Microplastics in frogs and fish: A grave concern for human health and ecosystems

Plastic waste and pollution in water bodies is a global phenomenon, and from that, it is essentially microplastics that continue to produce dangerous repercussions. 

One of the latest ways is this: Microplastics have been found inside frogs collected from different water bodies of Jahangirnagar University, reveals a new study. This is detrimental to the environment since frogs play a vital role in the food web and help in keeping aquatic ecosystems healthy. 

According to Fahmida Parvin, one of the researchers who found the trace of microplastics in frogs, "The new finding indicates that the reach of microplastics is so deep and severe that it has even reached frogs, which is a relatively lower level consumer in an ecosystem. It indicates that it affects other organisms, which depend on frogs, on the upper level of the food web.

"Microplastics are not only found in Dhaka, we also found them in different districts, and we observed that it goes into the human body through fish consumption," explained Parvin, who is an associate professor of the Department of Environmental Sciences at Jahangirnagar University.

According to reports from various news outlets, including The Guardian, microplastics were found in human breast milk — in 75% of  milk samples collected from 34 healthy mothers — for the first time last year.

Prior to that, the presence of microplastic pollution in human blood was observed, with particles being found in 80% of the individuals tested. 

Sources of microplastics 

The researchers talk about two kinds of sources for plastic in the wetland: primary and secondary microplastics. Primary plastic particles occur in sizes smaller than 5 mm before entering the environment. These originate predominantly from industrial preproduction pellets, which are generally utilised as components of beauty care products, facial cleaners, cosmetics, toothpaste, hand cleaners, exfoliation scrubs, drilling fluids, and clothing. 

Secondary microplastics are derived from the breakdown of large plastic debris (e.g, plastic bottles, plastic bags, face masks, fishing nets, and one-time cups or plates) by wave action, UV radiation, and other physical, chemical and biological processes in the natural environment. 

These plastic particles undergo physical and chemical changes and are converted to microplastics. The microplastics are ultimately ingested by frogs and other wetland animals.  

There was a time when we took reusable bags to grocery shops. Now, bags are available at the vegetable market as well as super shops. Many countries have adopted the 'polluters pay principle,' where bags are offered to shoppers only if they need them, and that too in exchange for a certain amount of toll. That is how, by including the people, regulations can be implemented."

Sharif Jamil, General Secretary, Bangladesh Poribesh Andolon

How this is harming our ecosystem

As per the Environment and Social Development Organisation (ESDO), every year, about 87,000 tonnes of single-use plastic are thrown away in Bangladesh. And this is increasing microplastics in the wetlands, which eventually travel through the rivers and pour out into the Bay of Bengal. 

"Most of our plastic wastes are uncollected and unattended which directly go to the water bodies; and even the collected portion, which are dumped in selected open areas, eventually finds water bodies," SM Mehedi Ahsan, an urban development specialist with special focus on climate change resilience, told The Business Standard. 

These fragmented plastics or microplastics end up in the gastrointestinal systems of wetland creatures like fish, frogs, and even snakes.

In their study 'Identifying the Presence of Microplastics in Frogs from the Largest Delta of the World', published in the journal Environmental Advances, Parvin and her co-researchers  collected 27 frogs from nine species (three frogs from each species) from five different water bodies of the Jahangirnagar University. And  the study found as much as 90% of the frogs had microplastic in their bodies.

In another 2022 study titled, 'Abundance and Characteristics of Microplastics in Major Urban Wetlands of Dhaka, Bangladesh', researchers evaluated the abundance and characteristics of microplastics in water, sediment, and fish samples of three major urban lakes, namely Dhanmondi Lake, Gulshan Lake and Hatirjheel Lake in Dhaka.

And they found an abundance of microplastic that varied from 0-9 items/L in surface water, 0-16 items/kg in sediment, and 0-17 items/individual; 0-4.88 items/g in the gastrointestinal tracts of test fish species. 

In 2023, a team of researchers studied the freshwater fish of the Old Brahmaputra River in north-central Bangladesh. Microplastics were detected in 58.93% of fish, with the highest level in freshwater eels, Mastacembelus armatus (almost 11%). Fibres (49.03%) and pellets (28.02%) were the most frequently found microplastics. Nearly 72% of the microplastic was smaller than 1 mm. 

In a 2021 study published in the journal Environment International showed that microplastic addition decreased the richness and diversity of bacteria. 

Microplastics can change the germination strategies of seeds, and there was also a reduction in fresh weight and plant height. Chlorophyll b synthesis was significantly reduced in mixed microplastic treatments compared with controls. 

The contaminant also had a negative effect on soil enzyme activity. For example, Polystyrene Micro Plastic particles significantly decreased sucrase activity in the soil after 40 days. 

This contamination by microplastic is a global issue now as it greatly deteriorates the ecosystem and negatively impacts the health of various aquatic organisms, such as zooplanktons, bivalves, fish, and amphibians. 

In the research on the Bengal Delta frogs too, the researchers found that the toxic chemicals bioaccumulate in the bodies of frogs and cause severe damage — even mortality. 

Shafi M Tareq, one of the co-authors of the microplastic in frogs study said, "Frog is an important bio indicator, it controls different insects. If we lose frogs due to plastic pollution, this will affect the frogs controlling insects that cause various diseases in humans, like malaria and dengue."

Annual plastic consumption in Bangladesh

Recently, Break Free From Plastic (BFFP), a borderless global organisation published its Global Brand Audit Report, where they found that in Bangladesh, plastic pollution is dominated mainly by Coca Cola, Pran-RFL Group, PepsiCo, Partex Group, Akij Food and Beverage Limited, and Unilever.

The report says that in the last 15 years, Bangladesh's annual per capita plastic consumption in urban areas has tripled. Bangladesh is one of the top plastic-polluting countries due to the mismanagement of plastic waste. 

About 646 tonnes of plastic waste is collected daily in Dhaka, which is 10% of all waste generated in Bangladesh. And only 37.2% of the plastic waste in Dhaka is recycled. 

What can be done?

Sharif Jamil, general secretary of the Bangladesh Poribesh Andolon (BAPA), pointed to Article 6a of the Environment Protection Act 2002, which makes production, marketing or use of any kind of single-use plastic bags and polythene that is harmful to the environment a punishable act. The act seems to have no impact as the common people are yet to realise the danger from the material.

Even in 2020, the High Court directed the government to ban single-use plastic products in the coastal areas and hotels, motels and restaurants across the country.

"Big corporations have no accountability to the government. They are violating the legal framework without any fear of punishment. More than the corporations, it is the government of Bangladesh that needs to be serious about its responsibilities," he said.

"There was a time when we took reusable bags to grocery shops. Now, bags are available at the vegetable market as well as super shops. Many countries have adopted the 'polluters pay principle' where bags are offered to shoppers only if they need them, and that too in exchange for a certain amount of toll. That is how, by including the people, regulations can be implemented," he added. 

SM Mehedi Ahsan said that it would be best if we could get rid of plastic use. Since that is not possible overnight, we can think of reducing the use of plastic to as low as possible. 

Reiterating the same, Parvin suggested that "We can opt for recycled plastic rather than the single used ones. Because keeping plastic in the landfill or burning them is not a solution. Single-use plastics cannot be recycled and ultimately end up in drains and other water bodies." 

She recommends that policy makers and the waste management authorities take it seriously. 

To prevent the loss of frogs and consequent damage to the ecosystem, Shafi M Tareq suggested, "The government can use laws and regulations and educate communities about the danger of plastic use. I would not say we need to leave out plastic altogether, but better management should be in place."

What officials say

When asked about if they have any plan to reduce the microplastics in the city lakes, SM Sharif-ul Islam, chief waste management officer of Dhaka North, said, "We don't have any plan for that."

Dr. Abdul Hamid, Director General, Department of Environment said "We are concerned about it and working on it". However, he refused to give any further details and advised us to talk to the Director of Waste and Chemicals Management, Razinara Begum. Razinara could not be reached over phone as she was out of the country.