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.

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The exposure of millions to arsenic contaminated water from hand tube wells is a major concern in many Asiatic countries. Field kits are currently used to classify tube wells as delivering arsenic below 50 microg/L (the recommended limit in developing countries) as safe, painted green or above 50 microg/L, unsafe and painted red. More than 1.3 million tube wells in Bangladesh alone have been tested by field kits. A few million U.S. dollars have already been spent and millions are waiting for the ongoing projects. However, the reliability of the data generated through field kits is now being questioned. Samples from 290 wells were tested by field kits and by a reliable laboratory technique to ascertain the reliability of field kits. False negatives were as high as 68% and false positives up to 35%. A statistical analysis of data from 240 and 394 other wells yielded similar rates. We then analyzed 2866 samples from previously labeled wells and found 44.9% mislabeling in the lower range (<50 microg/L) although mislabeling was considerably reduced in the higher range. Variation of analytical results due to analysts and replicates were pointed out adopting analysis of variance (ANOVA) technique. Millions of dollars are being spent without scientific validation of the field kit method. Facts and figures demand improved, environmentally friendly laboratory techniques to produce reliable data.

Since 1988 we have analyzed 140 150 water samples from tube wells in all 19 districts of West Bengal for arsenic; 48.1% had arsenic above 10 microg/L (WHO guideline value), 23.8% above 50 microg/L (Indian Standard) and 3.3% above 300 microg/L (concentration predicting overt arsenical skin lesions). Based on arsenic concentrations we have classified West Bengal into three zones: highly affected (9 districts mainly in eastern side of Bhagirathi River), mildly affected (5 districts in northern part) and unaffected (5 districts in western part). The estimated number of tube wells in 8 of the highly affected districts is 1.3 million, and estimated population drinking arsenic contaminated water above 10 and 50 microg/L were 9.5 and 4.2 million, respectively. In West Bengal alone, 26 million people are potentially at risk from drinking arsenic-contaminated water (above 10 microg/L). Studying information for water from different depths from 107 253 tube wells, we noted that arsenic concentration decreased with increasing depth. Measured arsenic concentration in two tube wells in Kolkata for 325 and 51 days during 2002-2005, showed 15% oscillatory movement without any long-term trend. Regional variability is dependent on sub-surface geology. In the arsenic-affected flood plain of the river Ganga, the crisis is not having too little water to satisfy our needs, it is the crisis of managing the water.

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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.

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.