Focus/Spotlight

Eating fish in Sri Lanka – The unseen risk

By Sarah hannan

According to statistics from the Royal Statistical Society (RSS), in 2018, only 9.5% of plastics were recycled globally and the balance 90% comprised single-use plastics such as lunch sheets, carbon pens, and plastic straws. These single-use plastics later contributed towards the generation of microplastics that are polluting the environment.

Sri Lanka is not shielded from this issue, and in our previous article headlined “Increase in microplastics in seas: A growing concern for Sri Lanka” published on 1 March, we mentioned that the majority of Sri Lanka’s microplastics are generated by abandoned fishing gear and litter left behind by fishermen.

We then contacted Department of Fisheries and Aquatic Resources Director General G.P. Janaka Kumara to ask what steps the Department has taken to minimise the amount of plastic debris added to the ocean daily.

“As of January, with the involvement of the Ministry of Fisheries and Aquatic Resources, the Marine Environment Protection Authority, the Department of Coast Conservation and Coastal Resource Management, and the Sri Lanka Navy have conducted clean-up initiatives not only on the beach, but also within the shallow sea area up to 10 km from the shoreline. The initiative was headed by our State Minister (of Fisheries and Freshwater Fishing Industry) Sanath Nishantha Perera and involved about 50 divers who assisted in cleaning up the coral reef off the Puttalam shore,” Kumara responded.

Any piece of plastic or fibre particle below the size of 5 mm is considered a microplastic. For example, the small beads in your toothpaste or your face wash are considered as primary microplastics. While secondary microplastics are generated when plastic products start to disintegrate in the environment, breaking them into smaller particles, the formation of microplastics in the ocean is influenced by a combination of environmental factors and the properties of the polymer the final product is made of.

During the clean-up, the team had also collected a lot of plastic waste on the seabed and had cut loose fishing nets entangled in the coral reef. Meanwhile, the Ministry of Fisheries and Aquatic Resources had also created awareness among the fishermen to carry large water bottles instead of small water bottles and further informed them to not litter at sea.

Kumara also stated that the Ministry is closely working with the local government bodies of these coastal fishing villages to keep the beaches clean as well as to dispose garbage in a responsible manner.

When asked whether the Department had noticed a reduction in fish stocks in the northwestern seas, which is reported to have the most amounts of microplastics, Kumara stated that at present, there have been no reports of fish stock depletion. However, as studies reveal, the Department believes there might be a long-term effect on aquatics resources and therefore it is important to keep our beaches and seas clean.

University of Sri Jayewardenepura (USJ) Faculty of Medical Sciences Department of Anatomy lecturer and clinical geneticist Dr. Sajith Edirisinghe, elaborating on the impact Sri Lanka’s microplastics could have on humans, stated: “These microplastics, through the waterways, end up in the ocean and as you know, there are marine resources in the ocean that are well visible as well as not so visible to the eye. Microplastics are ingested by the primary sources of the food chain, such as plankton, which cannot differentiate whether it is a piece of plastic or food. The plankton is then consumed by bigger fish and humans end up consuming this fish.”

Therefore, humans too ingest microplastics when they consume foods such as shrimp, prawns, crabs, shark, tuna, etc. as these marine resources would have consumed microplastics through their food chain. Dr. Edirisinghe, citing a study conducted by the University of Newcastle in Australia, informed The Sunday Morning that on average, people would consume about 5 g of plastic per week through various food sources and drinking water.

“Microplastics absorb various chemical ingredients and chemical byproducts in the ocean and can create a cocktail of contaminants. These chemicals can easily cause cancers if ingested. For instance, bisphenol A (BPA) can cause breast cancer; lead (Pb) can cause cancers in the lungs, brain, and pancreas; polycyclic aromatic hydrocarbons (PAHs) can cause cancers in the bladder, liver, skin, and digestive tract; and polychlorinated biphenyls (PCBs) can cause cancers in the liver and gallbladder,” Dr. Edirisinghe explained.

He further noted that these are only a few of the recognised chemicals considered cancerous. Also, he noted that microplastics could easily affect the endocrine system after ingested, releasing all these chemicals that were absorbed from the outside environment, eventually leading to the development of colon, prostate, and ovarian cancers.

Effects of microplastics
  1. Microplastics are ingested by a wide range of marine organisms including invertebrates, fish, and birds, and in some organisms, the incidence of ingestion is widespread across populations.
  2. The movement, storage, and elimination of microplastics by marine organisms will depend on the size of the particle. Particles at the smaller end of the size spectrum (nanoscales) have been shown to cross membranes into cells in controlled laboratory experiments.
  3. When microplastics cross cell membranes, some tissues have been shown, in vitro, to exhibit a response to the presence of particles, i.e. causing inflammation and cell damage, followed by healing responses and fibrous encapsulation of particles.
  4. The risk of associated effects following exposure to microplastics will depend on the number of particles; the size distribution, shape, surface properties, polymer composition, and density of the particles; the duration of exposure; the kinetics of absorption and desorption of contaminants with respect to the plastic and the organism; and the biology of the organism.
  5. Marine organisms are exposed to microplastics via the same pathways used for food including filtration, active grazing, deposit feeding, and via transport across the gills.
  6. Microplastics may be transferred from prey to predator, but the process will be species-specific.
  7. Among the various types of seafood, the consumption of filter feeding invertebrates, such as mussels or oysters, appears the most likely route of human exposure to microplastics. However, there is no evidence to confirm this is occurring.
  8. The ingestion of microplastics may have an effect on the feeding, movement, growth, and breeding success of the host organism.
Source: GESAMP reports and studies, No. 90, Microplastics in the Ocean