Bangladesh’s coasts face higher microplastic threat than China

A recent doctoral study has revealed that coastal and estuarine environments in Bangladesh are more heavily polluted with microplastics (MPs) than those in China, posing serious threats to marine biodiversity, human health, and the effectiveness of pollution control mechanisms.

The research, conducted by Dr Mazharul Islam, an instructor at the Bangladesh Marine Fisheries Academy, under the supervision of Professor Minggang Cai at Xiamen University, presents a comparative analysis of microplastic contamination in the northern Bay of Bengal and China's Xiamen Bay.

This is the first comprehensive study of its kind to examine microplastics in water, sediments, and fish tissue across two major Asian coastal regions. Using cutting-edge spectroscopic tools and ecological risk assessments, the study calls for urgent policy action—especially in Bangladesh—to address the escalating marine pollution crisis.

Pollution levels are higher in Bangladesh coastal waters

The southeastern estuarine and coastal waters of Bangladesh exhibit significantly higher concentrations of microplastics compared to those in the waters of China. In the Bangladeshi study areas, surface waters contained an average of 560 ± 401 MPs items per cubic meter, while sediments held 130.4 ± 62.9 items per kilogram. These figures were nearly double those found in China's Jiulong Estuary and Xiamen Bay, where surface water contained 328±63.2 items/m³ and sediment samples had 68.3±36.0 items/kg.

In both countries, fibres emerged as the dominant microplastic shape, making up 60% of waterborne MPs and 56% of those in sediment in Bangladesh. Other forms included fragments and lines. Polypropylene (PP) and acrylic were the most prevalent polymer types in water and sediment, respectively, with black being the most commonly observed colour. Most particles measured between 200 and 500 micrometres in size, posing a high risk of ingestion by aquatic organisms.

Bangladesh's fish show higher ingestion of MPs

The disparity between the two countries becomes even more concerning when examining the ingestion of microplastics in fish. Fish from Bangladeshi waters ingested an average of 32.9±31.0 MPs items per 10 grams of tissue—more than twice the average found in China, where the figure was 13.4±4.6 items/ind.10g⁻¹. In some Bangladeshi fish samples, the microplastic count reached close to 100 items per sample.

Fibers were again the most commonly ingested form, accounting for 93.1% of microplastics in Bangladeshi fish and 85.2% in Chinese samples. The most frequently detected polymers in fish tissue were polyvinyl alcohol (PVA), polyethersulfone (PES), polyethene (PE), and acrylic. Black particles were predominant in both countries.

The study found a notable inverse relationship between the physical size of fish—measured by length, girth, and body weight—and the concentration of microplastics in their tissues. This suggests that smaller fish or those closer to the seabed, such as demersal species, are at greater risk of contamination.

Health and ecological risks identified

To assess environmental and public health risks, the study employed three key indices: the Potential Ecological Risk Index (PERI), the Contamination Factor (CF), and the Pollution Load Index (PLI). Results from Bangladesh indicated medium to very high ecological risks in estuarine and coastal zones, largely due to untreated wastewater discharge. The Estimated Daily Intake (EDI) values for adults and children consuming locally raised fish raised concerns about possible long-term health effects.

In contrast, the corresponding ecological risk levels in China were lower, ranging from low to moderate. This difference was attributed to China's relatively stronger regulatory enforcement and improved waste treatment infrastructure.

Policy gaps between the two nations

One of the study's major contributions is its critical analysis of national policy responses to marine plastic pollution. China has taken a proactive stance, rolling out a series of robust measures including the National Sword Policy, the Plastic Pollution Control Action Plan, and the Marine Environmental Protection Law. These national efforts are further reinforced through international cooperation with entities such as the United Nations Environment Programme (UNEP) and the Basel Convention.

Bangladesh, although committed on paper through legal instruments such as the Environment Conservation Act and the Marine Fisheries Act, continues to face significant implementation challenges. Weak enforcement, inadequate institutional capacity, and limited public engagement hinder the effectiveness of these laws. In many cases, local pollution control depends more on community recognition and volunteer efforts than on systemic regulatory action.

Recommendations for Bangladesh

The study concludes with an urgent call to action for Bangladesh to overhaul its marine pollution management strategies. Strengthening the enforcement of existing environmental laws is a starting point. A national action plan targeting the reduction of single-use plastics is also crucial.

Bangladesh needs to invest in wastewater treatment infrastructure, particularly in urban and industrial zones near the coast. Adoption of biodegradable materials, expansion of recycling facilities, and integration of nanofiltration systems are recommended as technological solutions. The researcher also emphasizes the importance of public-private partnerships and regional cooperation in mitigating the pollution crisis. Raising awareness through community-level education campaigns could further empower local stewardship.

Hope through innovation and collaboration

Despite the sobering evidence, the study offers a note of optimism. It highlights emerging innovations such as biodegradable polymers, advanced waste filtration systems, and efficient plastic segregation technologies that hold promise in reducing marine microplastic pollution. Furthermore, the study advocates for stronger transboundary cooperation between nations sharing coastal vulnerabilities.

Bangladesh and China, though facing different levels of the crisis, can learn from each other. While China's governance model offers examples of regulatory effectiveness, Bangladesh can contribute valuable insights from its community-based environmental initiatives.

Md Mazharul Islam concludes that "protecting coastal ecosystems from the silent threat of microplastics demands urgent, coordinated, and innovative efforts—from policymakers, industries, and citizens alike." His research contributes to the growing body of global evidence that microplastics pose not only an environmental hazard but also a public health and governance crisis. With strategic attention and action, Bangladesh still has the opportunity to reverse the tide.