Freshwater Salinization and Its Contribution to Urinary Electrolyte Excretion in Coastal Bangladesh

Abstract To evaluate the role of drinking water salinity in electrolyte excretion, we analyzed household-stored drinking water and 24-hour urine samples collected during 9,748 person-visits across three cohort studies in southwest coastal Bangladesh. We fit three-level hierarchical linear mixed-effects models, incorporating natural cubic splines and adjustment for visit number, age, gender, body mass index, physical exercise, smoking status, alcohol consumption, wealth status, religion, and sleep duration. Proportion plots were used to illustrate the model-estimated proportion of total daily urinary electrolyte excretion associated with drinking water salinity. Across varying salinity levels, model-estimated contributions of drinking water salinity to mean 24-hour electrolyte excretion were moderate for sodium (0.4–12.3%), chloride (0.8–12.3%), and potassium (1.4–10.1%), but were more substantial for calcium (4.0–31.8%) and magnesium (2.0–25.0%). These findings highlight the need to consider potential changes in mineral intake and related health outcomes when developing sustainable drinking water management programs that improve water quality while reducing the health impacts of freshwater salinization.