The Nitty Gritty on Microplastics

You’ve probably heard about the danger that microplastics can cause to our environment, and in particular to our oceans. You may even have seen media reports of fish or birds washed up with stomachs full of plastic. But what exactly are microplastics, why are they a problem, and what can we do about them? Crew member and marine scientist Kirsty Goode has the details.

What are microplastics and where do they come from?

Microplastics are defined as particles of plastic which are less than 5mm in size. There are two sources: primary and secondary. Primary microplastics include items like small pellets, beads and ‘nurdles’, which are used as industrial raw materials in the manufacture of plastic-based products. This includes everything from bottles and clothing (yes – there are plastics in our clothing!), to cleaning products and personal care additives. For example, most lipsticks contain polyethylene or polyethylene terephthalate, which is a plastic polymer that we ingest (in tiny amounts) throughout the day.

Secondary microplastics are created by the breakdown of manufactured plastic products due to processes like weathering, ageing, etc. Because plastic was designed to be durable and long-lasting, both primary and secondary plastics survive for centuries.

Why are microplastics a problem?

Both primary and secondary microplastics have been extensively found in virtually every environment on Earth, including the marine and freshwater environment and organisms within it; but also in soil, drinking water, table salt, even in the air we breathe. This means every organism on Earth is at risk of ingesting plastic in some form at some point in their lives, if not constantly. Since the early 2000s, scientific studies on the occurrence, distribution, and threats posed by microplastics have increased exponentially all over the globe.

From the increase in scientific studies, we have learned that the marine environment is at particular risk from plastic pollution, and human plastic production and consumption is not slowing. Because of human consumer-use patterns, plastic production increased from around 1.7 million tonnes in the 1950s to 100 million tonnes in 1990, to 380 million tonnes in 2020; showing increase at an exponential rate.

Furthermore, plastic globally is only recycled at a rate of about 9%. The other 91% ends up in landfills or sewage systems, and at some point much of it ends up in the ocean. It is estimated that globally 8 million tonnes of waste are discharged into the marine environment annually, with plastic making up 85% of marine litter. The most conservative estimates put the current number of circulating plastic particles floating on oceanic surface water at 5.25 trillion, while a more realistic estimate might be closer to 50 trillion, and that’s just what’s on the surface.

According to data from a 2015 plastics study published by the Ocean Conservancy in Science, alongside data from multiple assessments of global fish stocks, it is estimated that by 2025 there will be one tonne of plastic in the ocean for every 3 tonnes of fish, and that by 2050 there will be a greater mass of plastic in the ocean than fish biomass.

Who do microplastics impact?

In short, the answer is every living creature on the planet.

Within the marine environment specifically, NOTHING can avoid microplastics. Microplastics have been found in every corner of the marine environment and in the digestive tract or tissues of every organism which a scientific research project has examined. Microplastics have been found in every substrate, including rocky shorelines and beaches, seabed sediments, and at every depth. It has been found frozen in ice, floating on surface waters in the Arctic and inland on Antarctic ice, transported by ocean currents and wind.

Nearly every organism in the marine environment now ingests microplastics, either directly or indirectly, and that is because microplastics bioaccumulate. This means that if animals lower on the food chain (such as zooplankton or small bait fish like anchovies or pilchards) ingest plastic particles directly by mistake, they do not get digested. They linger in the tissues of the zooplankton or fish, and in turn are ingested by the pelagic fish, marine mammals, or seabirds which feed on them. This can result in harmful physical damage, like intestinal blockage and a false sense of satiation, which can cause an animal to starve or die of digestive complications.

If this wasn’t harmful enough, microplastics are also known to absorb or bond to toxic chemicals in the marine environment (some of which humans are also responsible for depositing into the ocean), thus bringing those toxic chemicals into the food chain. These toxins leach into the tissues of fish which have consumed them, causing hormone disruption and harmful changes in metabolism and physiology.

Because microplastics bioaccumulate, every animal in the marine food chain, including any land animals which consume marine species (AKA humans too!), is at risk of consuming microplastics in every mouthful. In fact, studies have found plastic particles in everything from wild-caught fish, crustaceans and shellfish at markets, to cans of salmon and tuna on supermarket shelves. It is estimated that through seafood consumption, humans ingest upwards of 40,000 microplastic particles per person per year.

What can we do to help?

The burden of reducing the harmful effects of plastic on the marine environment cannot be left for just the consumer. It is important to join the conversation about what larger corporations which consume and produce plastic can do to improve their practices, and what policymakers can do to help implement and regulate environmentally friendly manufacturing standards as well. As an individual though, there are a few things we can do to reduce our plastic demand:

Say no to single-use plastic products

This includes everything from plastic bags at the supermarket (which look a lot like a jellyfish to a marine mammal!), to unnecessary plastic packaging on consumables like fruit (which already have their own natural packaging!), to plastic straws from fast-food restaurants (we don’t need them to drink liquids at home, so why there?). Take your own containers to take-away places and coffee shops, and carry your own refillable water bottle. Small changes can make a big difference over time!

Start reading the labels

Choosing products which don’t use plastic in the production process may seem daunting, but it will help you to appreciate just how much there is out there. Educate yourself on the ingredients of your make-up products, and make the switch to those which do not contain plastic polymers or derivatives. Choose clothing made of natural fibres like cotton, silk, hemp, or wool instead of polyester or acrylic. If you can find housewares like dishes, cutlery, tools, toys, etc. made of natural materials like wood, choose those products. With every plastic item going unpurchased, retailers will need to restock it less, and manufacturers will be producing less.

Dispose of waste responsibly

This can be as simple as reading the labels of plastic that you do consume to make sure that it is disposed of in the proper recycling bin as appropriate. Pay attention to how much of what you consume fits into specific categories of waste, and try to take small steps to move toward more naturally biodegradable or compostable products – there are many more options than you may realise!

Get involved where you can

It may be difficult for some to find the time to join a beach, park, or community road clean-up, but getting involved doesn’t always have to take lots of time! It can be as simple as forming a habit to pick up one or two items of rubbish every time you walk through the park or on the beach. You might like to donate to a local event or charity which supports plastic-free efforts, or just hold friends or family accountable for not disposing of waste irresponsibly. There are tons of ways to improve the consumption habits of yourself and those around you, and you may surprise yourself at how easy it can be!

Sources

Auta, H. S., Emenike, C. U., & Fauziah, S. H. (2017). Distribution and importance of microplastics in the marine environment: a review of the sources, fate, effects, and potential solutions. Environment international, 102, 165-176.

Guo, X., & Wang, J. (2019). The chemical behaviors of microplastics in marine environment: A review.  Marine Pollution Bulletin, 142, 1-14.

Jambeck, J. R., Geyer, R., Wilcox, C., Siegler, T. R., Perryman, M., Andrady, A., … & Law, K. L. (2015). Plastic waste inputs from land into the ocean. Science, 347(6223), 768-771.

Mercogliano, R., Avio, C. G., Regoli, F., Anastasio, A., Colavita, G., & Santonicola, S. (2020). Occurrence of microplastics in commercial seafood under the perspective of the human food chain. A review.  Journal of agricultural and food chemistry, 68(19), 5296-5301.

Zhang, Q., Xu, E. G., Li, J., Chen, Q., Ma, L., Zeng, E. Y., & Shi, H. (2020). A review of microplastics in table salt, drinking water, and air: direct human exposure. Environmental science & technology, 54(7), 3740-3751.