Salinity in drinking water raises heart disease, stroke risk in coastal Bangladesh: icddr,b

High salinity in drinking water is exposing people in coastal Bangladesh to increased risks of heart disease and stroke, according to findings from a recent study by the icddr,b.

The study found more than half of the drinking-water sources used by residents of Khulna's Koyra upazila are saline, while one in five adults in two coastal upazilas faces a moderate-to-high risk of developing cardiovascular disease.

The preliminary findings were presented today (24 August) at a high-level policy and dissemination seminar titled "Drinking Water Salinity and Impact on Health: Bangladesh Evidence and Policy Recommendations", organised by icddr,b in collaboration with Imperial College London at icddr,b in Dhaka's Mohakhali.

The study was conducted between 2023 and 2025 under the Bangladesh programme of the NIHR Global Health Research Centre for Non-Communicable Diseases and Environmental Change. Researchers surveyed 27,697 water sources across 172 villages in Koyra of Khulna and Assasuni of Satkhira. Of these, 6,703 were used as drinking-water sources.

The survey found that 55.3% of drinking-water sources in Koyra were saline, compared with 23.3% in Assasuni.

"For millions of people living in coastal Bangladesh, the water they depend on every day is becoming a growing health concern. Drinking-water salinity is no longer only an environmental challenge; increasing sodium exposure can contribute to high blood pressure and related cardiovascular and kidney diseases," Dr Aliya Naheed, senior scientist at icddr,b, said.

The research also assessed the cardiovascular health of 15,471 adults aged 40 and above. It found that nearly one in five (21.6%) had a moderate-to-high risk of developing cardiovascular disease — heart disease or stroke — within a decade. The prevalence was 19.7% in Koyra and 23.6% in Assasuni.

Based on the findings, the research team has developed a package of water and primary healthcare interventions incorporating digital innovation. The water component aims to improve access to safe drinking water through community engagement, better operation and maintenance of water sources, and stronger local governance and monitoring.

The package includes communal and household rainwater harvesting systems, pond sand filters, tube wells, and a proposed digital registry and monitoring system.

Professor Paolo Vineis of Imperial College London said existing scientific evidence had yet to establish a clear health-based threshold for salinity in drinking water.

Meanwhile, Professor Adrian Butler of Imperial College London warned that cyclone-induced storm surges can contaminate ponds and shallow groundwater for prolonged periods, underscoring the importance of restoring water sources after disasters.

Dr Tahmeed Ahmed, executive director of icddr,b, said Bangladesh still had limited evidence linking climate change to health outcomes and even fewer studies evaluating practical adaptation strategies.

"Through our collaboration with Imperial College London, we are moving from understanding the problem to testing solutions that connect safe drinking water, primary healthcare and community participation," he said.

Fahmida Khanom, secretary in charge of the climate change ministry, said the evidence would strengthen both national policy and Bangladesh's position in international climate negotiations on adaptation.

Professor Dr Pravath Chandra Biswas, director general of the Directorate General of Health Services, chaired the seminar.

"We now have years of evidence on salinity and health. The task is to bring that evidence together and translate it into practical guidance and policy, while strengthening prevention and management of non-communicable diseases through primary healthcare," he said.