Smaller plastic particles are especially dangerous, because they are easily ingested and can enter organs and body fluids of organisms and thus propagate up the food chain. The fact that these particles are also co-contaminated with various chemicals and other pollutants makes accurate assessments of the effects and toxicity of plastic pollution challenging. A group of scientists led by the IAEA has recently published a comprehensive review on the effects on fish of ‘virgin’ micro- and nano-plastics – tiny plastic particles such as resin pellets used in plastics manufacturing. The review, published in the journal Environmental Science and Technology in March 2020, revealed that in 32% of all studies assessed, such virgin plastic particles were indeed affecting biological functions in fish, such as their behavior and neurological functions, as well as their metabolism, intestinal permeability and intestinal microbiome diversity.
Plastic particles below 5 mm in length are called microplastics. The smaller ones, with a size equal to or less than 100 nm (1/10 000 mm) are called nanoplastics. They are so tiny that one cannot see them with naked eye or even with an ordinary optical microscope.
According to the UN Environment Programme, 8 million tonnes of plastic end up the world’s oceans every year, often carried there by rivers. If the trend continues, by 2050 our oceans could contain more plastic than fish Microplastic particles are accidentally consumed by marine organisms, which are then consumed by predator fish. Nanoplastic particles are even more toxic to living organisms as they are more likely to be absorbed through the walls of digestive tracts and thereby transported into the tissues and organs. Consequently, such plastic particles can interfere with various physiological processes, from neurotransmission to oxidative stress and immunity levels of freshwater and marine organisms.
Jennet Orayeva, New Research on the Possible Effects of Micro-and Nano-plastics on Marine Animals