Food as medicine: Selenium enriched lentils offer relief against chronic arsenic poisoning in Bangladesh.

Chronic arsenic (As) exposure is a major environmental threat to human health affecting >100 million people worldwide. Low blood selenium (Se) increases the risk of As-induced health problems. Our aim was to reduce As toxicity through a naturally Se-rich lentil diet. In a randomized, double-blind, placebo-control trial in Bangladesh, 405 participants chronically exposed to As were enrolled. The intervention arm (Se-group) consumed Se-rich lentils (55 µg Se/day); the control arm received lentils of similar nutrient profile except with low Se (1.5 µg Se/day). Anthropometric measurements, blood, urine and stool samples, were taken at baseline, 3 and 6 months; hair at baseline and 6 months after intervention. Morbidity data were collected fortnightly. Measurements included total As in all biological samples, As metabolites in urine, and total Se in blood and urine. Intervention with Se-rich lentils resulted in higher urinary As excretion (p = 0.001); increased body mass index (p ≤ 0.01), and lower incidence of asthma (p = 0.05) and allergy (p = 0.02) compared to the control group. The Se-group demonstrated increased excretion of urinary As metabolite, dimethylarsinic acid (DMA) at 6 months compared to control group (p = 0.008). Consuming Se-rich lentils can increase As excretion and improve the health indicators in the presence of continued As exposure.

An overview of plant-based interventions to ameliorate arsenic toxicity.

The industrial and technological advancements in the world have also contributed to the rapid deterioration in the environment quality through introduction of obnoxious pollutants that threaten to destroy the subtle balance in the ecosystem. The environment contaminants cause severe adverse effects to humans, flora and fauna that are mostly irreversible. Chief among these toxicants is arsenic, a metalloid, which is considered among the most dangerous environmental toxins that leads to various diseases which affect the quality of life even when present in small quantities. Treatment of arsenic-mediated disorders still remains a challenge due to lack of effective options. Chelation therapy has been the most widely used method to detoxify arsenic. But this method is associated with deleterious effects leading various toxicities such as hepatotoxicity, neurotoxicity and other adverse effects. It has been discovered that indigenous drugs of plant origin display effective and progressive relief from arsenic-mediated toxicity without any side-effects. Further, these phytochemicals have also been found to aid the elimination of arsenic from the biological system and therefore can be more effective than conventional therapeutic agents in ameliorating arsenic-mediated toxicity. This review presents an overview of the toxic effects of arsenic and the therapeutic strategies that are available to mitigate the toxic effects with emphasis on chelation as well as protective and detoxifying activities of different phytochemicals and herbal drugs against arsenic. This information may serve as a primer in identifying novel prophylactic as well as therapeutic formulations against arsenic-induced toxicity.

Risk of ingesting As, Cd, and Pb in animal products in north Rio de Janeiro state, Brazil.

This study evaluated the levels of As, Cd, and Pb in muscle and liver the cattle and chicken. The risk was estimated for the adult population of a midsized city in southeast Brazil, concerning the tolerable ingestion and cancer risk. Samples of muscle and liver (cattle and chicken) were collected (n = 250). Samples of mineral supplements for cattle (n = 4) and chicken feed samples (n = 4) were evaluated as one of many potential source of contamination. Muscle, liver, mineral supplement, and feed samples were dissolved in acid medium and analyzed by ICP-OES. Daily muscle and liver intake was estimated using a questionnaire (N = 427). Daily intake of trace elements by the population based on the consumption of cattle muscle, cattle liver, chicken muscle, and chicken liver was low, corresponding to 2.76%, 0.33%, 2.12%, and 0.22% of the Tolerable Intake defined by the WHO for As; 0.54%, 0.29% 0.55%, 0.01%, for Cd; and 0.80%, 0.07%, 0.62%, 0.02%, for Pb. The mean of total ingestion of As, Cd and Pb was 5.43%, 1.18% and 1.51%, respectively of Tolerable Intake defined by WHO. Cancer risk was lower than 5 × 10-5 year-1. The results indicate that the muscle and liver consumption is a source of As, Cd, and Pb. Consumers that ingest cattle and chicken muscle need attention in terms the risk of cancer related to intake of As and Cd. Feed and mineral supplementation remain as one of many sources of exposure of As, Cd, and Pb.

Discontinuity in the cancer slope factor as it passes from high to low exposure levels--arsenic in the BFD-endemic area.

BACKGROUND: The ingestion of inorganic arsenic causes bladder and lung cancers demonstrably at >400-500ug/L but questionably below 100-200ug/L. Using the standard 42-village cancer mortality dataset from the Blackfoot-disease (BFD) endemic area of southwest Taiwan (Wu et al., 1989), we examined the risk from low exposures by excluding the high exposures. METHOD: Poisson regression analyses with the sequential removal of the highest exposure village have been performed using the median, mean, or maximum village well water arsenic level and demonstrated graphically. RESULTS: Risk estimates are positive when villages with exposures of 200-400ug/L are included and significantly so when villages with >400ug/L are included. Risk estimates for exposures below 100ug/L are negative but rarely significantly so. The inflection point where the slope is no longer positive occurs in the range of 100-200ug/L, depending upon whether the exposure metric used is the median, the mean or the maximum. CONCLUSION: There is a discontinuity in the cancer slope factor or risk from arsenic exposure that occurs in the range of 100-200ug/L. Above these levels, there are significantly positive risks, while below these levels there are not. The analysis reveals within this dataset an intrinsic non-linearity in the cancer risk. The literature speaks to this discontinuity, but this is the first demonstration within a single dataset that shows the discontinuity across the full exposure range and where the low-dose data are not compromised with high-dose data.

[The regulation mechanism of protein kinase Cδ on arsenic liver injury caused by coal-burning].

OBJECTIVE: To investigate the effects of mRNA transcriptional and protein expressions of protein kinase Cδ (PKCδ) on the development of arsenic liver injury caused by coal-burning. METHODS: Population study:133 arsenic exposures were selected as arsenic exposure groups including the ward non-patient group (25 cases) , no obvious hepatopathy group (38 cases) , mild (43 cases) and moderate to severe hepatopathy group (27 cases) from the area with endemic arsenism in Guizhou province. Another 34 healthy residents were selected as the control group in non-arsenic pollution village. The urine and peripheral blood were collected from the subjects. The arsenic contents in urine and mRNA expressions of PKCδ in peripheral blood were detected. Animal experiment study:thirty wistar rats were randomly by random number table divided into control group, drinking water arsenic poisoning group and coal-burning arsenic poisoning group (i.e., low, medium and high arsenic contaminated grain group) by random number table method, including 6 rats in each group. The control group was fed normally for 3 months, drinking water arsenic poisoning group and coal-burning arsenic poisoning groups were fed respectively with 10 mg/kg As2O3 solution and different concentrations (25, 50 and 100 mg/kg) of arsenic-containing feed which was persisted 3 months. The arsenic contents in urine, mRNA expression levels of PKCδ in peripheral blood and liver tissue and the protein expression levels of phosphorylated protein kinase Cδ(pPKCδ) in liver tissue were detected. RESULTS: The median(quartile) of arsenic contents in urine were 25.58 (18.62-40.73), 56.66 (38.93-76.77), 64.90 (39.55- 98.37) and 75.47 (41.30-109.70) µg/g Cr respectively for the non-patient group, no obvious hepatopathy group, mild and moderate to severe hepatopathy group. The levels were higher than that in the control group (23.34 (17.84-37.45) µg/g Cr) (P < 0.05), except for the ward non-patient group. The arsenic contents in rat urine were 2223.61 (472.98-3976.73), 701.16 (194.01-1300.27), 1060.94 (246.33-2585.47) and 3101.11 (1919.97-5407.07) µg/g Cr, respectively for the drinking water arsenic poisoning group, the low, medium and high dosage arsenic grain contamination groups, all higher than that in the control group (94.32 (22.65-195.25) µg/g Cr) (P < 0.05) . The protein expressions of pPKCδ in liver tissue were 324.83 ± 25.06, 278.50 ± 30.57, 308.83 ± 34.67 and 326.33 ± 35.09, which were significantly higher than that in the control group (240.17 ± 28.07) (P < 0.05) . The protein expression levels of pPKCδ in liver cell membrane were 0.49 ± 0.06,0.33 ± 0.05,0.37 ± 0.06 and 0.50 ± 0.08, which were significantly higher than that in the control group (0.28 ± 0.04) (P < 0.05) . The protein expression levels of pPKCδ in liver cell cytoplasm were 0.38 ± 0.06,0.31 ± 0.05, 0.35 ± 0.05 and 0.36 ± 0.05, which were significantly higher than that in the control group (0.24 ± 0.05) (P < 0.05). CONCLUSION: The arsenic may regulate protein expressions of pPKCδ and induce its membrane translocation, and cause the development of arsenic liver injury caused by coal-burning.

Hair arsenic levels and prevalence of arsenicosis in three Cambodian provinces.

Natural, inorganic arsenic contamination of groundwater threatens the health of more than 100 million people worldwide, including residents of the densely populated river deltas of South and Southeast Asia. Contaminated groundwater from tube wells in Cambodia was discovered in 2001 leading to the detection of the first cases of arsenicosis in 2006. The most affected area was the Kandal Province. The main objective of this study was to determine the prevalence of arsenicosis in Cambodia based on acceptable criteria, and to investigate the use of hair arsenic as a biomarker not only for arsenicosis-related signs but also for associated symptoms. A cross-sectional epidemiological study of 616 respondents from 3 purposely selected provinces within the Mekong River basin of Cambodia was conducted. The Kandal Province was chosen as a high arsenic-contaminated area, while the Kratie Province and Kampong Cham Province were chosen as moderate and low arsenic-contaminated areas, respectively. The most prevalent sign of arsenicosis was hypomelanosis with a prevalence of 14.5% among all respondents and 32.4% among respondents with a hair arsenic level of ≥1 µg/g. This was followed by hyperkeratosis, hyperpigmentation and mee's lines. Results also suggest a 1.0 µg/g hair arsenic level to be a practical cut off point for an indication of an arsenic contaminated individual. This hair arsenic level, together with the presence of one or more of the classical signs of arsenicosis, seems to be a practical criteria for a confirmed diagnosis. Based on these criteria, the overall prevalence of arsenicosis for all provinces was found to be 16.1%, with Kandal Province recording the highest prevalence of 35.5%. This prevalence is comparatively high when compared to that of other affected countries. The association between arsenicosis and the use of Chinese traditional medicine also needs further investigation.

Chronic arsenic exposure and its adverse health effects in Taiwan: a paradigm for management of a global environmental problem.

It was estimated that, nearly 100 million people are at risk for drinking arsenic (As)-contaminated drinking water. Although the WHO guideline recommends that levels of As in drinking water should not exceed 10 µm/L, it was estimated that more than 30 million people drink As-containing water at levels more than 50 µm/L in Bangladesh and India alone. Therefore, the adverse health effects resulting from chronic As exposure pose a global threat. In Taiwan, studies focusing on the health effects resulting from chronic As exposure through contaminated drinking water have been ongoing for more than 50 years. During the past half century, it was recognized that the impact of high As exposure on human health is much more complicated than originally anticipated. Chronic As exposure resulted in infamous blackfoot disease, which is unique to As endemic areas in Taiwan, and various diseases including cancers and non-cancers. Although the potential-biological outcomes have been well-documented, the pathomechanisms leading from As exposure to occurrence and development of the diseases remain largely unclear. One of the major obstacles that hindered further understanding regarding the adverse health effect resulting from chronic As exposure is documentation of cumulative As exposure from the distant past, which remains difficult as the present technologies mostly document relatively recent As exposure. Furthermore, the susceptibility to As exposure appears to differ between different ethnic groups and individuals and is modified by lifestyle factors including smoking habits and nutrition status. No consensus data has yet been reached even after comparing the study results obtained from different parts of the world focusing on associations between human As toxicity and genetic polymorphisms in terms of cellular detoxification enzymes, tumor suppressor proteins, and DNA repair pathway. With the availability of the new powerful "OMIC" technologies, it may now be possible to gain new path-breaking insights regarding this important environmental health issue. The lessons learned from the past half-century placed Taiwan in an experienced position to actively participate in the international collaborative projects using these novel technologies and standardized methods.

An interview with Mahmuder Rahman: Bangladesh's arsenic agony.

Professor Mahmuder Rahman obtained his medical degree from Dhaka University in Bangladesh and is a member of the Royal College of Physicians (United Kingdom). He was a full professor and consultant physician at Dhaka National Medical College and Hospital until 2003. Apart from his clinical and academic work, he has contributed extensively to formulating policy for affordable health services, and is actively involved in developing integrated health delivery services such as Dhaka Community Hospital, which is a self-financing hospital dedicated to providing health care for people on low incomes. Rahman was actively involved in developing the "Arsenicosis" National Case Detection and Case Management Protocols. He has published more than 15 papers on Bangladesh's arsenic problem. As a member of Bangladesh's National Expert Committee on Arsenic, he took a leading role in formulating the National Arsenic Mitigation Policy and Action Plan.

Epidemiology and prevention of chronic arsenicosis: an Indian perspective.

Arsenicosis is a global problem but the recent data reveals that Asian countries, India and Bangladesh in particular, are the worst sufferers. In India, the state of West Bengal bears the major brunt of the problem, with almost 12 districts presently in the grip of this deadly disease. Recent reports suggest that other states in the Ganga/Brahmaputra plains are also showing alarming levels of arsenic in ground water. In West Bengal, the majority of registered cases are from the district of Nadia, and the maximum number of deaths due to arsenicosis is from the district of South 24 Paraganas. The reason behind the problem in India is thought to be mainly geogenic, though there are instances of reported anthropogenic contamination of arsenic from industrial sources. The reason for leaching of arsenic in ground water is attributed to various factors, including excessive withdrawal of ground water for the purpose of irrigation, use of bio-control agents and phosphate fertilizers. It remains a mystery why all those who are exposed to arsenic-contaminated water do not develop the full-blown disease. Various host factors, such as nutritional status, socioeconomic status, and genetic polymorphism, are thought to make a person vulnerable to the disease. The approach to arsenicosis mitigation needs be holistic, sustainable, and multidisciplinary, with the 2 main pillars being health education and provision of 'arsenic-free water.' In the state of West Bengal, the drive for arsenic mitigation has been divided into 3 phases using various methods, including new hand pumps/tube wells at alternative deep aquifers, dug wells, arsenic removal plants, arsenic treatment units, as well as piped and surface water supply schemes. The methods have their own limitations, so it is intended that a pragmatic approach be followed in the arsenicosis prevention drive. It is also intended that the preventive measures be operationally and economically feasible for the people living in the affected areas.

Association between arsenic exposure from drinking water and plasma levels of soluble cell adhesion molecules.

BACKGROUND: Epidemiologic studies of cardiovascular disease risk factors and appropriate biomarkers in populations exposed to a wide range of arsenic levels are a public health research priority. OBJECTIVE: We investigated the relationship between inorganic arsenic exposure from drinking water and plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular adhesion molecule-1 (sVCAM-1), both markers of endothelial dysfunction and vascular inflammation, in an arsenic-exposed population in Araihazar, Bangladesh. METHODS: The study participants included 115 individuals with arsenic-related skin lesions participating in a 2 x 2 randomized, placebo-controlled, double-blind trial of vitamin E and selenium supplementation. Arsenic exposure status and plasma levels of sICAM-1 and sVCAM-1 were assessed at baseline and after 6 months of follow-up. RESULTS: Baseline well arsenic, a long-term measure of arsenic exposure, was positively associated with baseline levels of both sICAM-1 and sVCAM-1 and with changes in the two markers over time. At baseline, for every 1-mug/L increase in well arsenic there was an increase of 0.10 ng/mL [95% confidence interval (CI), 0.00-0.20] and 0.33 ng/mL (95% CI, 0.15-0.51) in plasma sICAM-1 and sVCAM-1, respectively. Every 1-microg/L increase in well arsenic was associated with a rise of 0.11 ng/mL (95% CI, 0.01-0.22) and 0.17 ng/mL (95% CI, 0.00-0.35) in sICAM-1 and sVCAM-1 from baseline to follow-up, respectively, in spite of recent changes in urinary arsenic as well as vitamin E and selenium supplementation during the study period. CONCLUSIONS: The findings indicate an effect of chronic arsenic exposure from drinking water on vascular inflammation that persists over time and also suggest a potential mechanism underlying the association between arsenic exposure and cardiovascular disease.

Health effects of exposure to natural arsenic in groundwater and coal in China: an overview of occurrence.

Between 2001 and 2005, 21,155 of 445,638 wells in 20,517 villages in 292 counties in 16 provinces from China, or 5% of wells, were found to contain > 50 microg/L arsenic (As) by field testing with the Merck As kit. We achieved quality assurance of analysis of at least 10% of the wells containing > 50 microg/L As using hydride generation atomic fluorescence spectrometry and silver dithiodicarbomate spectrometry. Our best estimate of the population exposed to > 50 microg/L As in drinking water was 582,769. This is probably an underestimate for China because of the limited area surveyed. In a survey of 135,492 individuals in eight provinces, we used the National Diagnosis Standard for Endemic Arsenicosis and identified 10,096 cases of arsenicosis with various degrees of skin lesions. The arsenicosis occurrence rate of 7.5% is likely an overestimate, because the survey focused more on known and suspected endemic areas of arsenicosis. The occurrence of arsenicosis correlates positively with the percentage of wells containing > 50 microg/L As, or at a ratio of 1 to 5%. Based on both the amount of As in well water and the rate of occurrence of arsenicosis, Shanxi province, Inner Mongolia autonomous region, and Jilin province are the top three areas in China as of 2005 for exposure to endemic As from drinking water. Our survey also identified exposure to high levels of As from wells in several provinces and from the indoor burning of coal containing high levels of As in Shaanxi province. These areas, however, have not had any reports of previous arsenicosis endemics. In the endemic areas, the average rate of occurrence of arsenicosis at advanced stages was 1.2%, possibly because of a long exposure time of > 20 years; the rate of occurrence increased to 2.7% when we included a high dose of As exposure from the indoor burning of coal. Mitigation to reduce As exposure remains a challenge in rural China.

Water consumption patterns in rural Bangladesh: are we underestimating total arsenic load?

Risk related to the ingestion of any water contaminants depends on many factors, including the daily per capita amount of consumed water relative to body weight. This study explored the water consumption pattern of a rural arsenic-affected population in Bangladesh. The study findings are likely to contribute to the risk estimation attributable to ingestion of arsenic and other drinking water contaminants. A total of 640 individuals participated in this cross-sectional study carried out in an arsenic-affected rural population in Bangladesh. In this study daily per capita water consumption for drinking purposes was found to be 73.04 ml/kg/d (range = 71.24-74.84 ml/kg/d), which is higher than for both the US and Taiwan populations. This difference in per capita drinking water consumption might contribute to much higher lifetime cancer mortality and other morbidity risks from arsenic among the Bangladesh population compared to either the US or Taiwan populations. Arsenic is also ingested through cooking water which, if considered, might increase the risk further. The findings of this study highlight the urgent need for a holistic water supply programme for Bangladesh, with special emphasis on the arsenic-affected population.

Cryptic exposure to arsenic.

Arsenic is an odorless, colorless and tasteless element long linked with effects on the skin and viscera. Exposure to it may be cryptic. Although human intake can occur from four forms, elemental, inorganic (trivalent and pentavalent arsenic) and organic arsenic, the trivalent inorganic arsenicals constitute the major human hazard. Arsenic usually reaches the skin from occupational, therapeutic, or environmental exposure, although it still may be employed as a poison. Occupations involving new technologies are not exempt from arsenic exposure. Its acute and chronic effects are noteworthy. Treatment options exist for arsenic-induced pathology, but prevention of toxicity remains the main focus. Vitamin and mineral supplementation may play a role in the treatment of arsenic toxicity.

Evaluation of biochemical changes in chronic arsenic poisoning among Bangladeshi patients.

An estimated 40 million people in Bangladesh have been suffering from arsenic toxicity-related diseases because of drinking water contamination with high levels of naturally occurring arsenic. To evaluate the biochemical changes in chronic arsenic exposure, a total of 115 exposed subjects diagnosed as arsenicosis patients were examined and interviewed, and 120 unexposed volunteers were enrolled in this study. Drinking water, urine and peripheral blood samples were collected from all participants and analyzed. The average levels of arsenic in the drinking water and spot urine samples of the arsenicosis patients were 218.1 microg/L and 234.6 microg/L, respectively, and duration of exposure was 7.6 +/- 5.2 yrs that ranged from 1-25 yrs. Prevalence of diabetes mellitus among chronic arsenic-exposed subjects was about 2.8 times higher than the unexposed subjects. The activities of alkaline phosphatase were significantly elevated in the patients, 197 U/L compared to 149 U/L in the controls, but alanine transaminase and aspartate transaminase were mostly normal. The patients had significantly lower levels of serum creatinine, 0.97 mg/dL compared to 1.15 mg/dL in the controls; but had significantly elevated levels of total protein, 84 g/L and 77 g/L respectively. The mean level of inorganic phosphate in the serum of arsenicosis patients was 6.4 mg/dL compared to 4.6 mg/dL in the unexposed subjects and the level was significantly higher, indicating substitution of the pentavalent arsenate for the phosphate ion causing underutilization of the latter. Evaluation of the lipid profiles showed while the levels of triacylglycerol were not much different, the patients had significantly lower levels of cholesterol, HDL-cholesterol and LDL-cholesterol compared to the unexposed subjects. These findings suggest significant changes in biochemical parameters in human arsenic toxicity.

Heavy metal content of ayurvedic herbal medicine products.

CONTEXT: Lead, mercury, and arsenic intoxication have been associated with the use of Ayurvedic herbal medicine product (HMPs). OBJECTIVES: To determine the prevalence and concentration of heavy metals in Ayurvedic HMPs manufactured in South Asia and sold in Boston-area stores and to compare estimated daily metal ingestion with regulatory standards. DESIGN AND SETTING: Systematic search strategy to identify all stores 20 miles or less from Boston City Hall that sold Ayurvedic HMPs from South Asia by searching online Yellow Pages using the categories markets, supermarkets, and convenience stores, and business names containing the word India, Indian cities, and Indian words. An online national directory of Indian grocery stores, a South Asian community business directory, and a newspaper were also searched. We visited each store and purchased all unique Ayurvedic HMPs between April 25 and October 24, 2003. MAIN OUTCOME MEASURES: Concentrations (microg/g) of lead, mercury, and arsenic in each HMP as measured by x-ray fluorescence spectroscopy. Estimates of daily metal ingestion for adults and children estimated using manufacturers' dosage recommendations with comparisons to US Pharmacopeia and US Environmental Protection Agency regulatory standards. RESULTS: A total of 14 (20%) of 70 HMPs (95% confidence interval, 11%-31%) contained heavy metals: lead (n = 13; median concentration, 40 microg/g; range, 5-37,000), mercury (n = 6; median concentration, 20,225 microg/g; range, 28-104,000), and/or arsenic (n = 6; median concentration, 430 microg/g; range, 37-8130). If taken as recommended by the manufacturers, each of these 14 could result in heavy metal intakes above published regulatory standards. CONCLUSIONS: One of 5 Ayurvedic HMPs produced in South Asia and available in Boston South Asian grocery stores contains potentially harmful levels of lead, mercury, and/or arsenic. Users of Ayurvedic medicine may be at risk for heavy metal toxicity, and testing of Ayurvedic HMPs for toxic heavy metals should be mandatory.

Determination of urinary trace elements (arsenic, copper, cadmium, manganese, lead, zinc, selenium) in patients with Blackfoot disease.

To determine the relationship of arsenic, copper, cadmium, manganese, lead, zinc and selenium to Blackfoot disease (BFD, a peripheral vascular disorder endemic to areas of Taiwan, which has been linked to arsenic in drinking water) the authors measured the amount of these substances in urine from BFD patients, using atomic absorption spectrometry. Results indicate significantly higher amounts of urinary arsenic, copper, cadmium, manganese, and lead for BFD patients than for normal controls, also significantly lower urinary zinc and selenium.

High arsenic groundwater: mobilization, metabolism and mitigation--an overview in the Bengal Delta Plain.

The widespread occurrence of high inorganic arsenic in natural waters is attributed to human carcinogen and is identified as a major global public health issue. The scale of the problem in terms of population exposure (36 million) and geographical area coverage (173 x 10(3) Km2) to high arsenic contaminated groundwater (50-3200 microgL(-1)) compared to the National drinking water standard (50 microgL(-1)) and WHO recommended provisional limit (10 microgL(-1)) is greatest in the Holocene alluvium and deltaic aquifers of the Bengal Delta Plain (Bangladesh and West Bengal, India). This large-scale 'natural' high arsenic groundwater poses a great threat to human health via drinking water. Mobilization, metabolism and mitigation issues of high arsenic groundwater are complex and need holistic approach for sustainable development of the resource. Mobilization depends on the redox geochemistry of arsenic that plays a vital role in the release and subsequent transport of arsenic in groundwater. Metabolism narrates the biological response vis-à-vis clinical manifestations of arsenic due to various chemical and biological factors. Mitigation includes alternative source for safe drinking water supply. Drinking water quality regulatory standards as well as guidelines are yet to cover risk assessments for such metal toxicity. Lowering of the ingested inorganic arsenic level and introduction of newer treatment options (implementation of laterite, the natural material) to ensure safe water supply (arsenic free and/or low arsenic within permissible limit) are the urgent need to safe guard the mass arsenic poisoning and internal arsenic related health problems.

Chronic arsenic toxicity: clinical features, epidemiology, and treatment: experience in West Bengal.

Chronic arsenic toxicity due to drinking arsenic-contaminated water has been one of the worst environmental health hazards affecting eight districts of West Bengal since the early eighties. Detailed clinical examination and investigation of 248 such patients revealed protean clinical manifestations of such toxicity. Over and above hyperpigmentation and keratosis, weakness, anaemia, burning sensation of eyes, solid swelling of legs, liver fibrosis, chronic lung disease, gangrene of toes, neuropathy, and skin cancer are some of the other manifestations. A cross-sectional survey involving 7683 participants of all ages was conducted in an arsenic-affected region between April 1995 and March 1996. Out of a population of 7683 surveyed, 3467 and 4216 people consumed water containing As below and above 0.05 mg/L, respectively. Except pain abdomen the prevalence of all other clinical manifestations tested (e.g., pigmentation, keratosis, hepatomegaly, weakness, nausea, lung disease and neuropathy) were found to be significantly higher in As exposed people (water As > 0.05 mg/L) compared to control population (water As level < 0.05 mg/L). The prevalence of pigmentation and keratosis, hepatomegaly, chronic respiratory disease and weakness rose significantly with increasing arsenic concentrations in drinking water. The respiratory effects were most pronounced in individuals with high arsenic water concentrations who also had skin lesion. Therapy with chelating agent DMSA was not found to be superior to placebo effect. However, therapy with DMPS caused significant improvement of clinical condition of chronic arsenicosis patients as evidenced by significant reduction of total clinical scores from 8.90 +/- 2.84 to 3.27 +/- 1.73; p < 0.0001. Efficacy of specific chelation therapy for patients suffering from chronic As toxicity has further need to be fully substantiated. However, supportive treatment could help in reducing many symptoms of the patients. Treatment in hospital with good nutritious diet has been found to reduce symptom score in a subset of placebo treated patients in West Bengal during the course of DMSA and DMPS trial. People should be advised to stop drinking As contaminated water or exposure to As from any other source. The various clinical manifestations should be treated symptomatically.