Tag Archives: Bangladesh

Sea-level rapidly rising, not!

Nils-Axel Mörner, Biology and Shore Morphology: Keys to proper reconstruction of sea level changes, J Marine Biology and Aquascape . Doi: http://dx.doi.org/ 10.31579/ 26415143/JMBA.2019 /020

Biological criteria and shore morphology do not lie. Therefore, they are key elements for a proper reconstruction of sea level changes during the last 500 years. The elements have to be observed, understood, documented and dated. Having done so in the Maldives, Bangladesh, Goa (India), Fiji and New Caledonia, a new picture emerged. Sea level is not at all in a rapidly rising mode in the equatorial region, rather it is in opposed phase with the well-known climate changes of the Northern Hemisphere. The main driving force is changes in Earth’s rate of rotation as a function of planetary-solar interaction with the Earth’s systems.

Taste Detection and Acceptability for Chlorine Residual, Bangladesh

Crider Y, Sultana S, Unicomb L, Davis J, Luby SP, Pickering AJ. Can you taste it? Taste detection and acceptability thresholds for chlorine residual in drinking water in Dhaka, Bangladesh. The Science of the total environment. 2017 Sep 20;613-614:840-846. doi: 10.1016/j.scitotenv.2017.09.135.

Chlorination is a low-cost, effective method for drinking water treatment, but aversion to the taste or smell of chlorinated water can limit use of chlorine treatment products. Forced choice triangle tests were used to evaluate chlorine detection and acceptability thresholds for two common types of chlorine among adults in Dhaka, Bangladesh, where previous studies have found low sustained uptake of chlorine water treatment products. The median detection threshold was 0.70 mg/L (n=25, SD=0.57) for water dosed with liquid sodium hypochlorite (NaOCl) and 0.73mg/L (n=25, SD=0.83) for water dosed with solid sodium dichloroisocyanurate (NaDCC). Median acceptability thresholds (based on user report) were 1.16 mg/L (SD=0.70) for NaOCl and 1.26mg/L (SD=0.67) for NaDCC. There was no significant difference in detection or acceptability thresholds for dosing with NaOCl versus NaDCC. Although users are willing to accept treated water in which they can detect the taste of chlorine, their acceptability limit is well below the 2.0mg/L that chlorine water treatment products are often designed to dose. For some settings, reducing dose may increase adoption of chlorinated water while still providing effective disinfection.

V. cholerae can survive in the river systems, Bangladesh

Grant SL, Tamason CC, Hoque BA, Jensen PK. Drinking cholera: salinity levels and palatability of drinking water in coastal Bangladesh. Trop Med Int Health. 2015 Apr;20(4):455-61. doi: 10.1111/tmi.12455. 

OBJECTIVES: To measure the salinity levels of common water sources in coastal Bangladesh and explore perceptions of water palatability among the local population to investigate the plausibility of linking cholera outbreaks in Bangladesh with ingestion of saline-rich cholera-infected river water.

METHODS: Hundred participants took part in a taste-testing experiment of water with varying levels of salinity. Salinity measurements were taken of both drinking and non-drinking water sources. Informal group discussions were conducted to gain an in-depth understanding of water sources and water uses.

RESULTS: Salinity levels of non-drinking water sources suggest that the conditions for Vibrio cholerae survival exist 7-8 days within the local aquatic environment. However, 96% of participants in the taste-testing experiment reported that they would never drink water with salinity levels that would be conducive to V. cholerae survival. Furthermore, salinity levels of participant’s drinking water sources were all well below the levels required for optimal survival of V. cholerae. Respondents explained that they preferred less salty and more aesthetically pleasing drinking water.

CONCLUSION: Theoretically, V. cholerae can survive in the river systems in Bangladesh; however, water sources which have been contaminated with river water are avoided as potential drinking water sources. Furthermore, there are no physical connecting points between the river system and drinking water sources among the study population, indicating that the primary driver for cholera cases in Bangladesh is likely not through the contamination of saline-rich river water into drinking water sources.

Microbial Contamination of Drinking Water Tubewells; Bangladesh

Dey NC, Parvez M, Dey D, Saha R, Ghose L, Barua MK, Islam A, Chowdhury MR. Microbial contamination of drinking water from risky tubewells situated in different hydrological regions of Bangladesh. Int J Hyg Environ Health. 2016 Dec 29. pii: S1438-4639(16)30270-X. doi: 10.1016/j.ijheh.2016.12.007.

This study, conducted in 40 selected upazilas covering four hydrological regions of Bangladesh, aimed at determining the risk of selected shallow tubewells (depth<30m) used for drinking purpose (n=26,229). This was based on WHO’s sanitary inspection guidelines and identifying the association of sanitary inspection indicators and risk scores with microbiological contamination of shallow tubewells. The main objective of the study was to observe the seasonal and regional differences of microbial contamination and finally reaching a conclusion about safe distance between tubewells and latrines by comparing the contamination of two tubewell categories (category-1: distance ≤10m from nearest latrine; n=80 and category 2: distances 11-20m from nearest latrine; n=80) in different geographical contexts. About 62% of sampled tubewells were at medium to high risk according to WHO’s sanitary inspection guidelines, while the situation was worst in south-west region. Microbiological contamination was significantly higher in sampled category-1 tubewells compared to category-2 tubewells, while the number of contaminated tubewells and level of contamination was higher during wet season. About 21% (CI95=12%-30%), 54% (CI95=43%-65%) and 58% (CI95=46%-69%) of water samples collected from category-1 tubewells were contaminated by E. coli, FC, and TC respectively during the wet season. The number of category-1 tubewells having E.coli was highest in the north-west (n=8) and north-central (n=4) region during wet season and dry season respectively, while the level of E.coli contamination in tubewell water (number of CFU/100ml of sample) was significantly higher in north-central region. However, the south-west region had the highest number of FC contaminated category-1 tubewells (n=16 & n=17; respectively during wet and dry season) and significantly a higher level of TC and FC in sampled Category-1 tubewells than north-west, north-central and south-east region, mainly during wet season. Multivariate regression analysis could identified some sanitary inspection indicators, such as tubewell within <10m of latrine, platform absent/broken, pollution source (i.e. household’s waste dumping point/poultry/dairy farm) within 10m of tubewell and unimproved sanitation facility which were significantly associated with presence of microbial contaminants in tubewell water (p<0.01). A tubewell with high risk level was associated with a higher chance of having FC and TC in tubewell water than a tubewell with a medium risk during wet season, but no such conclusion could be drawn in case of E.coli contamination. Construction of pit latrine in areas with high water table should be highly discouraged. Raised sealed pits or flush/pour flash to septic tank could be installed considering sanitary inspection criteria. Water should be treated before drinking.

Child Intelligence and Water Arsenic and Manganese Reduction

Wasserman GA, Liu X, Parvez F, Factor-Litvak P, Kline J, Siddique AB, Shahriar H, Uddin MN, van Geen A, Mey JL, Balac O, Graziano JH. Child Intelligence and Reductions in Water Arsenic and Manganese: A Two-Year Follow-up Study in Bangladesh. Environmental health perspectives. 2015 Dec 29.

BACKGROUND: Arsenic (As) exposure from drinking water is associated with modest intellectual deficits in childhood. It is not known whether reducing exposure is associated with improved intelligence.

OBJECTIVE: To determine whether reducing As exposure is associated with improved child intellectual outcomes.

METHODS: Three hundred and three 10-year-old children drinking from household wells with a wide range of As concentrations were enrolled at baseline. In the subsequent year, deep community wells, low in As, were installed in villages of children whose original wells had high water As (WAs ≥50 µg/L). For 296 children, WISC-IV intelligence, using a version modified for the study population, was assessed at baseline and approximately two years later; analyses considered standardized scores for both Full Scale IQ and Verbal Comprehension, Perceptual Reasoning, Working Memory, Processing Speed Indices. Creatinine-adjusted urinary arsenic (UAs/Cr), blood As (BAs) and blood manganese (BMn) were assessed at both times.

RESULTS: UAs/Cr concentrations declined significantly by follow-up for both the High and Low (< 50 µg/L) WAs subgroups. At baseline, adjusting for maternal age and intelligence, plasma ferritin, head circumference, home environment quality, school grade and BMn, UAs/Cr was significantly negatively associated with Full Scale IQ, and with all Index scores (except Processing Speed). After adjusting for baseline Working Memory scores and school grade, each 100-µg/g reduction in UAs/Cr from baseline to follow-up was associated with a 0.91 point increase in Working Memory (95% CI: 0.14, 1.67). The change in UAs/Cr across follow-up was not significantly associated with changes in Full Scale IQ or Index scores.

CONCLUSIONS: Installation of deep, low As, community wells lowered UAs, BAs and BMn. A greater decrease in UAs/Cr was associated with greater improvements in Working Memory scores, but not with a greater improvement in Full Scale IQ.

Elevated Childhood Arsenic Exposure Despite Reduced Drinking Water Concentrations

Kippler M, Skröder H, Rahman SM, Tofail F, Vahter M. Elevated childhood exposure to arsenic despite reduced drinking water concentrations – A longitudinal cohort study in rural Bangladesh. Environment International. 2015 Nov 12;86:119-125. doi: 10.1016/j.envint.2015.10.017.

OBJECTIVES: The aim of this study was to evaluate the massive efforts to lower water arsenic concentrations in Bangladesh.

METHODS: In our large mother-child cohort in rural Matlab, we measured the arsenic concentrations (and other elements) in drinking water and evaluated the actual exposure (urinary arsenic), from early gestation to 10 years of age (n=1017).

RESULTS: Median drinking water arsenic decreased from 23 (2002-2003) to <2μg/L (2013), and the fraction of wells exceeding the national standard (50μg/L) decreased from 58 to 27%. Still, some children had higher water arsenic at 10years than earlier. Installation of deeper wells (>50m) explained much of the lower water arsenic concentrations, but increased the manganese concentrations. The highest manganese concentrations (~900μg/L) appeared in 50-100m wells. Low arsenic and manganese concentrations (17% of the children) occurred mainly in >100m wells. The decrease in urinary arsenic concentrations over time was less apparent, from 82 to 58μg/L, indicating remaining sources of exposure, probably through food (mean 133μg/kg in rice).

CONCLUSION: Despite decreased water arsenic concentrations in rural Bangladesh, the children still have elevated exposure, largely from food. Considering the known risks of severe health effects in children, additional mitigation strategies are needed.

Arsenic in Bangladesh and West Bengal Groundwater

Mohammad Mahmudur Rahman, Zhaomin Dong, Ravi Naidu. Concentrations of arsenic and other elements in groundwater of Bangladesh and West Bengal, India: Potential cancer risk. Chemosphere. Volume 139, November 2015, Pages 54–64.

We investigated the concentrations of 23 elements in groundwater from arsenic (As) contaminated areas of Bangladesh and West Bengal, India to determine the potential human exposure to metals and metalloids. Elevated concentrations of As was found in all five study areas that exceeded the World Health Organization (WHO) guideline value of 10 μg/L. The mean As concentrations in groundwater of Noakhali, Jalangi and Domkal, Dasdia Nonaghata, Deganga and Baruipur were 297 μg/L, 262 μg/L, 115 μg/L, 161 μg/L and 349 μg/L, respectively. Elevated concentrations of Mn were also detected in all areas with mean concentrations were 139 μg/L, 807 μg/L, 341 μg/L, 579 μg/L and 584 μg/L for Noakhali, Jalangi and Domkal, Dasdia Nonaghata, Deganga and Baruipur, respectively. Daily As intakes from drinking water for adults and the potential cancer risk for all areas was also estimated. Results suggest that mitigation activities such as water treatment should not only be focused on As but must also consider other elements including Mn, B and Ba. The groundwater used for public drinking purposes needs to be tested periodically for As and other elements to ensure the quality of drinking water is within the prescribed national guidelines.