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.

INTRODUCTION: Saltwater 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 ANALYSIS: The 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 DISSEMINATION: The 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 NUMBER: NCT02746003; Pre-results

Dietary intake of heavy metals from eight highly consumed species of cultured fish and possible human health risk implications in Bangladesh

Concentrations of five heavy metals (Pb, Cd, Cr, As and Hg) in eight highly consumed cultured fish species (Labeo rohita, Clarias gariepinus, Hypophthalmichthys molitrix, Cyprinus capio, Puntius sarana, Oreochromis mossambicus, Pangasius pangasius and Anabas testudineus) collected from four wholesale markets of Dhaka city, Bangladesh (Karwan Bazar, Mohammadpur Town Hall, Newmarket and Mirpur-1) were measured using atomic absorption spectrometry (AAS) in order to evaluate the potential human health risks from the consumption of fish. The estimated daily intake (EDI) of all the studied heavy metals calculated on the basis of mean fish consumption of 49.5 g personâ1 dâ1 by Bangladeshi households indicated that no risk to peopleâs health with respect to the EDI of investigated heavy metals through the consumption of the fish samples. From the human health point of view, the estimation of non-carcinogenic risk indicated that intake of individual heavy metal through the consumption of fish was safe for human health, whereas, consumption of combined heavy metals suggested potential health risk to highly exposed consumers. However, the estimation of carcinogenic risk of arsenic due to the consumption of fish indicated that consumers remain at risk of cancer. Keywords: Heavy metals, Fish, Estimated daily intake, Carcinogenic and non-carcinogenic risk, Human health risk

Development and validation of a GF-AAS method and its application for the trace level determination of Pb, Cd, and Cr in fish feed samples commonly used in the hatcheries of Bangladesh

Abstract Background A sensitive, accurate and precise method was developed and validated in regard to Council Directive 333/2007/EC, Commission Decision 657/2002/EC, ISO/IEC 17025:2005 and EURACHEM 1998 for the trace level determination of Lead (Pb), Cadmium (Cd) and Chromium (Cr) in fish feed samples using Graphite Furnace Atomic Absorption Spectrometry (GF-AAS). Methods For method validation, selectivity, working and linear ranges, limit of detection (LoD), limit of quantification (LoQ), trueness (recovery) and precision (repeatability and reproducibility) have been assessed as performance criteria. Results The method LoDs for Pb, Cd and Cr were found to be 0.078, 0.010 and 0.022 μg/g respectively, whereas, the method LoQs were obtained at 0.156, 0.021 and 0.044 μg/g respectively. Moreover, the recovery of the analytes was 90 – 104% and the RSD values for precision were 4.90 – 9.60% respectively. Conclusions The method validation performance criteria indicate the method’s suitability for trace level quantification of Pb, Cd, and Cr in fish feed samples