Tarit Roy Chowdhury

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 in ground water in six districts of West Bengal, India: the biggest arsenic calamity in the world. Part I. Arsenic species in drinking water and urine of the affected people

Arsenic in ground water has been found above the maximum permissible limit in six districts of West Bengal covering an area of 34 000 km2 with a population of 30 million. At present 37 blocks of these six districts by the side of the River Ganga are affected and about 800 000 people from 312 villages/wards are drinking arsenic contaminated water and amongst them at least 175 000 people are showing arsenical skin lesions. The source of arsenic is geological. We have analysed thousands of tube-well water samples from these six districts for four arsenic species namely, arsenite, arsenate, monomethylarsonic acid (MMAA) and dimethylarsinic acid (DMAA). We could detect no MMAA or DMAA in any of these samples. In urine, DMAA and MMAA are the predominant species along with arsenite and arsenate. The techniques we used for the determination and speciation of arsenic are: (i) separation of arsenite and arsenate from water by sodium diethyldithiocarbamate in chloroform followed by FI-HGAAS; (ii) spectrophotometry using Ag–DDTC in chloroform with hexamethylenetetramine as absorbing solution; (iii) ion-exchange separation of arsenite and arsenate from water followed by FI-HGAAS; and (iv) for analysis of inorganic arsenic and its metabolites in urine, FI-HGAAS was used after separation of the species by a combined cation–anion-exchange column. Total arsenic in urine was determined by FI-HGAAS after acid decomposition. The most toxic species, arsenite, is present in ground water at about 50% of the total arsenic level, and more than 90% of the total arsenic in urine is inorganic arsenic and its metabolites.

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.

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.

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.

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.

Arsenic in the breast milk of lactating women in arsenic-affected areas of West Bengal, India and its effect on infants

Two hundred and twenty-six breast milk samples were collected from lactating women from 3 blocks of North-24 Paragans, one of the arsenic-affected districts of West Bengal, India. Out of 226 samples, only in 39 samples arsenic was detected. Urine, hair, and nail samples were also analyzed to know the arsenic body burden of the lactating women. Arsenic in drinking water was also analyzed. Principle component analysis (PCA) revealed that hair and nail arsenic was highly correlated with water arsenic concentrations, whereas arsenic in urine and breast milk did not cluster with water arsenic. Our present study indicated that among the lactating women who had high arsenic body burden and arsenical skin lesions, they had elevated level of arsenic in their breast milk. Arsenic in hair, nails, and urine samples of infants were analyzed, and the results showed significantly high-body burden of infants in those areas. PCA showed the age-dependent relationship between the hair and nail arsenic concentrations of the mothers and their babies.

Groundwater Arsenic Contamination and Suffering of People in Bangladesh

Publisher Summary The total area and population of Bangladesh are 148,393 km2 and 120 million respectively. To date, 9089 water samples collected from 60 districts have been analyzed and arsenic (As) concentrations in 41 districts have been found to be above 50 μg/l. The area and population of these 41 districts are 89,186 km2 and 76.9 million respectively. This does not mean the total population in these 41 districts are drinking contaminated water and suffering from aresenicosis, but no doubt they are at risk. About 3000 each of hair and nail samples from people living in As-affected villages (including patients) have so far been analyzed and 97% of the hair samples contain aresenic above the toxic level and 95% of the nail samples contain above the normal level. Out of the 41 districts where As has been found above 50 μg/l authors have, so far, 22 districts have been surveyed for arsenicosis patients, and in 21 districts people suffering from As-induced skin lesions have been identified.

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.

Increased microRNA 21 expression contributes to arsenic induced skin lesions, skin cancers and respiratory distress in chronically exposed individuals

More than 26 million people in West Bengal, India, are exposed to arsenic through drinking water, leading to several deleterious endpoints including precancerous and cancerous skin lesions and other non-dermatological health effects. Here, our aim was to identify whether miR21 is associated with such dermatological and non-dermatological health outcomes in chronically exposed humans. A total of 123 subjects from West Bengal were recruited for this study (45 exposed individuals with skin lesions, 38 exposed individuals without skin lesions and 40 unexposed individuals). The miR21 expression patterns in the lymphocytes were studied by quantitative realtime PCR and the effects on downstream targets were validated by Western blotting. Associations between the miR21 expression patterns and non-dermatological health effects were determined from epidemiological survey data. In vitro studies were done with low dose (0.05ppm) of chronic arsenic exposure to HaCaT cells for 15 passages. Interestingly, within the exposed group, the skin lesion individuals showed almost 4.5 fold up-regulation of miR21 compared to the no skin lesion group. The expression of the downstream targets of miR21 (PTEN and PDCD4) varied inversely, while the expression of pAKT and PI3K varied proportionately with its expression levels. Results of in vitro studies showed similar trends. Again miR21 was 2.03 fold up-regulated in the exposed individuals with respiratory diseases compared to the individuals without the same. This study for the first time shows that miR21 plays an important role in contributing to arsenic induced dermatological and non-dermatological health outcomes in an exposed population.