Dhaka's lakes turning into microplastic reservoirs, study warns
The study also found deteriorating water quality, particularly in Gulshan Lake, where dissolved oxygen levels had dropped below the standard required for aquatic life.
Highlights:
- Severe levels of microplastics found in Dhanmondi, Gulshan, Hatirjheel lakes: Study
- Record concentration of microplastics is in Gulshan Lake
- Such elements contaminate water, sediment, fish
- Experts warn residents against eating fish from polluted lakes
- Nearly 8,000 billion microbeads released into Dhaka's environment every month
Dhaka's major lakes – Dhanmondi, Gulshan and Hatirjheel – considered as the capital's recreational spaces and environmental "lungs," are now heavily contaminated with microplastics, raising fresh concerns about ecological damage and food safety.
A recent study published in the international journal "Heliyon" found alarming concentrations of microplastics in lake water, sediment and fish, warning that the pollution is already entering the aquatic food chain and potentially threatening human health.
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The study, titled "Abundance and characteristics of microplastics in major urban lakes of Dhaka, Bangladesh," was conducted by researcher Fariha Tahsin Mercy along with Professor AKM Rashidul Alam and Md Ahedul Akbor.
Using advanced chemical analysis known as Fourier-transform infrared spectroscopy (FTIR), researchers identified several common plastic polymers in the lakes. High-density polyethene (HDPE) – widely used in detergent bottles and milk containers – was the most dominant type, followed by PVC, polycarbonate and polypropylene.
Among the three lakes, Gulshan Lake was identified as the most polluted. Researchers recorded the highest concentration of microplastics in both surface water and sediment. There were 36 plastic particles per litre of water and 67 particles per kilogram of sediment.
The study also found deteriorating water quality, particularly in Gulshan Lake, where dissolved oxygen levels had dropped below the standard required for aquatic life.
Gulshan and Hatirjheel lakes act as sinks for microplastics because they receive massive volumes of urban runoff and lack sufficient water outflow, said the researchers.
Dhanmondi Lake, located in a largely residential area with fewer sewer outlets, showed comparatively lower levels of microplastics in water and sediment. However, researchers found the most concerning results in fish collected from the lake.
The study examined 90 fish samples from seven species, including tilapia, catla and shol. More than 93% of the fish samples contained microplastics.
One Mozambique tilapia collected from Dhanmondi Lake contained 17 separate plastic particles. On average, fish from the lake carried 8.2 microplastic items per individual fish – the highest among the three lakes.
According to estimates cited in the study, nearly 8,000 billion microbeads are released into Dhaka's environment every month.
The study attributed the contamination to intense human activity, industrial discharge and untreated domestic sewage flowing into the lake.
Researchers warned that the contamination of fish is particularly alarming because microplastics can move through the food chain and eventually enter the human body through consumption.
They also warned that as microplastics accumulate in water bodies and aquatic species, they may carry harmful chemicals and pathogens, potentially causing long-term health effects such as inflammation and cellular damage in humans.
When contacted, water resources expert Ainun Nishat described the situation as a growing environmental disaster.
"People should avoid consuming fish from Dhaka's polluted lakes and rivers. If someone offers you fish from Dhanmondi Lake, Gulshan Lake, or even the Buriganga for free, please don't eat it," he told The Business Standard.
"These water bodies are extremely polluted and toxic," he said.
He said microplastic contamination in Bangladesh has already reached a critical level and stressed the need for greater public awareness.
"The severity of microplastic pollution is real, and it has already reached the stage of a major environmental disaster," Nishat said.
Referring to widespread plastic waste, he added, "Polythene is floating all around us. If you could dive beneath the water surface, you would see layers upon layers of polythene settled at the bottom. Microplastics have already spread as far as the coastal areas."
Environmentalists say the findings reflect Bangladesh's broader struggle with plastic waste management. Despite becoming the first country to ban polythene bags in 2002, enforcement and waste control remain weak.
