Salinity puts coastal health at risk

Millions of people in coastal Bangladesh are facing a growing health threat as saline drinking water exposes communities to excessive sodium and is linked to a heightened risk of cardiovascular disease, according to preliminary findings from a study conducted between 2023 and 2025.

The evidence highlights an increasingly urgent overlap between water insecurity, climate change and non-communicable diseases, with experts warning that saltwater intrusion is no longer simply an environmental problem but a public health crisis requiring coordinated action.

The findings were presented at a high-level policy and dissemination seminar, “Drinking Water Salinity and Impact on Health: Bangladesh Evidence and Policy Recommendations”, organised by icddr,b in collaboration with Imperial College London at the Sasakawa Auditorium of icddr,b in Mohakhali, Dhaka on Monday.

Dr Aliya Naheed, Senior Scientist at icddr,b, presented preliminary findings from the Bangladesh programme of the NIHR Global Health Research Centre for Non-Communicable Diseases and Environmental Change.

The study first examined drinking-water sources across 172 villages in 71 Community Clinic catchment areas in Koyra Upazila of Khulna, the intervention area, and Assasuni Upazila of Satkhira, the usual-care comparison area.

Researchers surveyed 27,697 water sources, of which 6,703, or 24.2 per cent, were being used for drinking. More than half of the drinking-water sources in Koyra — 55.3 per cent — were saline, compared with 23.3 per cent 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, while women may face additional risks during pregnancy,” Dr Aliya said.

High cardiovascular risk
The research also assessed cardiovascular disease risk among 15,471 adults aged 40 and above in the two upazilas.

Around one in five participants, or 21.6 per cent, were estimated to have a moderate-to-high 10-year risk of cardiovascular disease, defined as a risk of at least 10 per cent.

The estimated risk was 19.7 per cent in Koyra and 23.6 per cent in Assasuni — substantially higher than the national estimate of around 9.02 per cent.

The findings have prompted the research team to develop a package combining water and primary healthcare interventions with digital technology.

The proposed water intervention seeks to improve access to low-salinity drinking water through community awareness and 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 and tube wells. A digital registry and monitoring system for drinking-water sources has also been proposed.

Climate change intensifies threat
Research conducted in coastal Bangladesh over nearly two decades has found associations between saline drinking water, particularly sodium exposure, and elevated blood pressure.

Professor Paolo Vineis of Imperial College London said existing research had not established a clear health-based threshold for salinity in drinking water.

He called for national and international institutions to consider developing an appropriate health-based guideline while further research continues to clarify the health effects of sodium and other minerals in drinking water.

Professor Adrian Butler, also of Imperial College London, presented evidence showing that tropical cyclones and storm surges can cause prolonged salinisation of drinking-water ponds and shallow groundwater.

He stressed the importance of maintaining and, where necessary, raising polder embankments, as well as rapidly cleaning and restoring water sources after storm surges.

Dr Tahmeed Ahmed, Executive Director of icddr,b, said evidence linking climate change to health outcomes in Bangladesh remained limited, with even less research available on practical adaptation measures.

“icddr,b is working to address these critical gaps by generating evidence and testing solutions that connect safe drinking water, primary healthcare and community participation.

Through our collaboration with Imperial College London, we are moving from understanding the problem to evaluating approaches that can protect climate-vulnerable communities,” he said.

Fahmida Khanom, Secretary In-Charge of the Ministry of Environment, Forest and Climate Change, attended the seminar as chief guest.

“Salinity is already a major health problem for coastal communities, and climate change will intensify salinity intrusion,” she said, adding that evidence from Bangladesh could strengthen the country’s position in international climate negotiations and support stronger adaptation and mitigation strategies.

Call for integrated response
Government officials, academics, development agencies, researchers and media representatives joined a panel discussion and open session at the seminar.

Participants called for stronger monitoring and sharing of water-quality data, health-based guidance on sodium levels in drinking water, closer coordination among ministries and sustainable management of water sources.

They also stressed the need to protect communities from climate-related hazards and integrate safe-water measures with prevention of non-communicable diseases and primary healthcare.

The findings underscore the growing challenge faced by coastal communities, where climate-driven salinity intrusion is threatening not only access to safe drinking water but also long-term health.