Microplastics: The Snowflakes of the Plastic World
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Microplastics litter every corner of the globe, even the once-pristine landscape of the Antarctic. These tiny particles originate from larger pieces of plastic, degraded and worn down over the years until they measure just millimeters – or even less – in diameter.
While some plastics end up in landfill or are incinerated, most unrecycled plastics are destined for the oceans where they contaminate the marine ecosystem, and – although we can’t say with absolute certainty – potentially the food chain.
Plastics have been under scrutiny since the 1960s when debris was first documented in the oceans. Since then, there’s been an abundance of research into the detrimental effects plastics and microplastics are having on the environment, and the damage they could have on animal and human health.
Microplastics are “uninvited guests”
“Microplastics are a bit of a ‘catch-all’ term for small particles of plastics that are less than 5 mm long or a little than a quarter inch,” says Dr. Christopher Reddy, a chemist and oceanographer from the Department of Marine Chemistry and Geochemistry at Woods Hole Oceanographic Institution in Massachusetts, and author of Science Communication in a Crisis: An Insider's Guide.
They’re a bit of a challenge; there is no “typical plastic”, nor does a singular definition or description of plastic exist. Reddy compares microplastics to snowflakes – each one is different: “There is a wide range of plastics produced – all of which are different beasts. Some float on water; some don’t. On top of the different polymers, there is a wide range of additives (color, strength, flame retardants, etc.,) in plastics that carry their own risk. Then you have different sizes and shapes, which are affected differently by weathering and environmental breakdown. Lastly, plastics in the environment can act like sponges and pick up other contaminants.”
Reddy describes microplastics as uninvited guests, an ever-changing enemy representing one of the biggest environmental threats, particularly to the oceans. “For the most part, these small pieces are fragments of some plastic article like a plastic water bottle, cup or bag,” says Reddy. “Some combination of exposure to sunlight, abrasion and other weathering leads to them. Hence, they are unintended products.”
Microbeads are another uninvited guest found in cosmetics and personal care products; these small, solid manufactured plastic particles are added to beauty products like cleansers and toothpaste as an exfoliant or abrasive. They were first used around 50 years ago so they’re not a new problem, but we’re only just beginning to realize the damage they may be causing. Microbeads do not degrade or dissolve in water, yet many are too small to be captured by wastewater filtration systems, so they end up in our rivers, lakes and oceans where they pose a threat to aquatic life. But there is some good news: in 2015, President Obama passed the Microbead-Free Water Act, which banned the use of microbeads in personal care and cosmetic products.
Another major source of plastic pollution is nurdles or pellets. These are raw materials or pre-production ingredients for items such as plastic bags - and they’re found everywhere in the world, namely through poor handling during shipping and delivery. As early as 1972, scientists knew these nurdles, or spherules, were becoming problematic in the aquatic environment after finding them on the surface of the Sargasso Sea.
Microplastics; a persistent problem
Microplastic pollution is a chronic issue, Reddy says, describing it as trickling faucets worldwide as opposed to a massive release of plastics, and is an issue that must be tackled.
The root of the microplastics issue is their persistence; they remain in the environment for several decades – hundreds of years even – and degrade very slowly, breaking up into ever-smaller pieces.
Most microplastics originate on land and are carried by rivers and wind to the ocean, where they get caught up in the global ocean circulation system. The National Ocean Service, part of the National Oceanic and Atmospheric Administration (NOAA), say plastics are the most prevalent type of debris in the oceans and Great Lakes; they’ve also been discovered on beaches worldwide, on the ocean floor and in sea ice in the Arctic. Synthetic microplastic fibers have also been found in air, seawater sediment, and sea ice samples taken from the once-unspoiled Weddell Sea, one of the most isolated regions of the Antarctic.
“Microplastics have many origins, but it is the breakdown product of plastic wastes brought about mostly by disposed single-use plastics, packaging, garbage, etc., that starts from city and rural sources and ending in rivers, landfills and finally the ocean,” explains Rigoberto Advincula, Governor’s Chair Professor at Oak Ridge National Laboratory and the University of Tennessee, Department of Chemical and Biomolecular Engineering.
Microplastics are also present in public water sources where they have undergone many cycles of mechanical, biological and environmental breakdown, and they ultimately accumulate in marine organisms like fish and shellfish, he says. Microplastics have been found in the stomachs of different marine wildlife, from the smallest species of plankton to large whales, in the digestive tract of benthic invertebrates and in scat samples from penguins. They’ve also been found in the air, tap water, sea salt, bottled water, beer and the fish that humans eat – but we don’t yet know enough about the danger they may pose to human health.
Although we’ve known about the potential dangers of plastic pollution since the 1960s and 70s, early research consisted of one-off papers, meaning there was not enough understanding of the distribution and behavior of microplastics in the environment.
It’s only in the past decade or so that there have been more directed and diverse types of research on plastic pollution, including microplastics, providing access to large-scale, long-term comprehensive data. As the field matures, thanks in part to increased funding, it’s beginning to develop and recognize standard reference materials and create a common language about the amount and distribution of plastic in laboratory and field samples.
The NOAA Marine Debris Program is helping to grow the data; it has developed standardized field methods for collecting sediment, sand and surface water microparticle samples. These methods are under constant scrutiny to develop field and laboratory tests robust and accurate enough to enable global comparisons of the number of microparticles in different environments – a vital first step in determining the final distribution, impact and fate of microplastics.
The National Centers for Environmental Information Marine Microplastics Portal also gathers data on the occurrence, distribution and quantity of global microplastics in marine environments. This information can be used to improve water quality and protect Earth's ecosystems.
But exactly how do scientists test for the presence of microplastics? Professor Advincula, a polymer chemist whose research involves synthesis, fabrication and analytical work on all types of plastics materials, explains: “Detection is done by accumulation in marine life and directly from the sea – collection of samples and statistical analysis – using chemical spectroscopic and microscopic analytical methods. Plastics are mostly based on polyolefinic (PE, PP, PS) and PC, PET and nylon thermoplastics. From our instrumentation and methods, we can detect microplastics using methods like infrared (IR) spectroscopy, gas chromatography-mass spectrometry and pyrolysis methods and nuclear magnetic resonance spectroscopy. The study of microplastics, model samples and breakdown products from plastics to particles is done by many scientists worldwide.”
However, despite the progress being made, there’s still some way to go as scientists are unable to say with absolute confidence exactly what effect microplastics are having on ecosystems and their inhabitants.
“This lack of certainty in the measurement creates tremendous amounts of uncertainty on scaling the negative impacts of plastic pollution,” says Reddy. “The field is maturing, and we are on a trajectory of greater certainty, but scientifically it would be a whole lot nicer to have more certainty in measuring plastics!”
That’s not to say that plastics and microplastics aren’t bad, he adds, we just don’t have a full understanding of microplastic exposure and can’t say with enough level of confidence to make a definitive statement about their impact. As a result, scientists take a precautionary approach to plastic and err on the side of caution.
“While plastics are generally harmless as bulk materials and are essential to modern society (think about containers, food packaging, furniture, cars, toothbrush, bottles etc.,), their effect in the body as particles is just beginning to be understood,” says Advincula. “Since they are not normally biodegradable and also made of various compositions, their size (micro to nanoparticles) is a concern since they can remain as part of the digestive system of any living organism.”
It is difficult to create a generalized statement about microplastics’ effects, and even if we can eventually, it’s going to take time. Reddy uses the example of elemental lead as a comparison: over the years, scientists have gathered vast amounts of data on how it affects the human body and developed tests to determine how much there is in a person’s blood. Now, we can say with great confidence that lead affects neurological development in children, causing slowed growth, learning and behavior problems and hearing and speech issues.
Humans may be exposed to microplastics in several ways – ingestion, inhalation or dermal contact – but how these microplastics then affect the human body is poorly understood. Possible adverse effects include oxidative stress, cytotoxicity, neurotoxicity, immune system disruption and transfer of microparticles to other tissues after exposure, hypersensitivity, hemolysis, inflammatory lesions, possible metabolic disturbances and an increased cancer risk. However, there remain large gaps in our knowledge, so we cannot say with absolute certainty what effects microparticles are having on human health as Reddy emphasizes: “We don’t have the data yet and with time the field will gain more confidence.” He adds, “But microplastics look ominous so we should do something about it. And we should re-evaluate the situation as more data becomes available and the science improves.”
Countless papers are being published every day on plastic pollution – almost too many that Reddy believes it’s impossible to keep up. The sector is oversaturated with publications, which range in quality, and it’s hard to fully understand and evaluate the current situation.
“It’s also difficult to say with great confidence if the plastics being tested in the labs are truly representative of true exposure (think snowflakes and that we cannot accurately measure plastics in blood, etc.,). With time, we will know more,” say Reddy. “I am not an apologist for plastic pollution and spend half of my research time on plastics. But it is critical to communicate what we know, don’t know, what is changing and what is under debate.”
Plastics need a built-in Achilles heel
Edward Carpenter, a scientist at Woods Hole Oceanographic Institution, laid the foundation for plastics research. His work, published in 1972, revealed the presence of small particles of plastic on the surface of the Sargasso Sea, and spherules in the coastal waters of southern New England, which he suggested could lead to intestinal blockages in fish if ingested.
Since then, research has revealed the accumulation of plastic in the North Atlantic subtropical gyre, the presence of plastic particles in open ocean filter feeders such as zooplankton, in fish and prawns, and microplastics in the environment of the once-pristine Antarctic and its inhabitants.
Yet we’re still making plastics and pollution is a growing problem. Plastics are so ingrained in our lives that it would be virtually impossible to find a suitable replacement for each and every one or to remove them from our lives completely. We made too good a product and must use what we know about current plastics to build new plastics capable of fulfilling the same qualities and “we need to make them ‘just good enough’,” says Reddy. “They need to have a built-in Achilles heel that nature knows how to attack so they can’t persist.”
We must also tackle the plastics and microplastics already in the environment. The problem is that, just like no two snowflakes are the same, no environments are exactly the same. There is no one-size-fits-all solution. Instead, it requires a multi-pronged approach, tackling plastic pollution in several different ways.
It’s estimated that there are 5 trillion pieces of plastic litter situated in five garbage patches in the oceans, and this needs to be cleaned up before it degrades into microplastics, which are inevitably harder to remove from the water. Several years ago, there was a big push to remove plastic from the blue ocean – essentially big nets cast to catch plastics – but it became clear that it would be safer and more effective to catch it at the source, in the rivers and streams before it even reaches the ocean.
The Ocean Clean Up is a not-for-profit foundation consisting of 120 engineers, researchers, scientists and computational modelers whose technology aims to remove plastics from the oceans and at the source – the rivers.
In the oceans, their barrier technology creates an artificial coastline where large and small plastic becomes concentrated and therefore easier to remove. Computer modeling predicts where a plastic hotspot is likely to be, allowing a targeted clean-up operation, followed by recycling of the plastics.
They use similar technology along the rivers; a barrier guiding waste towards a catamaran-style vessel, which collects and extracts the plastic waste for recycling. A different type of barrier can also be deployed directly at the mouth of the river to stop waste until it can be removed.
Many other companies and organizations are also working to clean up the rivers and oceans, including Mr. Trash Wheel, which collects plastic debris from several rivers in Baltimore, and FRED, which sucks in debris measuring between 5mm and 5m from the ocean’s surface.
But we must also stop any further pollution – we need to close the leaky faucet. Many of us already recycle our plastics or have switched to plastic-free alternatives, but it’s going to take a wholesale change at a government level to have an impact. Many countries are bringing in legislation to help tackle plastic waste – Obama’s banning of microbeads being one example – by banning single-use plastics like cutlery and takeaway boxes or incentivizing recycling by offering vouchers or tokens for returning empties.
Reddy is hopeful about the future of plastics. He believes a collective effort to tackle the problem of plastic pollution now will lead to fewer problems in the future and that we could be on the right path within the next 10 to 20 years.