Murshidabad-One of the Nine Groundwater Arsenic-Affected Districts of West Bengal, India. Part I: Magnitude of Contamination and Population at Risk
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Clinical Toxicology, 43:823–834, 2005
Copyright D Taylor & Francis Inc.
ISSN: 0731-3810 print / 1097-9875 online
DOI: 10.1080/15563650500357461
ARTICLE
Murshidabad—One of the Nine Groundwater
Arsenic-Affected Districts of West Bengal, India.
Part I: Magnitude of Contamination and Population at Risk
Mohammad Mahmudur Rahman, Mrinal Kumar Sengupta, Sad Ahamed, Dilip Lodh,
Bhaskar Das, M. Amir Hossain, Bishwajit Nayak, Amitava Mukherjee,
and Dipankar Chakraborti
School of Environmental Studies, Jadavpur University, Kolkata, India
Subhash Chandra Mukherjee
Department of Neurology, Medical College and Hospital, Kolkata, India
Shymapada Pati
Department of Obstetrics and Gynaecology, Institute of Post Graduate Medical Education and
Research, S.S.K.M. Hospital, Kolkata, India
Kshitish Chandra Saha
Former Professor, Department of Dermatology, School of Tropical Medicine, Kolkata, India
Shyamal Kanti Palit, Imrul Kaies, Ajoy Kishore Barua, and
Khondaker Abdul Asad
Dhaka Community Hospital, Dhaka, Bangladesh
3800 biologic (nail, urine, and hair) samples from arsenic-affected
Introduction. To understand the severity of the arsenic crisis villages revealed that 95% of the nail and 94% of the urine
in West Bengal, India, a detailed, 3-year study was undertaken in samples contained arsenic above the normal levels and 75% of
Murshidabad, one of the nine arsenic-affected districts in West the hair samples were found to have arsenic above the toxic level.
Bengal. The district covers an area of 5324 km2 with a population Thus, many villagers in the affected areas of Murshidabad might
of 5.3 million. Methods. Hand tubewell water samples and be subclinically affected. Discussion and Conclusion. Compar-
biologic samples were collected from Murshidabad and analyzed ing our extrapolated data with international dose response
for arsenic by FI-HG-AAS method. Inter laboratory analysis and results, we estimated how many people may suffer from arsenical
analyses of standards were undertaken for quality assurance. skin lesions and cancer. Finally, if the exposed population is
Results. During our survey we analyzed 29,612 hand tubewell provided safe water, better nutrition, and proper awareness
water samples for arsenic from both contaminated and non- about the arsenic problem, lives can be saved and countless
contaminated areas, and 26% of the tubewells were found to have suffering of the affected population can be avoided.
arsenic above 50 mg/L while 53.8% had arsenic above 10 mg/L. Of
the 26 blocks in Murshidabad, 24 were found to have arsenic Keywords Murshidabad district; Arsenic groundwater contamination;
above 50 mg/L. Based on our generated data we estimated that Exposure to arsenic contamination; Arsenic in biologic
approximately 0.2 million hand tubewells are installed in all 26 samples
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
INTRODUCTION
50 mg/L levels respectively in this district. The analysis of total The groundwater in five Indian states (West Bengal, Bihar,
Uttar Pradesh, Jharkhand, and Assam) and Bangladesh that lie
in the Ganga-Meghna-Brahmaputra (GMB) plain are more or
Address correspondence to Dipankar Chakraborti, School of less arsenic contaminated (1). Of the five states of India, West
Environmental Studies, Jadavpur University, Kolkata 700 032, India. Bengal is seriously affected (1 – 6). The first case of arsenic
E-mail: dcsoesju@vsnl.com poisoning in West Bengal was reported in 1984 (6,7). Since
823
Order reprints of this article at www.copyright.rightslink.com824 M. M. RAHMAN ET AL. FIG. 1. Distribution of arsenic concentration in different blocks of the Murshidabad district indicating the location of the Murshidabad district in West Bengal, India.
ARSENIC CONTAMINATION IN MURSHIDABAD: PART I 825
1988 our team has been surveying arsenic-affected villages in cancer in the Murshidabad district by comparison with
West Bengal, but we feel our present research is merely the tip international data.
of the iceberg of West Bengal’s arsenic problem. The analysis
of the data from our 17 years of field survey involving more
than 129,000 hand tubewells water samples revealed that 3200 METHODS
villages covering 85 blocks in nine out of the total 18 districts Description of the Study Area, Murshidabad District
in West Bengal are arsenic affected (1). Out of the nine
The administrative structure of West Bengal consists of 18
arsenic-affected districts of West Bengal, four (North 24-
districts and Murshidabad is one of them. Each district of West
Pargana, Nadia, Murshidabad, and Malda) are severely
Bengal has several blocks. In Murshidabad, there are 26
affected, one (South 24-Pargana) is moderately affected, and
blocks. Each block has several gram panchayets (GPs), which
the remaining four (Barddhaman, Howrah, Hoogly, and
are clusters of villages. There are 262 GPs including municipal
Kolkata) are less affected. However, our study shows that
areas (known as wards) in the Murshidabad district. There are
within a span of 3 years and more, arsenic safe tubewells
2414 villages and wards in this district. Extending over an area
(arsenic < 10 mg/L) are becoming unsafe (arsenic >50 mg/L) in
of 5324 km2, the district has 5,396,351 inhabitants living in 26
some villages (8,9). The analytical results showed 49.6% of
blocks (according to the Census 2001). The river Ganges/
the hand tubewells had arsenic above 10 mg/L [the World
Padma forms its northern and eastern boundaries and separates
Health Organization (WHO) provisional guideline value for
it from Bangladesh. The river Bhagirathi flows across the
arsenic in drinking water] and 24.7% had above 50 mg/L (the
district and divides it in two parts. Figure 1 shows the
permissible limit of arsenic in drinking water in most
Murshidabad district and its position in West Bengal.
developing countries) in West Bengal (1). We analyzed
28,000 biologic samples (urine, hair, nail, and skin-scale) for
arsenic from the affected villages of West Bengal, and on Instrumentation
average, 78% of the samples showed arsenic above the normal The flow injection hydride generation atomic absorption
levels (1). In our preliminary survey, we screened 92,000 spectrometry (FI-HG-AAS) method was used for arsenic
people, and 8900 (9.6%) of these from 325 villages were analysis. Details of the instrumentation and the flow injection
registered with arsenical skin lesions (1). The area of West system have been described in our earlier publications
Bengal covers 89,193 km2 and has a population of about 80 (10 –13).
million. About 50 million people are living in nine arsenic-
affected districts of West Bengal covering an area of 38,865 Samples Collection and Arsenic Analysis
km2. This does not mean that all the people living in arsenic- We spent around 5800 hours (four persons 8 hours 182
affected areas are drinking arsenic-contaminated water and days) for collecting water samples and from December 2000
will suffer from arsenic-related diseases, but undoubtedly they to July 2003, more than 5000 hours (100 days seven
are running a risk. persons 8 hours) to collect biologic samples and identifica-
We decided to concentrate our study on one of the nine tion of arsenic patients from the villages of Murshidabad. Spot
affected districts of West Bengal. We carried out a detailed urine samples were collected on a single occasion. The modes
survey of the Murshidabad district as we had the maximum of water and biologic samples collection, the digestion
preliminary information from the district, and some of our procedures for hair and nail, and the analytical procedures
field workers are from the same district. Although our group were as reported earlier (10 – 12).
had worked in this district sporadically since 1991, from June Hand tubewell water, hair, nail, and urine samples were
2000 to July 2003, we concentrated our entire effort, very analyzed for arsenic by the FI-HG-AAS method. For urine
systematically on this single district to understand in depth the samples, only inorganic arsenic and its metabolites together
arsenic contamination situation and its related effect on [arsenite, As (III); aresenate, As (V); monomethyl arsonic
people’s health. acid, MMA (V); and dimethyl arsinic acid, DMA (V)] were
On the basis of our field survey in the Murshidabad district, measured with no chemical treatment. Under the experimental
this article presents 1) arsenic contamination status of the conditions of FI-HG-AAS, arsenobetaine and arsenocholine
groundwater in Murshidabad and the expected number of hand do not produce a signal (10). For hair and nail samples we
tubewells there, and hence in nine arsenic-affected districts of determined total arsenic after digestion.
West Bengal, 2) the variation in arsenic concentration with
depth of the tubewells, 3) arsenic in the biologic samples taken Quality Assurance and Quality Control Program
from the villagers in the affected blocks of Murshidabad, 4) an For quality control, inter-laboratory tests were performed
estimation of the population drinking contaminated water at for water and hair samples as reported in our earlier
various concentration levels of arsenic in Murshidabad (only publications (12,14). We had also analyzed EPA water
on the basis of our field survey) and 5) the estimation of the standards and biologic standard reference materials including
population that may suffer from arsenical skin lesions and hair and urine; details have been reported elsewhere (12 – 15).826
TABLE 1
Distribution of hand tubewell water samples of different arsenic concentration ranges (mg/L) in Murshidabad district
Total water Distribution of total samples in different arsenic concentration ranges (mg/L)
Name of samples
Part blocks analyzed 1000
Behrampur 1820 928 608 176 97 8 3 – –
Beldanga-I 1395 531 381 190 180 65 31 15 2
Beldanga-II 1034 638 266 74 55 1 – – –
Bhagowangola-I 1775 669 561 162 333 36 5 5 4
Bhagowangola-II 818 220 246 127 138 60 13 10 4
Domkal 3366 979 1207 417 559 140 47 15 2
Hariharpara 1512 535 472 179 202 96 21 6 1
Jalangi 1916 400 541 282 363 181 69 42 38
Jiaganj 1234 680 374 122 58 – – – –
Eastern Lalgola 1026 259 412 163 165 14 7 5 1
Nawda 1205 426 525 131 90 20 8 4 1
Raghunathganj-I 515 417 37 35 18 7 1 – –
Raghunathganj-II 1225 291 379 347 179 23 3 3 –
Raninagar-I 772 239 259 117 149 6 1 – 1
Raninagar-II 2211 716 639 179 422 193 45 10 7
Bharatpur-I 616 572 42 2 – – – – –
Bharatpur-II 625 625 – – – – – – –
Burwan 699 690 7 2 – – – – –
Farrakka 489 109 293 81 6 – – – –
Western Kandi 932 878 46 7 1 – – – –
Khargrma 715 686 26 3 – – – – –
Nabagram 705 688 17 – – – – – –
Sagardighi 706 658 31 16 1 – – – –
Shamsherganj 876 171 496 109 100 – – – –
Suti-I 443 137 87 101 98 19 – 1 –
Suti-II 982 168 452 143 156 37 13 6 7
Murshidabad (No. of 29612 13310 8404 3165 3370 906 267 122 68
Blocks = 26) (44.9%) (28.4%) (10.7%) (11.4%) (3.1%) (0.9%) (0.4%) (0.2%)ARSENIC CONTAMINATION IN MURSHIDABAD: PART I 827
RESULTS results showed that 53.8% of the hand tubewells had arsenic
above 10 mg/L and 26% had above 50 mg/L. It can be noted
Arsenic Contamination Status of the Groundwater
that only the groundwater of Bharatpur-II block was within the
in Murshidabad
WHO provisional guideline value of arsenic at 10 mg/L and
A total of 29,612 hand tubewell water samples were therefore safe to drink. Although the blocks in the western
collected from 1833 out of the total 2414 villages (covering bank of river Bagirathi were less arsenic contaminated, some
entire area of the village) in 26 blocks in Murshidabad. The of the blocks such as Suti-I, Suti-II, and Raghunathganj-I were
arsenic concentration in the water sample was observed to be identified with a high degree of contamination.
above 10 mg/L in 1380 villages and wards, and in 994 villages
and wards above 50 mg/L. Table 1 shows the distribution of
arsenic in 29,612 hand tubewell water samples from all 26 Expected Number of Hand Tubewells in Murshidabad,
blocks of Murshidabad district and Fig. 1 shows the Hence in Nine Arsenic-Affected Districts of
groundwater arsenic contamination status in all 26 blocks of West Bengal
Murshidabad. From Table 1 and Fig. 1, it appears that the There are no officially available statistics on the number of
blocks situated in the western side of the Bhagirathi river were hand tubewells in the 26 blocks of the Murshidabad district.
less affected (n = 8303, 30.1% above 10 mg/L, 11.7% above More than 90% of the existing tubewells in Murshidabad are
50 mg/L) than the blocks located on the east bank (n =21,309, privately installed. Usually water is available from these hand
64.7% above 10 mg/L, 32.5% above 50 mg/L). The combined tubewells all year round, even at shallow depths of about 8 m.
TABLE 2
An estimation of the number of hand tubewells in Murshidabad district
Average number
No. of of users No. of
Total tubewells Tubewells whose per hand expected hand
Name of blocks population analyzed users are known tubewells tubewells
Behrampur 378830 1820 1764 23 16470
Beldanga-I 259139 1395 1344 22 11779
Beldanga-II 210195 1034 988 26 8084
Bhagowangola-I 163438 1775 655 29 5635
Bhagowangola-II 129907 818 786 26 4996
Bharatpur-I 150839 616 593 64 2356
Bharatpur-II 150115 625 599 32 4691
Burwan 224312 699 657 71 3159
Domkal 311683 3366 3307 20 15584
Farrakka 219775 489 485 45 4883
Hariharpara 221709 1512 781 18 12317
Jalangi 215538 1916 1877 35 6158
Jiaganj 199621 1234 1192 21 9505
Kandi 192952 932 88 75 2572
Khargrma 234715 715 682 64 3667
Lalgola 267563 1026 1000 22 12161
Nabagram 196565 705 698 51 3854
Nawda 196021 1205 1151 17 11530
Raghunathganj-I 154349 515 508 42 3674
Raghunathganj-II 192505 1225 1210 23 8369
Raninagar-I 154559 772 444 12 12879
Raninagar-II 155612 2211 689 14 11115
Sagardighi 252360 706 684 53 4761
Shamsherganj 211561 876 870 31 6824
Suti-I 139419 443 438 25 5576
Suti-II 213069 982 930 27 7891
Murshidabad (No. of Blocks = 26) 5396351 29612 200490828 M. M. RAHMAN ET AL. The installation of a hand tubewell consisting of a single pipe 31% of the total hand tubewells in the Jalangi block. To verify and filter (at a depth of about 8 m) is quite affordable and costs our method of estimation we surveyed the Sagarpara GP of the about US $50 (16). In the arsenic-affected areas of West Jalangi block in detail. The population of Sagarpara was Bengal and Bangladesh many families use water from more 24,419. Of the 679 hand tubewells in this GP, we analyzed 565 than one hand tubewell for their domestic needs. Also, the (83%) for arsenic. The rest of the tubewells were defunct number of hand tubewells in Murshidabad is not equally during our survey. In fact, one may expect some percentage of distributed among its 26 blocks. Still, to get an approximate the total tubewells in defunct condition in a village. With total number of hand tubewells in Murshidabad, we made a 24,419 people to 679 hand tubewells, we determined that, on simple calculation using our field survey data on the number of an average, 36 people were using one hand tubewell in the users for each hand tubewell for each block of Murshidabad. Sagarpara GP. This result is along the line of our extrapolated Table 2 shows the average number of users of each tubewell estimate for the Jalangi block. From another one of our studies from each block and the expected number of hand tubewells on the number of users per hand tubewell in arsenic-affected for the Murshidabad district. From Table 2, we observe that villages of Bangladesh, we found that, on an average, 24 approximately 0.2 million hand tubewells are installed in the people were using a single hand tubewell (1,17). Furthermore, 26 blocks of the Murshidabad district, though their distribution our detailed study of the arsenic-affected district, North 24- may not be equal throughout the blocks. However, we Parganas, and other blocks of West Bengal showed that, on an analyzed 29,612 hand tubewells, which was only 14.8% of average, 20 people were using a single hand tubewell in these the total estimated number of hand tubewells in Murshidabad. regions (16). The calculation procedure is explained below. Using similar calculations and based on the analysis of For example, in the Jalangi block we analyzed 1916 hand more than 129,000 hand tubewells from nine arsenic-affected tubewells, of which we could collect the number of users for districts of West Bengal, there would be approximately 1.8 1877 tubewells. Our field data showed that on an average 35 million hand tubewells in the nine arsenic-affected districts of people were using one hand tubewell from the Jalangi block. West Bengal. Interestingly, one of our recent studies showed The population of the Jalangi block was 215,538 (according to an increase of 24% hand tubewells in the block of Deganga 2001 Census), so we extrapolated that there were about 6158 in the North 24-Parganas district of West Bengal during last hand tubewells in the Jalangi block. We thus analyzed around 6 years (8). FIG. 2. Comparative bar diagram of arsenic concentration (mg/L) in safe and unsafe hand tubewells of the Murshidabad district against depth (m).
ARSENIC CONTAMINATION IN MURSHIDABAD: PART I 829
Variation in the Arsenic Concentration with Depth in 4813 (19%) of them were found to have arsenical skin lesions.
the Tubewells of Murshidabad From the affected blocks of Murshidabad we collected and
We had reported earlier (2) that arsenic concentration in the analyzed 1136 hair, 1523 nail, and 1184 urine samples. About
hand tubewells of West Bengal and Bangladesh usually 50% of the samples were from people with arsenical skin
decreased with depth. From all 26 blocks of Murshidabad lesions and the rest were from those without skin lesions. The
29,612 water samples were collected from hand tubewells of analytical results of hair, nail, and urine samples are presented
varying depths. However, we could ascertain the depth in Table 3, which also has the arsenic concentrations in the
information of 25,630 hand tubewells out of the 29,612. hair, nail, and urine samples of a control population
The depth distribution against mean arsenic concentration (Medinipur, a nonarsenic-affected district) of West Bengal
for all 25,630 hand tubewells as well as 14,273 unsafe for sake of comparison. We observe that 75% of hair, 95% of
tubewells (with reference to WHO provisional guideline nail, and 94% of urine samples had arsenic above the normal
value) is shown in Fig. 2. From Fig. 2, we observe that in levels for nail and urine and at toxic levels for hair. The normal
all the tubewells, including the unsafe ones, arsenic concen- levels of arsenic in hair, nail, and urine are mentioned along
tration increased with depths up to 30.7 m. In the case of the with references in Table 3. It is noteworthy that many villagers
unsafe tubewells, the mean arsenic concentration showed an not exhibiting arsenical skin lesions had elevated level of
increasing trend up to 45.9 m. Afterward, in both cases it arsenic in hair, nail, and urine samples and thus could be
decreased with depth. For unsafe tubewells the overall trend subclinically affected. High levels of arsenic in the biologic
was decreasing, though some irregularities could be observed. samples from the villagers might be due to the fact that we
For all the wells, mean arsenic concentration decreased except collected the samples from the contaminated areas. However,
for the ranges 61.3– 91.6 m. Groundwater in the Murshidabad we do not expect such high concentrations of arsenic in the
district is mainly under unconfined conditions up to a depth of biologic samples throughout the Murshidabad district.
about 150 m below ground level (18).
Estimation of the Population Drinking
Arsenic in the Biologic Samples from Villagers in the Arsenic-Contaminated Water at Different
Affected Blocks of Murshidabad Concentration Levels
During our survey, we screened 25,274 people from 139 To get an estimate of the population size drinking arsenic-
arsenic-affected villages of 12 blocks in Murshidabad, and contaminated water above concentration levels 10, 50, 100,
TABLE 3
Concentration of arsenic in hair, nail, and urine (metabolites) collected from the arsenic-affected blocks in Murshidabad
Samples from arsenic-affected Samples from
villages of Murshidabad controlled population
Arsenic Arsenic Arsenic Name of the Arsenic Arsenic Arsenic
in haira in nailb in urinec blocks from where in haira in nailb in urinec
Parameters (mg/Kg) (mg/Kg) (mg/L) samples collected (mg/Kg) (mg/Kg) (mg/L)
No. of observations 1136 1523 1184 Beldanga-I, 75 75 75
Mean 2373 5512 221 Behrampur, 341 748 16
Median 1758 4357 120 Bhagowangola-I, 338 743 15
Minimum 222 589 10 Bhagowangola-II, 499 1066 41
Maximum 18245 35076 2870 Domkal, 217 540 10
Standard deviation 1972 4271 294 Hariharpara, 103 107 10
% of samples having 75 95 94 Jalangi, – – –
arsenic above Lalgola,
normal/toxic Nawda,
(hair) level Raninagar-I,
Raninagar-II,
Suti-II
a
Normal level of arsenic in hair ranges from 80 – 250 mg/Kg; 1000 mg/Kg is the indication of toxicity (23).
b
Normal level of arsenic in nail ranges from 430 – 1080 mg/Kg (24).
c
Normal excretion of arsenic in urine ranges from 5 – 40 mg/1.5 L (per day) (25).830
TABLE 4
Population drinking arsenic-contaminated water above 10, 50, 100, 125, 200, 250, 300, 500, and 1000 mg/L in Murshidabad
Total no. of No. of People drinking arsenic-contaminated water
Total tubewells tubewells
Name of blocks population expected analyzed > 10 mg/L > 50 mg/L > 100 mg/L > 125 mg/L > 200 mg/L > 250 mg/L > 300 mg/L > 500 mg/L > 1000 mg/L
Behrampur 378830 16470 1820 517777 59097 21593 15532 5303 3031 1894 606 –
Beldanga-I 259139 11779 1395 157815 89662 53642 44312 30319 24877 20731 8810 362
Beldanga-II 210195 8084 1034 76511 26485 10510 6726 2522 1051 210 – –
Bhagowangola-I 163438 5635 1775 100187 50175 34485 26314 10950 5720 4249 1291 360
Bhagowangola-II 129907 4996 818 93013 55860 34555 28450 21435 18187 13380 4287 637
Bharatpur-I 150839 2356 616 8749 453 – – – – – – –
Bharatpur-II 150115 4691 625 – – – – – – – – –
Burwan 224312 3159 699 2243 628 – – – – – – –
Domkal 311683 15584 3366 217866 109089 69505 55791 33350 23688 18389 5922 187
Farrakka 219775 4883 489 167249 39120 2637 879 – – – – –
Hariharpara 221709 12317 1512 140342 74051 47667 40794 30596 24831 17737 4102 133
Jalangi 215538 6158 1916 167688 109708 77162 68541 51082 42029 36641 16596 4310
Jiaganj 199621 9505 1234 87035 29145 9183 4392 1198 319 – – –
Kandi 192952 2572 932 7525 1544 193 193 – – – – –
Khargrma 234715 3667 715 7511 939 – – – – – – –
Lalgola 267563 12161 1026 195589 92577 47359 31037 11238 8830 6957 3398 260
Nabagram 196565 3854 705 2162 – – – – – – – –
Nawda 196021 11530 1205 125257 41360 18426 13525 8233 6273 5293 2117 163
Raghunathganj-I 154349 3674 515 28400 18213 7409 5711 4785 4167 2007 293 –
Raghunathganj-II 192505 8369 1225 144956 87205 31571 20406 8663 6160 4620 943 –
Raninagar-I 154559 12879 772 105255 54868 30448 21638 6182 3400 1546 402 201
Raninagar-II 155612 11115 2211 103171 60222 46995 41393 29255 23031 17740 4357 482
Sagardighi 252360 4761 706 14889 6057 252 – – – – – –
Shamsherganj 211561 6824 876 166075 50352 23695 16290 5077 1481 – – –
Suti-I 139419 5576 443 95223 68873 36110 27047 15057 8783 5716 – –
Suti-II 213069 7891 982 174290 78622 46662 38992 23225 17472 13210 5540 1513
Murshidabad (No. of 5396351 200490 29612 2564778 1204305 650059 507963 298470 223330 170320 58664 8608
Blocks = 26)ARSENIC CONTAMINATION IN MURSHIDABAD: PART I 831
TABLE 5
Probable estimation of population may suffer from arsenical skin lesions and cancer in Murshidabad
compared with international data
No. of cases expected
Study (author/year) Country/region Health effect studied for Murshidabad
Astolfi et al., 1981 (20) Cordoba, Regular intake of drinking water 0.6 million
Argentina containing above 100 mg/L of
arsenic leads to clearly recognizable
signs of arsenic toxicity and ultimately
in some cases to skin cancer
Tsuda et al., 1995 (26) Nigata, Japan Exposure for 5 years to a high dose of 0.6 million
arsenic (> 100 mg/L) can cause skin
signs of chronic arsenicism and
subsequent cancer development
USEPA, 1992 (27) – Chronic intake of 10 mg/Kg arsenic per day or 0.5 million
higher may result in dermatogical and other
sign of arsenic toxicity. 10 mg/Kg per day is
equivalent to 125 mg/L of arsenic in
tubewell water considering from our field
study, average 50 kg body weight for
adults and 4 L of water
consumption per day (5).
Chakraborty and Saha, West Bengal, The lowest arsenic concentration in drinking 0.3 million
1987 (21) India water that produced dermatosis was found
to be 200 mg/L
Oshikawa, 1998 (29) Thailand The prevalence of arsenic dermatosis in areas 0.3 million
with 200 mg/L of arsenic in drinking water
WHO, 1981 (30) – Several years of exposure of approximately 0.22 million
1000 mg of arsenic per day may cause
skin effects within just a few years. In
arsenic-affected areas of West Bengal, adults
drink an average 4 L of water per day (5).
So 1000 mg of arsenic per day is
equivalent to 4 L of 250 mg/L of
arsenic-containing water.
Morales et al., 2000 (31) Taiwan The lifetime risk of death is 1 in 100 12043
from consuming 50 mg/L of arsenic
in drinking water.
NRC, 2001 (28,32) – Cancer mortality risks to be about 1 12043
in 100 at 50 mg/L of arsenic
Smith et al., 2002, Chile Lifetime risk of dying from cancer 15655*
1992 (33,34) while drinking 1 L of water per day
with 50 mg/L of arsenic is 13 of 1000
Smith et al., 1999 (35) Chile Lifetime risk of dying from cancer while 7626*
drinking 1 L of water per day with
500 mg/L of arsenic is 13 of 100
Chakraborti et al., West Bengal, Ingestion of 300 mg/L of arsenic in 0.17 million
2002 (6) India and drinking water for couple of years
Bangladesh may cause arsenical skin lesions
*Since in arsenic-affected areas of West Bengal, adults drink an average 4 L of water per day (5), we expect a higher number of patients.832 M. M. RAHMAN ET AL.
125, 200, 250, 300, 500, and 1000 mg/L, a scientific approach even at 100 and 200 mg/L concentration of arsenic (20,21),
was taken on the basis of the data generated for the last 3 years from our 17-year-long field experience in Bangladesh and the
covering 76% of the total villages in all 26 blocks of the rest of West Bengal we observed that ingestion of 300 mg/L
Murshidabad district. Table 4 shows the total number of arsenic for a couple of years may cause skin lesions (6,16). On
tubewells analyzed, expected total number of hand tubewells this basis the theoretical estimate of population at risk from
(as from Table 2), and expected population size drinking skin lesions in Murshidabad comes to 0.17 million (Table 5).
arsenic-contaminated water at different arsenic concentration Taking into account that children below 11 years of age
levels in all 26 blocks of Murshidabad. normally do not show skin lesions, still we expect at least 0.1
This calculation was based on the percentage of hand million would be affected. Based on information supplied by
tubewells in each block that had arsenic above a certain our group of field workers, we had screened 25,274 people
concentration level and the number of users per hand tubewell from 139 arsenic-affected villages in Murshidabad, and 4813
in each block of Murshidabad, which we expected would be (19%) of them were found to have arsenical skin lesions. As
directly proportional. This was considered on the basis of our we surveyed during daytime, a section of adult males were
survey report showing that more than 95% people in the mostly out for work, children were in school, and a section of
Murshidabad district use tubewell water for drinking purposes. village women were too shy to come before us. Still it appears
We have shown the detailed calculation procedure in our that the number of cases we have found is much less than the
earlier publication (16). theoretical prediction. We do not have any definite explana-
tion for this, though the following facts may be responsible for
Estimation of Population That May Suffer from this large difference.
Arsenical Skin Lesions and Cancer by Comparing Now, many villagers are becoming aware of how to
with International Data distinguish between arsenic-contaminated tubewells and safe
Arsenical skin lesions should not be considered simply as ones. Moreover, alternative safe water sources are being
skin disease. The manifestation on skin is the effect of internal installed through government as well as nongovernmental
damage. We compared the estimated arsenic-exposed popu- initiatives in the affected areas. Notably, in estimating the
lation (as obtained from Table 4) with available international affected population, we assumed that arsenic in the water from
data showing the dose-response relationship between arsenic the contaminated hand tubewells was present from the date of
concentration and different health effects such as skin lesions installation, since we could not know the exact time period for
and cancer. We then estimated the population size in the which the tubewells were arsenic contaminated. More
Murshidabad district that may suffer from arsenical skin importantly, we also did not know how long the villagers
lesions and cancers, and the results are presented in Table 5. had been drinking water from arsenic-contaminated tubewells.
From our field experience we observed that villagers normally
did not drink continuously from the same tubewell. Further,
DISCUSSION AND CONCLUSION mostly adult males and children stayed outside their homes for
The magnitude of arsenic calamity seems to be severe from 8 – 12 hours a day and thus could consume water from more
the overall study of groundwater arsenic contamination and its than one source. Four important interrelated factors that
health effect in Murshidabad. Extrapolating the data we needed to be considered for the appearance of the arsenical
generated over 3 years, it was estimated that the population skin lesions but could not be accounted for were: 1) how long
drinking arsenic-contaminated water at above 10 mg/L was 2.5 an individual had been drinking from a contaminated
million out of a total population of 5.3 million in Murshidabad tubewell; 2) how much arsenic-contaminated water one
while that drinking at above 50 mg/L was 1.2 million. During consumed daily (daily dose); 3) the concentration of arsenic
our last 10-year survey of the arsenic-affected districts of West in their drinking water; and 4) their nutritional and health
Bengal, we noticed (8,9) that within a span of 3 –7 years in status. Our previous dose response relation studies (3,16)
some villages, tubewells that had initially been safe (arsenic could not account for these factors, thus making estimate of
< 10 mg/L) became contaminated (arsenic > 50 mg/L) in the population with arsenical skin lesions in the affected villages
course of time. Furthermore, the arsenic concentration in much more difficult. Considering all the above facts, the
many tubewells had increased by as much as five- to 20-fold actual numbers may be much less than the values predicted on
(8,9). A similar trend was observed in the Rajapur village of the basis of our study.
the Murshidabad district (19). Analysis of hair, nail, and urine To date there is no known effective medical treatment for
samples revealed that a large section of population might be those suffering from arsenic toxicity. Some chelating agents
subclinically affected. have been used but they are under further investigation (4).
Table 5 provides a rough estimation of the probable number Meanwhile, the need to provide safe water and nutritious food
of affected population, correlating the dose response data from seems to be the only way to bring recovery for early and mild
literature and the available data from our survey. Though skin lesion cases, according to medical personnel as well as
international results show arsenical skin lesions may develop scientists working in this field (22).ARSENIC CONTAMINATION IN MURSHIDABAD: PART I 833
The per capita available surface water in arsenic-affected subcontinent. What lessons have been learned? Talanta 2002; 58:3 –
areas of West Bengal is about 7000 cubic meters. During the 22.
7. Garai R, Chakraborty AK, Dey SB, Saha KC. Chronic arsenic
monsoons, the average annual rainfall in this region is about poisoning from tubewell water. J Indian Med Assoc 1984; 82(1):34 –
2000 mm. In addition, West Bengal is richly endowed with 35.
other available surface water resources such as wetlands, 8. Sengupta MK, Ahamed S, Hossain MA, Rahman MM, Lodh D, Das B,
flooded river basins, lagoons, ponds, and ox-bow lakes. This De S, Pal B, Roy PK, Chakraborti D. In 5th International Conference on
Arsenic: Developing Country’s Perspective on Health, Water and
available surface water can be tapped as an important source
Environmental Issues, Dhaka, Bangladesh, 2004:3 – 9.
of drinking water provided proper purification measures are 9. Chakraborti D, Basu GK, Biswas BK, Chowdhury UK, Rahman MM,
undertaken. Alternative safe water options such as dug-wells Paul K, Chowdhury TR, Chanda CR, Lodh D. Characterization of
and rainwater harvesting may also be explored with measures arsenic bearing sediments in Gangetic Delta of West Bengal-India. In:
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10. Chatterjee A, Das D, Mandal BK, Chowdhury TR, Samanta G,
nants can still be used. Chakraborti D. Arsenic in ground water in six districts of West Bengal,
Most importantly, educating the villagers in the affected India: the biggest arsenic calamity in the world, Part I. Arsenic species in
areas about the existence, magnitude, danger, sign, symptoms drinking water and urine of the affected people. Analyst 1995; 120:643 –
of the arsenic problem, and importance of cheap, nutritious 650.
food in combating the crisis; training them on issues of water 11. Das D, Chatterjee A, Mandal BK, Samanta G, Chakraborti D. Arsenic in
ground water in six districts of West Bengal, India: the biggest arsenic
management; and lastly, involving the entire community in all calamity in the world, Part II. Arsenic concentration in drinking water,
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UK, Basu GK, Chanda CR, Lodh D, Chakraborti D. Flow injection
ACKNOWLEDGMENTS hydride generation atomic absorption spectrometry for determination of
The authors thank the field workers of School of arsenic in water and biological samples from arsenic affected districts
of West Bengal, India and Bangladesh. Microchem J 1999; 62:174 –
Environmental Studies (SOES), Jadavpur University for their 191.
extensive help in the field survey of the Murshidabad district. 13. Samanta G, Chakraborti D. Flow injection atomic absorption spectrom-
The authors wish to thank all the villagers of Murshidabad for etry for the standardization of arsenic, lead and mercury in environ-
their participation and assistance. Financial support from mental and biological standard reference materials. Frenius J Anal Chem
1997; 357(7):827 – 832.
SOES is greatly acknowledged.
14. Rahman MM, Mukherjee DP, Sengupta MK, Chowdhury UK, Lodh D,
Chanda CR, Roy S, Selim M, Zaman QQ, Milton AH, Sahidulla SM,
Rahman MT, Chakraborti D. Effectiveness and reliability of arsenic
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