination and Sufferings of People in North 24-Parganas, One of the Nine Arsenic Affected Districts of West Bengal, India

Abstract 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 µg/L, the maximum permissible limit of World Health Organization (WHO) and 52.8% have arsenic above 10 µg/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 µg/L and 50 µg/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.

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

Abstract 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 µg/L (range 118 to 620 µg/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 µg/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 childrens 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.

Arsenic in groundwater in six districts of West Bengal, India: the biggest arsenic calamity in the world: the status report up to August, 1995

In six districts of West Bengal: Malda, Murshidabad, Bardhaman, Nadia, 24-Parganas (North) and 24-Parganas (South), arsenic has been found in groundwater above the maximum permissible limit recommended by WHO. The current provisional arsenic level in drinking-water from WHO is 0.01 μl−1 (WHO, 1993). This water is used by villagers for drinking, cooking and other household purposes. Saha (Saha, 1984, 1985, 1995; Saha and Poddar, 1986) reported 1214 cases of chronic arsenical dermatosis from drinking arsenic contaminated tube-well water in 47 villages in these six districts. During January 1988-August 1995 a further survey was conducted by the School of Environmental Studies in these districts and the present estimation indicates that 44 blocks in these six districts are affected that includes 466 villages and many municipal areas. About 1.0 million people were drinking arsenic-contaminated water and about 200000 people have arsenical skin lesions. The total population and area of these six districts are 30 million and 34000 km2 respectively. Every month we are finding additional arsenic-affected villages. These 30 million people are at risk.

Groundwater Arsenic Contamination and Sufferings of People in West Bengal, India and Bangladesh

Groundwater is becoming the major source of drinking water around the world, especially in developing countries, to avoid microbial and chemical contamination from surface water. Another reason of wide use of groundwater is that because of its easy access and economic viability. Not only is groundwater being used for drinking, but for farmers in many developing countries like India, Bangladesh groundwater is their main source of irrigation. These countries have achieved a green revolution with the help of underground water. Earlier, India and Bangladesh could get only one crop a year, and that too was rain dependent. But now usually 3/4 crops in a year are common and the source of water for irrigation lies underground. Irrigation in West Bengal and Bangladesh using groundwater was first started around the sixties. In both these countries, there is no groundwater withdrawal regulation. As a result, groundwater exploitation goes on unchecked. In Bangladesh and West Bengal more than 95% of the Rural Water Supply Schemes (RWSS) depend on underground water. Dhaka (population abut 11 million) is the only city in the world where more than 97% of the domestic water requirement comes from underground water sources.