Stepped-wedge cluster-randomised controlled trial to assess the cardiovascular health effects of a managed aquifer recharge initiative to reduce drinking water salinity in southwest coastal Bangladesh: study design and rationale

Abstract

IntroductionSaltwater intrusion and salinisation have contributed to drinking water scarcity in many coastal regions globally, leading to dependence on alternative sources for water supply. In southwest coastal Bangladesh, communities have few options but to drink brackish groundwater which has been associated with high blood pressure among the adult population, and pre-eclampsia and gestational hypertension among pregnant women. Managed aquifer recharge (MAR), the purposeful recharge of surface water or rainwater to aquifers to bring hydrological equilibrium, is a potential solution for salinity problem in southwest coastal Bangladesh by creating a freshwater lens within the brackish aquifer. Our study aims to evaluate whether consumption of MAR water improves human health, particularly by reducing blood pressure among communities in coastal Bangladesh.Methods and analysisThe study employs a stepped-wedge cluster-randomised controlled community trial design in 16 communities over five monthly visits. During each visit, we will collect data on participants’ source of drinking and cooking water and measure the salinity level and electrical conductivity of household stored water. At each visit, we will also measure the blood pressure of participants ≥20 years of age and pregnant women and collect urine samples for urinary sodium and protein measurements. We will use generalised linear mixed models to determine the association of access to MAR water on blood pressure of the participants.Ethics and disseminationThe study protocol has been reviewed and approved by the Institutional Review Boards of the International Centre for Diarrheal Disease Research, Bangladesh (icddr,b). Informed written consent will be taken from all the participants. This study is funded by Wellcome Trust, UK. The study findings will be disseminated to the government partners, at research conferences and in peer-reviewed journals.Trial registration numberNCT02746003; Pre-results.

Urinary Sodium Excretion and Blood Pressure Relationship across Methods of Evaluating the Completeness of 24-h Urine Collections

“…The first cohort study followed up 383 participants for two visits (742 person-visits) from southwest coastal Bangladesh during the wet season [ 21 ]. The second study was a population-based stepped-wedge randomized controlled trial in southwest coastal Bangladesh that followed up 1190 participants for five monthly visits (5745 person-visits) during the dry season [ 22 , 23 ]. The third cohort study followed up 293 participants from southwest coastal and 277 from non-coastal central Bangladesh for seven visits covering both wet and dry seasons (3547 person-visits data: 1773 from coastal and 1774 from non-coastal regions) [ 24 ].…”

Impacts of Salinity Intrusion in Community Health: A Review of Effectiveness of Adaptation Measures to Decrease Drinking Water Sodium (DWS) from Coastal Areas of Bangladesh

“…Furthermore, in the midst of the dry season, ponds repeatedly dried up leaving coastal population with few or no options but to extricate saline groundwater utilizing hand pumps for drinking and cooking, whereas amidst the monsoon (May to October), coastal population generally gather rainwater through household-or-community-level rainwater harvesting schemes [31]. It is, therefore, clear, that saltwater invasion as well as salinisation partakes consumable water shortages regionally and globally around the coasts, forcing the people to be dependent on the substitute sources for water consumption [29]. Coastal communities in Bangladesh, however, had little consciousness of the dangers related with superfluous salt consumption in their food.…”

“…While these interventions may be effective in reducing DWS exposure [31], MAR is a promising adaptive approach for increasing the accessibility of salt free potable water that sustains almost a yearly water supply. Since MAR storage of rainwater occur under confined conditions, it is further secured from evaporation as well as strong to tidal storms, cyclones and saltwater permeation (Figure 4) [29,35]. In MAR, a freshwater lens is purposefully created amidst the brackish aquifers, to supply with the surface freshwater or rainwater to the aquifers to bring the hydrological equilibrium.…”

“…In MAR, a freshwater lens is purposefully created amidst the brackish aquifers, to supply with the surface freshwater or rainwater to the aquifers to bring the hydrological equilibrium. It is a likely to be a key solution for salinity problem in the southwest coastal Bangladesh [29].…”

Community finance and promotion of Managed Aquifer Recharge systems affect uptake and sustainability as a potable water source in southwest coastal Bangladesh: A qualitative study

“…The Geology Department of the University of Dhaka, in collaboration with Unicef piloted 18 MAR projects, in three districts of south-west Bangladesh; Khulna, Shatkhira and Bagerhat [6].The MAR pilot study demonstrated the potential for increasing freshwater availability and sustainable year-round drinking water supplies. Subsequently 80 MAR systems have been installed in these regions and a health impact evaluation of MAR water access on blood pressure and kidney function has recently concluded [1,6,19,20].…”