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Epidemiological and Spatial Association between Arsenic Exposure via Drinking Water and Morbidity and Mortality: Population based studies in rural Bangladesh
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health, International Maternal and Child Health (IMCH). (International Health)
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The overall aim of this thesis is to evaluate the risk for increased morbidity and mortality due to long-term arsenic exposure via drinking water by use of epidemiological and spatial approaches in studies performed in Matlab, Bangladesh. A total of 166,934 individuals aged 4 years and above were screened for skin lesions in 2002-2003. Another sample of 115,903 adults aged 15 years or more and a third sample of 26,972 pregnancies in 1991-2000 were considered in a historical cohort and an ecological study, respectively, where risk of adult mortality and spatial clusters of foetal loss and infant death were analysed in relation to arsenic exposure.

More than 70% of the tube-wells in the study area exceeded the threshold for arsenic contamination according to the WHO guideline (10 µg/L). The prevalence of arsenic-induced skin lesions was 3/1000 and men had significantly higher prevalence of skin lesions (SMR 158, 95% CI: 133-188) compared to women. There was an increased risk for death in adulthood due to all non-accidental causes (hazards ratio = 1.16, [95% CI 1.06-1.26]) even at a low level of arsenic contamination (10-49 µg/L). Slightly lower risks were observed for death in cancers (1.44 [1.06-1.95]) and infectious diseases (1.30 [1.13-1.49]) at 50-149 µg/L, but for cardiovascular diseases, it was evident (1.23 [1.01-1.51]) from the level 150-299 µg/L. A dose-response relationship was observed for each of these causes.

We identified high and low risk clusters of foetal loss and infant death that coincided with identified high and low clusters of arsenic exposure.

Water arsenic concentration of the reported main water source was significantly correlated with arsenic concentration in urine, which reflects current arsenic intake from all sources (R2=0.41, ρ< 0.0001), and the influence of neighbouring water sources was minimal.

The study findings underlines that the ongoing arsenic exposure has resulted in a series of severe public health consequences in Bangladesh that call for reinforcement in the mitigation efforts. Knowledge about the spatial distribution of exposure and health effects may be of value in that process.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis , 2010. , p. x, 51
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 549
Keywords [en]
Arsenic, tube-well, skin lesion, adult mortality, foetal loss, infant death, cohort, spatial model, Bangladesh
National Category
Public Health, Global Health, Social Medicine and Epidemiology
Research subject
International Health
Identifiers
URN: urn:nbn:se:uu:diva-121788ISBN: 978-91-554-7774-5 (print)OAI: oai:DiVA.org:uu-121788DiVA, id: diva2:306599
Public defence
2010-05-17, Rosénsalen, Akademiska sjukhuset, 751 85 Uppsala, Ingång 95/96 nbv, 09:15 (English)
Opponent
Supervisors
Available from: 2010-04-22 Created: 2010-03-30 Last updated: 2010-04-22Bibliographically approved
List of papers
1. Prevalence of arsenic exposure and skin lesions. A population based survey in Matlab, Bangladesh.
Open this publication in new window or tab >>Prevalence of arsenic exposure and skin lesions. A population based survey in Matlab, Bangladesh.
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2006 (English)In: J Epidemiol Community Health, ISSN 0143-005X, Vol. 60, no 3, p. 242-8Article in journal (Refereed) Published
Identifiers
urn:nbn:se:uu:diva-77563 (URN)16476755 (PubMedID)
Available from: 2006-03-15 Created: 2006-03-15 Last updated: 2018-11-28
2. Arsenic in Drinking Water and Adult Mortality: A Population-based Cohort Study in Rural Bangladesh
Open this publication in new window or tab >>Arsenic in Drinking Water and Adult Mortality: A Population-based Cohort Study in Rural Bangladesh
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2009 (English)In: Epidemiology, ISSN 1044-3983, E-ISSN 1531-5487, Vol. 20, no 6, p. 824-830Article in journal (Refereed) Published
Abstract [en]

BACKGROUND:: Arsenic is a potent human carcinogen and toxicant. Elevated concentration of arsenic in drinking water is a major public-health problem worldwide. We evaluated risks of adult mortality (due to cancer and cardiovascular and infectious diseases) in relation to arsenic exposure through drinking water. METHODS:: A cohort analysis was applied to survival data prospectively collected during 1991-2000 in a health and demographic surveillance system in Matlab, Bangladesh, where tubewells were installed beginning in the early 1970s. A total of 115,903 persons aged 15 or more years on 1 January 1991 were available for analysis. In this period, 9015 people died and 22,488 were lost to follow-up. Arsenic exposure data were derived from a survey in 2002-2003 of past and current water use and arsenic concentrations in all tubewells. We estimated risk of excess mortality in relation to arsenic exposure, using proportional hazards models. RESULTS:: Even at low levels (10-49 mug/L) of arsenic in drinking water, we observed increased risk of death due to all nonaccidental causes (hazard ratio = 1.16 [95% confidence interval = 1.06-1.26]). Increased risks at exposure of 50-149 mug/L were observed for death due to cancers (1.44 [1.06-1.95]), cardiovascular disease (1.16 [0.96-1.40]), and infectious diseases (1.30 [1.13-1.49]). We observed clear dose-response relationships for each of these causes. CONCLUSIONS:: Arsenic exposure through drinking water has generated excess adult mortality after 20-30 years of exposure.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-109016 (URN)10.1097/EDE.0b013e3181bb56ec (DOI)000270874000008 ()19797964 (PubMedID)
Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13Bibliographically approved
3. Spatial patterns of fetal loss and infant death in an arsenic-affected area in Bangladesh
Open this publication in new window or tab >>Spatial patterns of fetal loss and infant death in an arsenic-affected area in Bangladesh
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2010 (English)In: International Journal of Health Geographics, ISSN 1476-072X, E-ISSN 1476-072X, Vol. 9, p. 53-Article in journal (Refereed) Published
Abstract [en]

Background: Arsenic exposure in pregnancy is associated with adverse pregnancy outcome and infant mortality. Knowledge of the spatial characteristics of the outcomes and their possible link to arsenic exposure are important for planning effective mitigation activities. The aim of this study was to identify spatial and spatiotemporal clustering of fetal loss and infant death, and spatial relationships between high and low clusters of fetal loss and infant death rates and high and low clusters of arsenic concentrations in tube-well water used for drinking.Methods: Pregnant women from Matlab, Bangladesh, who used tube-well water for drinking while pregnant between 1991 and 2000, were included in this study. In total 29,134 pregnancies were identified. A spatial scan test was used to identify unique non-random spatial and spatiotemporal clusters of fetal loss and infant death using a retrospective spatial and spatiotemporal permutation and Poisson probability models.Results: Two significant clusters of fetal loss and infant death were identified and these clusters remained stable after adjustment for covariates. One cluster of higher rates of fetal loss and infant death was in the vicinity of the Meghna River, and the other cluster of lower rates was in the center of Matlab. The average concentration of arsenic in the water differed between these clusters (319 μg/L for the high cluster and 174 μg/L for the low cluster). The spatial patterns of arsenic concentrations in tube-well water were found to be linked with the adverse pregnancy outcome clusters. In the spatiotemporal analysis, only one high fetal loss and infant death cluster was identified in the same high cluster area obtained from purely spatial analysis. However, the cluster was no longer significant after adjustment for the covariates.Conclusion: The finding of this study suggests that given the geographical variation in tube-well water contamination, higher fetal loss and infant deaths were observed in the areas of higher arsenic concentrations in groundwater. This illustrates a possible link between arsenic contamination in tube-well water and adverse pregnancy outcome. Thus, these areas should be considered a priority in arsenic mitigation programs.

Keywords
arsenic exposure, drinking-water, fetal loss, infant death, spatial clustering, Bangladesh
National Category
Public Health, Global Health, Social Medicine and Epidemiology Geology
Research subject
Epidemiology; Earth Science with specialization in Environmental Analysis; International Health
Identifiers
urn:nbn:se:uu:diva-121780 (URN)10.1186/1476-072X-9-53 (DOI)000284357300001 ()20977746 (PubMedID)
Available from: 2010-03-30 Created: 2010-03-30 Last updated: 2018-11-28Bibliographically approved
4. Spatial modelling of individual arsenic exposure via well water: Evaluation of arsenic in urine, main water source and influence of neighbourhood water sources in rural Bangladesh
Open this publication in new window or tab >>Spatial modelling of individual arsenic exposure via well water: Evaluation of arsenic in urine, main water source and influence of neighbourhood water sources in rural Bangladesh
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2010 (English)In: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 12, no 6, p. 1341-1348Article in journal (Refereed) Published
Abstract [en]

Arsenic concentrations in well water often vary even within limited geographic areas. This makes it difficult to obtain valid estimates of the actual exposure, as people may take their drinking water from different wells. We evaluated a spatial model for estimation of the influence of multiple neighbourhood water sources on the actual exposure, as assessed by concentrations in urine in a population in rural Bangladesh. In total 1,307 individuals  were randomly selected. Arsenic concentrations of urine and water were analysed. Simple average and inverse distance weighted average of arsenic concentrations in the five nearest water sources were calculated for each individual. Spatial autocorrelation was evaluated using Moran’s I statistics, and spatial regression models were employed to account for spatial autocorrelation. The average distance from a household to the nearest tube-well was 32 meters (Inter Quartile Range 1-49 meters). Water arsenic concentrations of the reported main water sources were significantly correlated with concentrations in urine (R2=0.41, ρ< 0.0001, R2 for women=0.45 and for men=0.36). General model fit improved only slightly after spatial adjustment for neighbouring water sources (pseudo R2=0.53, spatial lag model), compared to covariate adjusted regression coefficient (R2=0.46). Arsenic concentration in urine was higher than arsenic in main water source with an intercept of 57µg/L, indicating exposure from food. A suitable way of estimating an individual’s past exposure to arsenic in this rural setting, where influence of neighbouring water sources was minimal, was to consider the reported main source of drinking water.

Keywords
arsenic exposure, urine, drinking-water, spatial model, Bangladesh
National Category
Medical and Health Sciences
Research subject
Epidemiology
Identifiers
urn:nbn:se:uu:diva-121795 (URN)10.1039/C001708F (DOI)000278588400015 ()20390220 (PubMedID)
Available from: 2010-03-30 Created: 2010-03-30 Last updated: 2018-11-28Bibliographically approved

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