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PLASTIC POLLUTION
A threat to our ecosystems on a truly global scale
More than 300 million tonnes of plastic waste generated per year (1). Over 6.3 billion tonnes of plastic waste generated to date (1). 5.2 trillion pieces of plastic in the ocean (2). These are just some of the mindboggling statistics you may have seen regarding the scale of the plastic pollution problem.
The widespread scale of plastic pollution coupled with the effects of plastic on wildlife have ensured that in recent years, plastic pollution has received widespread media attention.
There are countless big numbers we could list here to illustrate how huge the problem is (check out the links at the bottom if you want to see some of these!), but here are a few reasons why plastic pollution poses a problem to us and the environment.
1) Large animals and plastics: entanglement and starvation
One of the more visible impacts of plastic pollution are the effects of larger pieces of plastic on animals, which may consume or become tangled in plastics. Turtles, marine mammals, and seabirds are among the eye-catching marine fauna regularly reported to become entangled or ingest marine plastics, whilst on land, the same problems can befall terrestrial animals. Entangled animals may suffocate/drown, sustain injuries, or starve as they are unable to move and find food. Animals that have ingested plastics may also suffer from the same problems, as well as becoming unable to feed as plastics cannot be digested.
Unfortunately, instances of entanglement and ingestion are not rare. For example, up to 90% of green turtles have been observed to have ingested plastic in some regions, whilst
2) Adsorbing and concentrating toxic chemicals
One of the lesser known problems with animals ingesting plastics is the fact that plastics can adsorb and potentially concentrate toxic compounds from seawater (3, 4). As well as the many pollutants from manufacture that may leach from the plastic, nano and microplastics can also concentrate toxic metals and pollutants from the surrounding sea water. As a result, concentrations of pollutants and toxic compounds in microplasticsmay be up to a million time higher than background levels (5). These tiny plastic fragments may be consumed by plankton and enter the food chain, but this not only poses a problem for the animals (eg plankton) that consume the microplastics. Through a process called biomagnification, concentration of toxic compounds in larger animals higher up the food chain can become even higher still (5).
3) SOIL
Although we almost exclusively hear about the impact of plastic in the marine environment, recent studies have also examined the huge input of microplastics into terrestrial environments. However, recent studies have found that at present, microplastic pollution on land are far higher than inputs to the marine environment- 4 to 23 times higher, depending on the environment (7). Given the scale of the problem in the marine environment, this is obviously huge- and just as in the marine environment, microplastics can have adverse effects on terrestrial environments and the animals living there (7, 8). This may occur through direct ingestion, toxological effects, or indirect effects on particle environments (7, 8, 9), at environmentally relevant microplastic concentrations.
4) Microplastics MASSIVELY affect humans.
Just supposing you don't really care about turtles and whales, soil or earthworms, and only really want to know whether how microplastics affect humans- they do, in many ways.
Firstly, the direct effects- consumption of microplastics by animals has meant microplastics in our foods, especially seafood, are widespread (10). For example, raw mussels have been found to contain on average 6.2-7.2 pieces of microplastic for every g of raw mussel tissue (though this may be slightly reduced by cooking) (11). Depending on shellfish consumption, consumers may be exposed from 1800-11000 microplastic pieces each year (from low consumption to high consumption countries) (12).
It's not just shellfish either- commercial species such as cod, mullet, anchovies, and sardines have all been shown to contain microplastics. Whilst it should be stressed that the effects of microplastic consumption for human may only have a small effect on exposure to contaminants, data is lacking for a human risk assessment (European Food Safety Authority, 2016). Given our knowledge of toxic effects in other species, microplastic pollution is still therefore a concern.
Plastics also indirectly affect humans through harming natural environments and the organisms that live there, reducing their ability to carry out "ecosystem services". Broadly, these services describe any direct or indirect benefits we may derive from the environment, organisms living there, or interactions between these.
Whether this service is a food supply, sediment nutrient cycling and primary production (13), or improving soil quality (14), plastic pollution that has been implicated to affect all of these provisions.
These days, plastics can be found in virtually any product imaginable: from our clothes to razors, period products to food packaging. Whilst this is obviously a concern, it does provide us with a lot of ways to make easy changes to our lifestyle, and reduce this pollution!
Head to the forum to read and contribute suggestions and tips to reduce our plastic wastage!
SOURCES
Thanks for reading. Here I've attached the sources I referenced here with a brief description of each study. I've also included a "more info" section at the bottom where I've attached some easier to read news articles and sites, along with the statistics.
Very interesting global analysis about the fate of plastic production. Lots of big-hitting stats and be sure to check out the supplementary material for some of the data and lots of interesting figures
2) Eriksen, M., Lebreton, L. C., Carson, H. S., Thiel, M., Moore, C. J., Borerro, J. C., Galgani, F., Ryan, P. G. & 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.
A modelling study that estimated from 24 different expeditions around the world's oceans the number of plastic pieces in the ocean. Makes the headline 5.25 trillion particles estimate. Also if you've a more academic interest, there are the discrepancies of particle size distribution from expected values and the authors suggest mechanisms for removal of microplastics from the surface...
3) Gregory, M. R., 2009. Environmental implications of plastic debris in marine settings—entanglement, ingestion, smothering, hangers-on, hitch-hiking and alien invasions. Philosophical Transactions of the Royal Society B: Biological Sciences, 364(1526), pp.2013-2025.
A very nice summary of some of the problems associated with marine plastic pollution (including some I haven't even mentioned here)!
Comparison of sorption rates and concentrations of 2 classes of contaminants onto the 5 most common types of plastic
(Hard reading) A modelling study examining the potential for various plastics to accumulate contaminants and transfer them to organisms.
6) Rochman, C. M., 2015. The complex mixture, fate and toxicity of chemicals associated with plastic debris in the marine environment. In Marine anthropogenic litter (pp. 117-140). Springer, Cham.
A chapter from "Marine Anthropogenic Litter": if you're interested in marine plastics have a read of this. It's a book by Springer (academic publishing) so it contains a summary of different areas of research and often slightly less jargon than the original papers as well. So, if you're not a fan of the original papers as they can be quite jargon-y, this might be easier.
7) Horton, A.A., Walton, A., Spurgeon, D. J., Lahive, E. & Svendsen, C., 2017. Microplastics in freshwater and terrestrial environments: evaluating the current understanding to identify the knowledge gaps and future research priorities. Science of the Total Environment, 586, pp.127-141.
An estimate of the abundance of microplastics in terrestrial systems, and potential ecological consequences.
Also highlights the ecological effects of microplastics in soils, with several useful references to specific studies evaluating the influence of microplastics on different species/taxa.
9) Boots, B., Russell, C.W. & Green, D.S., 2019. Effects of Microplastics in Soil Ecosystems: Above and Below Ground. Environmental science & technology, 53(19), pp.11496-11506.
One example of a growing number of experimental studies that have observed negative effects of microplastics on soil and the fauna/flora living there.
A great review paper of the presence of microplastics in food- Table 1 can serve as a directory to previous studies of microplastics in different species. Also touches on possible consequences for human health.
Examining microplastic content in mussels and the effect of cooking them!
12) Van Cauwenberghe, L. & Janssen, C. R., 2014. Microplastics in bivalves cultured for human consumption. Environmental pollution, 193, pp.65-70.
Another study looking at mussels, and also estimating exposure to microplastics in humans.
Example of the effect of microplastics on primary productivity and nutrient cycling in marine sediments- through effects on lugworms!
14) Sarker, A., Deepo, D. M., Nandi, R., Rana, J., Islam, S., Rahman, S., Hossain, M. N., Islam, M. S., Baroi, A. & Kim, J. E., 2020. A review of microplastics pollution in the soil and terrestrial ecosystems: A global and Bangladesh perspective. Science of The Total Environment, p.139296.
Review of the effects of microplastics on soil properties and plant growth.
MORE INFO
As promised, a few more links to statistics or media articles with less jargon than the scientific papers:
Links to stats on the scale of the problem:
Our World in Data: https://ourworldindata.org/plastic-pollution
Lots of statistics on the scale of plastic pollution from scientific literature, summarised in a more visually appealing and accessible way.
SAS: https://www.sas.org.uk/our-work/plastic-pollution/plastic-pollution-facts-figures/
More stats from Surfers Against Sewage (SAS) about the scale of the problem.
Easy to read article about a study into chemical contaminants from plastics in seabirds. Also links to previous articles about microplastics in whales and other large filter feeders
A guardian article which simplifies some of the findings of (9) with less jargon
Disclaimer: This article was written by a page admin. Every effort was made to thoroughly research all topics with peer-reviewed literature when compiling this factfile. However, if you have any insights you would like us to add, or spot any inaccuracies, please feel free to contact us so we can amend this page. Thanks!