The researchers are from Chittagong University and Shahjalal University of Science and Technology
A group of researchers have found the presence of microplastics in five commercially important species of marine fish, raising concerns over public health.
The fish species in question are pink Bombay-duck (locally known as loitta), white Bombay-duck, goldstripe sardinella, brown shrimp and tiger shrimp.
The researchers are from Chittagong University and Shahjalal University of Science and Technology.
The entrails of Bombay-duck are normally not removed during cooking, so the microplastic remains in the fish and enters the human body when consumed. Similarly, the microplastic in shrimp shells also enters the human body when consumed.
Plastic debris less than five millimetres in length are called microplastics. Microplastics damage aquatic creatures, as well as turtles and birds, by blocking digestive tracts, diminishing the urge to eat and altering feeding behaviour, all of which reduces growth and reproductive output. Some species starve and die due to consumption of microplastic.
The study on Bombay-duck and sardinella has been published in “Science of the Total Environment,” while the research paper on penaeid shrimp has been published in “Chemosphere.”
A total of 25 specimens of each species (pink Bombay-duck, white Bombay-duck and gold-stripe sardine) were collected from the Northern Bay of Bengal for examination at the laboratory of the Institute of Marine Sciences at Chittagong University.
During examination, 443 microplastic items were found in the intestines of pink Bombay-duck, white Bombay-duck and goldstripe sardinella. The microplastics were composed of polyamide and polyethylene terephthalate polymers.
The gastrointestinal tracts of 50 tiger shrimps and 100 brown shrimps were examined and a total of 33 and 39 MP items were found in tiger shrimp and brown shrimp, respectively.
The microplastics were composed of polyamide-6 and rayon polymers.
Prof Dr M Shahadat Hossain of the Institute of Marine Sciences at Chittagong University and a member of the research group, told Dhaka Tribune the study findings had raised concerns that microplastics in marine fish could be a threat to public health via the food chain.
“Bombay-duck and sardinella are important fish species in Bangladesh that support employment, economy, food and nutrition for millions of people. The total annual landing of Bombay-duck and sardinella was 58,545 tons and 44,386 tons, respectively, in 2015–16. Bombay-duck is typically dried without processing, so there is no chance of removing the digestive tract when consumed. As a result, microplastics may be transferred to humans,” added Prof Shahadat.
According to the research, about 150 million tons of plastics have already been deposited in the ocean at a rate of 8 million tons per year, amounting to around 15 tons of plastics every minute.
The research findings also show that marine organisms are in continuous interaction with microplastics in the environment and ingestion of microplastics has been reported in cetaceans, seabirds, bivalves, crustaceans, echinoderms, lugworms, zooplankton, sea cucumbers and corals.
Prof Dr Selim Md Jahangir, dean of the Faculty of Medicine at Chittagong University, told Dhaka Tribune that microplastics could cause damage to organs such as the liver and kidney in the short term.
“As a long-term impact, microplastics can cause cancer in the human body,” said Prof Dr Jahangir, who is a former principal of Chittagong Medical College.