'Mermaid's Tears': The Rise of Microplastic Pollution

Plastic pollution is one of the few environmental issues well-documented by the media. I'm sure you've heard about how whales, turtles and seabirds have sadly become entangled in and ingested macroplastics, such as plastic bags, and subsequently died as a consequence. In fact, over 250 marine species are believed to be impacted by plastic ingestion (1). The world is currently unable to properly collect discarded plastics and because this plastic waste is so lightweight and durable, it is easily transported by wind and rivers to the coast (2). This combined with the rapidly increasing production of single-use plastic products, is why there is so much plastic in the ocean. In fact, plastic production has increased exponentially, from 2.3 million tons in 1950 to 448 million tons by 2015, and is even expected to double by 2050 (3).

The demand for plastic is so great because plastics have revolutionised our way of life. Plastic has allowed us to 'make space travel possible, lightened cars and jets—saving fuel and pollution -- and have saved lives with medical devices, helmets, incubators, and equipment for clean drinking water' (4). It's our carelessness and throw-away culture which is why plastic pollution has become one of the most pressing environmental issues. Currently, it estimated that 5.25 trillion pieces of plastic are in the ocean (5).

However, in this blog post I want to talk about another side of plastic pollution - something that is not as well covered by the media:

Microplastics.

Microplastics, colloquially known as 'mermaid's tears', are tiny plastics less than 5 mm big. Over the past 5 decades, the oceans have accumulated these microplastics, and now, they are found almost everywhere, on beaches, all the way from the surface waters, throughout the water column and within the seabed (6). They have even been found at the bottom of the Mariana Trench, the deepest trough (7). The amount of these microplastics varies on the location, but there are localised 'hotspots', including gyres (large systems of rotating ocean currents) and industrial coastal areas (6). The shape of these microplastics also vary from irregular fragments to spherules (like in the picture below), but fibrous microplastics are the most abundant in the marine environment (6). Microplastics are either purposefully produced by manufacturers (referred to as their primary origin), or are formed when macroplastics fragment into smaller pieces (referred to as their secondary origin) (6). The latter is how the majority of microplastics form, which is why we need to reduce our use of single-use plastics.

Microplastics I found on a beach in Kefalonia, Greece

Microplastics is a relatively new topic in science research, which is why there is not a lot of knowledge on the long-term effects these may have on marine organisms. In 2012, a technical report revealed that 11% of reported incidents between organisms and marine debris was associated with microplastics (8). It is assumed that this number is relatively low because these tiny bits of plastic are likely to pass through the digestive system and are expelled without consequence (4).

However, scientists are becoming more concerned about microplastics. This is because these tiny plastic fragments fit in the same size fraction as sediments and some planktonic organisms, and so are potentially bioavailable to a wide range of organisms, such as low trophic suspension, filter and deposit feeders, detritivores and planktivores (6).What this means is that these microplastics may be easily consumed by plankton (and other organisms near the bottom of the food chain) thereby entering the food chain. As a result, these microplastics can accumulate within organisms higher up in the food chain. This is problematic because these microplastics may cause a lot of physical harm, such as internal abrasions and blockages (6).

Another serious concern is that many pollutants and contaminants from manufacture (such as monomers and plastic additives) may leach from the microplastics causing toxicity in the organism, and potentially causing carcinogenesis and endocrine disruption (6). Not only do the microplastics leach toxic contaminants, they also adsorb and concentrate toxic compounds from seawater, such as hydrophobic persistent organic pollutants (POPs). Given that microplastics have a large surface area to volume ratio, they can become heavily contaminated with these pollutants and toxic compounds, whereby their concentrations may be up to a million times greater than ambient seawater (9). Through a process called biomagnification, concentrations of toxic compounds in larger animals higher up the food chain can become even higher still (6).

Consequently, microplastics do not only pose a problem for marine organisms that ingest them, they may also directly affect humans that eat seafood. This is because commercial species, such as cod, mullet, anchovies, and sardines have all been shown to contain microplastics. Additionally, consumers may be exposed to 1,800 - 11,000 microplastic pieces each year from shellfish consumption (10). Despite the effects of microplastics on humans are not yet known, and a risk assessment needs to be performed with regards to the toxic effect of microplastics (11), it is assumed that there will only be a small effect on exposure to contaminants. Nonetheless, microplastics indirectly affect humans through harming marine environments and the marine organisms living there, as they reduce their ability to carry out ecosystem services such as acting as a food supply, sediment nutrient cycling and primary production (12,13).

Given that microplastic abundance has been shown to increase with increasing human population-density (14), it is essential we start reducing our use of plastic. Progress is already underway as microbeads have been banned in beauty products since 2018, across the world (15). However, microplastics are found in virtually any product imaginable from razors to period products to food packaging. Even our clothes release microplastic fibres when washed. Whilst this is overwhelming, it provides us with a lot of ways to make easy changes to our lifestyle, and reduce this plastic pollution! Next time you're at the beach, you can even try to collect some of these microplastics (as well as larger macroplastics). It helps if you have a sieve to help you sift through the sand!

My friend is creating a forum where we can share our tips on how to reduce our plastic pollution. You can check out their website here. I will also be posting tips on how to live a more conscious and sustainable lifestyle! You can subscribe to my blog to make sure you don't miss these posts.

Sending out love,

NJB x

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References

1. Laist, D.W., 1997. Impacts of marine debris: entanglement of marine life in marine debris including a comprehensive list of species with entanglement and ingestion records. InMarine debris(pp. 99-139). Springer, New York, NY.

2. Thompson, R.C., Moore, C.J., Vom Saal, F.S. and Swan, S.H., 2009. Plastics, the environment and human health: current consensus and future trends.Philosophical Transactions of the Royal Society B: Biological Sciences,364(1526), pp.2153-2166.

3. Hasan, M., Kumar, A., Maheshwari, C. and Mangraj, S., 2020. Biodegradable and edible film: A counter to plastic pollution.IJCS,8(1), pp.2242-2245.

4. Parker, L., 2019.The World's Plastic Pollution Crisis Explained. [online] National Geographic. Available at: https://www.nationalgeographic.com/environment/habitats/plastic-pollution/ [Accessed 15 June 2020].

5. Eriksen, M., Lebreton, L.C., Carson, H.S., Thiel, M., Moore, C.J., Borerro, J.C., Galgani, F., Ryan, P.G. and Reisser, J., 2014. Plastic pollution in the world's oceans: more than 5 trillion plastic pieces weighing over 250,000 tons afloat at sea.PloS one,9(12), p.e111913.

6. Wright, S.L., Thompson, R.C. and Galloway, T.S., 2013. The physical impacts of microplastics on marine organisms: a review.Environmental pollution,178, pp.483-492.

7. Peng, X., Chen, M., Chen, S., Dasgupta, S., Xu, H., Ta, K., Du, M., Li, J., Guo, Z. and Bai, S., 2018. Microplastics contaminate the deepest part of the world’s ocean.Geochemical Perspectives Letters,9, pp.1-5.

8. Dias, B.F.D.S. and Lovejoy, T.E., 2012. Impacts of marine debris on biodiversity: Current status and potential solutions. Secretariat of the Convention on Biological Diversity and the Scientific and Technical Advisory Panel—GEF.Montreal, Technical Series, (67), p.61.

9. Teuten, E. L., Saquing, J. M., Knappe, D. R., Barlaz, M. A., Jonsson, S., Björn, A., Rowland, S. J., Thompson, R. C., Galloway, T. S., Yamashita, R. & Ochi, D., 2009. Transport and release of chemicals from plastics to the environment and to wildlife. Philosophical Transactions of the Royal Society B: Biological Sciences,364(1526), pp.2027-2045.

10. Van Cauwenberghe, L. & Janssen, C. R., 2014. Microplastics in bivalves cultured for human consumption. Environmental pollution, 193, pp.65-70.

11. [EFSA] European Food Safety Authority, 2016. Presence of microplastics and nanoplastics in food, with particular focus on seafood. EFSA J,14 (6), p.4501.

12. Green, D.S., Boots, B., Sigwart, J., Jiang, S. and Rocha, C., 2016. Effects of conventional and biodegradable microplastics on a marine ecosystem engineer (Arenicola marina) and sediment nutrient cycling.Environmental Pollution,208, pp.426-434.

13. Zhang, C., Chen, X., Wang, J. and Tan, L., 2017. Toxic effects of microplastic on marine microalgae Skeletonema costatum: interactions between microplastic and algae.Environmental pollution,220, pp.1282-1288.

14. Browne, M.A., Crump, P., Niven, S.J., Teuten, E., Tonkin, A., Galloway, T. and Thompson, R., 2011. Accumulation of microplastic on shorelines woldwide: sources and sinks.Environmental science & technology,45(21), pp.9175-9179.

15. GOV.UK. 2020.World Leading Microbeads Ban Comes Into Force. [online] Available at: https://www.gov.uk/government/news/world-leading-microbeads-ban-comes-into-force [Accessed 15 June 2020].