Arsenic in groundwater of West Bengal, India: A review of human health risks and assessment of possible intervention options.

Inorganic arsenic induces a variety of toxicities including cancer. The mode of action for cancer and non-cancer effects involves the metabolic generation of trivalent arsenicals and their reaction with sulfhydryl groups within critical proteins in various cell types which leads to the biological response. In epithelial cells, the response is cell death with consequent regenerative proliferation. If this continues for a long period of time, it can result in an increased risk of cancer. Arsenicals do not react with DNA. There is evidence for indirect genotoxicity in various in vitro and in vivo systems, but these involve exposures at cytotoxic concentrations and are not the basis for cancer development. The resulting markers of genotoxicity could readily be due to the cytotoxicity rather than an effect on the DNA itself. Evidence for genotoxicity in humans has involved detection of chromosomal aberrations, sister chromatid exchanges in lymphocytes and micronucleus formation in lymphocytes, buccal mucosal cells, and exfoliated urothelial cells in the urine. Numerous difficulties have been identified in the interpretation of such results, including inadequate assessment of exposure to arsenic, measurement of micronuclei, and potential confounding factors such as tobacco exposure, folate deficiency, and others. Overall, the data strongly supports a non-linear dose response for the effects of inorganic arsenic. In various in vitro and in vivo models and in human epidemiology studies there appears to be a threshold for biological responses, including cancer.

Inorganic arsenic: A non-genotoxic carcinogen.

Millions of people are exposed to arsenic resulting in a range of health implications. This paper provides an up-to-date review of the different sources of arsenic (water, soil, and food), indicators of human exposure (biomarker assessment of hair, nail, urine, and blood), epidemiological and toxicological studies on carcinogenic and noncarcinogenic health outcomes, and risk assessment approaches. The review demonstrates a need for more work evaluating the risks of different arsenic species such as, arsenate, arsenite monomethylarsonic acid, monomethylarsonous acid, dimethylarsinic acid, and dimethylarsinous acid as well as a need to better integrate the different exposure sources in risk assessments.

/pdf/human-health-risk-assessment-for-arsenic-a-critical-review-4qv4bw25vi.pdf

Human health risk assessment for arsenic: A critical review

Safe limit of arsenic in soil in relation to dietary exposure of arsenicosis patients from Malda district, West Bengal- A case study

Heavy metal contamination, major ion chemistry and appraisal of the groundwater status in coastal aquifer, Kalpakkam, Tamil Nadu, India

Few reports are available that characterize daily arsenic exposure through water and diet among people living in groundwater-contaminated regions and correlate it with biomarkers. The present study describes the total individual arsenic exposure and arsenic level in urine and hair of such an arsenic-exposed population in West Bengal. Demographic characteristics and the total daily arsenic intake through water and diet were determined in 167 (Group-1 participants selected from arsenic endemic region) and 69 (Group-2 participants selected from arsenic non-endemic region) in West Bengal. Out of 167 Group-1 participants 78 (Group-1A) had arsenical skin lesions while 89 Group-1B) had no such lesion. Arsenic level in water samples as well as diet, urine and hair samples, collected from all the individual participants, were estimated. The mean value of estimated total arsenic content from water and diet was 349 (range: 20-1615) μg/day in 167 (Group-1) participants living in As endemic region [As in water: mean value 54 (range:BDL-326) μg/L] and 36 (range:12-120) μg/day in 69 (Group-2) participants living in As non-endemic region (As in water: below detection level (BDL), < 0.3 μg/L). Estimated mean arsenic level in urine in these two groups of participants was 116 (range: 6-526) μg/L and 17 (range: BDL-37) μg/L and in hair was 1.0 (range: 0.22-3.98) mg/Kg and 0.16 (range: 0.06-0.37) mg/Kg, respectively. Multiple regressions analysis in Group-1 participants showed that total arsenic intake was associated significantly with urinary and hair arsenic level. The estimated regression coefficient was 0.0022 (95% confidence interval, C.I: 0.0016, 0.0028; P < 0.001) and 0.0024 (95% C.I: 0.0021, 0.003; P < 0.001), respectively. In sub group analysis, higher median urinary arsenic value relative to arsenic intake through water and diet was observed in 78 Group-1A subjects with skin lesion compared to urinary arsenic value in 89 Group-1B subjects without skin lesions, though there was a marginal difference of median total arsenic intake in these two groups. This study showed that significant elevation of arsenic level in urine and hair was associated with elevated arsenic intake through water and diet in people living in arsenic endemic region (Group-1), while these values were low in people living in non-endemic region (Group-2). Those with skin lesions were found to have higher arsenic in urine and hair compared to those without skin lesion with similar arsenic intake through water and diet.

Bhaswati Ganguly

Papers

Evaluation of dietary arsenic exposure and its biomarkers: a case study of West Bengal, India