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Chandan Saha

Bio: Chandan Saha is an academic researcher from Calcutta School of Tropical Medicine. The author has contributed to research in topics: Solvent & Absorption spectroscopy. The author has an hindex of 12, co-authored 41 publications receiving 412 citations.

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TL;DR: Large number of people in the district of Nadia are showing arsenical skin lesion, however, insufficient education, poverty, lack of awareness and ineffective health care support are major factors causing immense plight to severely arsenic affected people.
Abstract: Background: The global health impact and disease burden due to chronic arsenic toxicity has not been well studied in West Bengal. Objective: To ascertain these, a scientific epidemiological study was carried out in a district of the state. Materials and Methods: Epidemiological study was carried out by house-to-house survey of arsenic affected villages in the district of Nadia. A stratified multi-stage design has been adopted for this survey for the selection of the participants. A total number of 2297 households of 37 arsenic affected villages in all the 17 blocks were surveyed in the district. Result: Out of 10469 participants examined, prevalence rate of arsenicosis was found to be 15.43%. Out of 0.84 million people suspected to be exposed to arsenic, 0.14 million people are estimated to be suffering from arsenicosis in the district. Highest level of arsenic in drinking water sources was found to be 1362 μg/l, and in 23% cases it was above 100 μg/l. Majority of the population living in the arsenic affected villages were of low socio-economic condition, inadequate education and were farmers or doing physical labour. Chronic lung disease was found in 207 (12.81%) subjects among cases and 69 (0.78%) in controls. Peripheral neuropathy was found in 257 (15.9%) cases and 136 (1.5%) controls. Conclusion: Large number of people in the district of Nadia are showing arsenical skin lesion. However, insufficient education, poverty, lack of awareness and ineffective health care support are major factors causing immense plight to severely arsenic affected people.

105 citations

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TL;DR: Evidence is shown of increased association of HTN in individuals resident in arsenic endemic region compared to those from a non-endemic region in West Bengal, India, which support an association between arsenic exposure and HTN.
Abstract: Various systemic manifestations are reported to be caused by chronic arsenic exposure in the population living in the Indo-Bangladesh subcontinent. This study from West Bengal assesses the likelihood of occurrence of hypertension (HTN) in individuals resident in an area of high groundwater contamination with arsenic (Nadia district) compared to those from a non-contaminated area (Hoogly district) in West Bengal, India. Two hundred and eight study participants (Group 1) were recruited from a cross-sectional study in six villages in the Nadia district and 100 controls (Group 2) from a village in the Hoogly district. The two groups were evenly matched in regard to age and sex. History taking and clinical examination including blood pressure measurement were undertaken in each participant. Water samples from current and previous drinking water sources and hair and urine samples from each participant were collected for estimation of arsenic. The present study shows evidence of increased association of HTN in individuals resident in arsenic endemic region compared to those from a non-endemic region in West Bengal. There were increased odds ratios for HTN [Adjusted Odds Ratio, OR, 2.87 (95 %CI = 1.26-4.83)] in Group- 1 participants compared to Group- 2 people. Within Group 1, there was no difference in prevalence of HTN between those with and without skin lesion. There was a dose-effect relationship seen with increasing cumulative arsenic exposure and arsenic level in hair and HTN in participants living in arsenic endemic region.The findings reported here support an association between arsenic exposure and HTN. More work is needed to characterize the link further.

43 citations

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TL;DR: 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, while these values were low in people living in non-endemic region (Group-2).
Abstract: 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.

32 citations

Journal ArticleDOI
TL;DR: The structure and dynamics of water under confinement differ drastically from its bulk behavior and show a considerable degree of inhomogeneity due to disruption in its hydrogen bonding (H-bonding) network as mentioned in this paper.
Abstract: The structure and dynamics of water under confinement differ drastically from its bulk behavior and show a considerable degree of inhomogeneity due to disruption in its hydrogen bonding (H-bonding) network. We attempt to probe such a microheterogeneous environment of reverse micelles (RMs) as well as binary mixtures of acetonitrile–water and ethanol–water by a H-bond sensitive probe 5-methoxy-1-keto-1,2,3,4-tetrahydro carbazole (MTC). Photophysical properties (quantum yield, lifetime, λmax) of MTC in the excited states are found to be extremely sensitive to the changes in the H-bonding of its immediate local environment. We observe huge Stoke’s shifts in the λmaxem of MTC with variation in the solvent environment, as we increase the polarity inside the nanopool of RMs and the mole fractions of water in the binary mixtures. We are able to effectively sense the subtle changes in the H-bonding network inside RMs with an increase in w0 and the formation of self-aggregated microclusters inside the binary mixtu...

31 citations

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TL;DR: It is suggested that dietary arsenic intake was a potential pathway of arsenic exposure even where arsenic intake through water was reduced significantly in arsenic endemic region in West Bengal.
Abstract: The authors investigated association of arsenic intake through water and diet and arsenic level in urine in people living in arsenic endemic region in West Bengal supplied with arsenic-safe water (<50 μg L−1). Out of 94 (Group-1A) study participants using water with arsenic level <50 μg L−1, 72 participants (Group-1B) were taking water with arsenic level <10 μg L−1. Multiple regressions analysis conducted on the Group-1A participants showed that daily arsenic dose from water and diet were found to be significantly positively associated with urinary arsenic level. However, daily arsenic dose from diet was found to be significantly positively associated with urinary arsenic level in Group-1B participants only, but no significant association was found with arsenic dose from water in this group. In a separate analysis, out of 68 participants with arsenic exposure through diet only, urinary arsenic concentration was found to correlate positively (r = 0.573) with dietary arsenic in 45 participants with skin les...

29 citations


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TL;DR: The research expands the understanding of the nature of hydrogen bonding by delineating the interaction between hydrogen bonds and photons, thereby providing a basis for excited-state hydrogen bonding studies in photophysics, photochemistry, and photobiology.
Abstract: Because of its fundamental importance in many branches of science, hydrogen bonding is a subject of intense contemporary research interest. The physical and chemical properties of hydrogen bonds in the ground state have been widely studied both experimentally and theoretically by chemists, physicists, and biologists. However, hydrogen bonding in the electronic excited state, which plays an important role in many photophysical processes and photochemical reactions, has scarcely been investigated.Upon electronic excitation of hydrogen-bonded systems by light, the hydrogen donor and acceptor molecules must reorganize in the electronic excited state because of the significant charge distribution difference between the different electronic states. The electronic excited-state hydrogen-bonding dynamics, which are predominantly determined by the vibrational motions of the hydrogen donor and acceptor groups, generally occur on ultrafast time scales of hundreds of femtoseconds. As a result, state-of-the-art femtos...

886 citations

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TL;DR: The effects of arsenic on the human body with a main focus on assorted organ systems with respective disease conditions are outlined and underlying mechanisms of disease development in each organ system due to arsenic have been explored.

601 citations

Journal ArticleDOI
TL;DR: Specific focus is placed on the development of new macrocycle hosts since 2010, coupled with considerations of the underlying principles of supramolecular chemistry as well as analytes of interest and common luminophores.
Abstract: There is great need for stand-alone luminescence-based chemosensors that exemplify selectivity, sensitivity, and applicability and that overcome the challenges that arise from complex, real-world media. Discussed herein are recent developments toward these goals in the field of supramolecular luminescent chemosensors, including macrocycles, polymers, and nanomaterials. Specific focus is placed on the development of new macrocycle hosts since 2010, coupled with considerations of the underlying principles of supramolecular chemistry as well as analytes of interest and common luminophores. State-of-the-art developments in the fields of polymer and nanomaterial sensors are also examined, and some remaining unsolved challenges in the area of chemosensors are discussed.

463 citations

Journal ArticleDOI
TL;DR: Recommendations for community action are presented to accompany the 4 recommendations for individual choices to reduce cancer risk, recognizing that a supportive social and physical environment is indispensable if individuals at all levels of society are to have genuine opportunities to choose healthy behaviors.
Abstract: The American Cancer Society (ACS) publishes the Diet and Physical Activity Guideline to serve as a foundation for its communication, policy, and community strategies and, ultimately, to affect dietary and physical activity patterns among Americans. This guideline is developed by a national panel of experts in cancer research, prevention, epidemiology, public health, and policy, and reflects the most current scientific evidence related to dietary and activity patterns and cancer risk. The ACS guideline focuses on recommendations for individual choices regarding diet and physical activity patterns, but those choices occur within a community context that either facilitates or creates barriers to healthy behaviors. Therefore, this committee presents recommendations for community action to accompany the 4 recommendations for individual choices to reduce cancer risk. These recommendations for community action recognize that a supportive social and physical environment is indispensable if individuals at all levels of society are to have genuine opportunities to choose healthy behaviors. This 2020 ACS guideline is consistent with guidelines from the American Heart Association and the American Diabetes Association for the prevention of coronary heart disease and diabetes as well as for general health promotion, as defined by the 2015 to 2020 Dietary Guidelines for Americans and the 2018 Physical Activity Guidelines for Americans.

300 citations