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It is very difficult to remain unconcerned about plastic pollution after visualizing images of landfills or sea beaches covered with plastic bags, bottles, and other commonly used plastic materials. The harmful effects of minute plastic fragments, such as microplastics and nanoplastics, on marine creatures, terrestrial plants, birds, and human beings have become a much-discussed topic of the present day. This article discusses the harmful effects of both microplastics and nanoplastics, and the measures/technology adopted to tackle the problem.
Microplastics and Nanoplastics
Scientists have reported that the real potential hazards of plastics are in their fragmented forms (micro and nanoplastics). These minute plastic fragments are the result of the degeneration of large plastic materials. Plastic fragments smaller than a few millimeters in size are commonly known as microplastics. However, in the past couple of years, scientists have started using the term “nanoplastics” to describe the plastic particles less than a few micrometers in size. Generally, microplastics are plastic fragments of 0.1 μm−5 mm in size, whereas, the dimension of nanoplastics is 0.001–0.1 μm. These fragments are so minute that they are not visible to the naked eye or even under a simple optical microscope.
Mostly in the case of microplastics, one of the main potential risks is it being stuck in the guts of living organisms. However, for nanoplastics, it can easily penetrate the tissues and organs of an organism. In a recent study, nanoplastics have been reported to be present in the tissues of terrestrial plants, harming the ecosystem.
Harmful Effects of Microplastics and Nanoplastics
Scientists face immense difficulties in the study of nanoplastics, especially with regard to their occurrence and behavior. Denise Mitrano, Assistant Professor at ETH Zurich, and her colleagues have recently published their findings on monitoring the fate of nanoplastics in Nature Nanotechnology. In their study, the synthesized plastic nanoparticles consist of a metallic core which could be easily traced with commonly available analytical techniques used for metals analysis. Even though their research does not minimize the effects of plastic pollution, the possibility of the synthesis of metal-doped nanoplastics has very much opened the doors for accurate assessment (in laboratory conditions) of the extent to which nanoplastics pose a threat to our environment.
The harmful effects of microplastics and nanoplastics are mainly mechanical and/or toxicological in nature. When plastic pieces undergo leaching, they release chemicals that are carcinogenic in nature. Some of the chemicals produced after leaching, such as monomers, polymer-associated chemicals, and plastic additives adversely affect the endocrine system.
A team of researchers led by the IAEA has recently published a comprehensive review in the Journal of Environmental Science and Technology in 2020, discussing how often fishes consume tiny plastic particles (resin pellets used in plastics manufacturing) and its aftermath. The study revealed that the biological functions of these fishes that include their metabolism, neurological behavior, intestinal microbiome diversity, and intestinal permeability are greatly affected.
Marc Metian, a Research Scientist at the Radioecology Laboratory of the International Atomic Energy Agency (IAEA) and one of the co-authors of the above-mentioned study, remarked that accurate monitoring is highly essential for understanding the effect of these tiny plastic particles on various organisms. This is primary to design an effective model for environmental management and to develop mitigation strategies.
Some of the strategies include the determination of impacts at the cellular level that would ultimately affect the ecosystem. Scientists believe that formulation of novel degradable plastics that would not have any footprint in our environment would be a necessary step to resolve the problem of plastic pollution.
Read more: Tackling the Great Pacific Garbage Patch with The Ocean Cleanup Project
Removal and/or Elimination of Microplastics and Nanoplastics
Since the researchers discovered the adverse effects of microplastics and nanoplastics on the health and environment, they have become more focused on understanding the impacts of these materials and in providing possible solutions in reducing or eliminating these potential environmental threats. Some of the processes and technology used to decrease or eliminate microplastic and nanoplastics pollution are discussed below.
Reduction in the usage of plastic products
Treatments of wastewater and drinking water are found to be highly effective in the removal of microplastics. This technology showed a reduction of 90% of microplastics. Another measure to bring about a reduction in plastic pollution entails minimal usage of single-use plastic materials, for example, plastic bottles, plastic bags, fork, straws, and cups. Therefore, minor changes in lifestyle could bring about a great change in the environment.
Plastic degrading substance
Scientists believe that one of the potential options for reduction or elimination of plastic pollution is the use of microorganisms, such as marine fungus Zalerion maritimum and several bacteria. However, they showed maximum effectiveness in the degradation of microplastics. Similarly, it has been reported that PET polyester plastics undergo enzymatic degradation in a rapid and efficient manner.
The effect of filtration depends on the size distribution of the micro and nanoplastic particles. As expected, the process of removal of microplastics and nanoplastics through filtration is more effective with a decrease in the pore size.
The effect of centrifugation in the removal of microplastics and nanoplastics showed that the percentage removal increased significantly at centrifugation speed between 5000 and 7000 rpm with a gradual increase in time.
This process is typically used in the drinking water treatment for the removal of fine contaminants. It is also found to be effective in wastewater treatments. Recently, researchers found that this technology can be effectively used for the removal of microplastics and nanoplastics.
Microplastics and nanoplastics pollution have become a much more difficult problem to tackle owing to their size. Not only is there a need for a new effective technology for easy removal and elimination of the tiny plastic particles, but there is also a need to educate people about the problems related to the unmindful littering or unnecessary overuse of plastics.
References and Further Readings
Orayeva, J. (2020) New Research on the Possible Effects of Micro- and Nano-Plastics on Marine Animals. [Online] Iaea. Available at: https://www.iaea.org/newscenter/news/new-research-on-the-possible-effects-of-micro-and-nano-plastics-on-marine-animals (Accessed on 21 September 2020).
Murray, A., and Örmeci, B. (2020) Removal Effectiveness of Nanoplastics (<400 nm) with Separation Processes Used for Water and Wastewater Treatment. Water. 12, 635; https://doi.org/10.3390/w12030635
Nature Nanotechnology. Nanoplastic should be better understood. 14, 299 (2019). https://doi.org/10.1038/s41565-019-0437-7
Hargerbaeumer, A., et al. (2019) Impacts of Micro- and Nano-Sized Plastic Particles on Benthic Invertebrates: A Literature Review and Gap Analysis. Frontiers in Environmental Science. 7, 17. https://doi.org/10.3389/fenvs.2019.00017
Mitrano, D.M., et al. (2019). Synthesis of metal-doped nanoplastics and their utility to investigate fate and behaviour in complex environmental systems. Nature Nanotechnology. 14, 362–368. https://doi.org/10.1038/s41565-018-0360-