In this article we explain what microplastics are, and the dangers they present to the marine food web, animals and human health. We also discover what you can do to help solve the problem, and in the process reduce your carbon footprint and support biodiversity on the planet.
Plastic Waste and Pollution
Every year, we generate between 275 and 350 million tonnes of plastic waste, of which 100 million tons is mismanaged. Nearly 90 percent of this – 90 million tons – ends up in the ocean. It includes 5 trillion pieces of microplastic. 1
Plastic pollution has increased tenfold since 1980 and is now found in all parts of the ocean, from shallow coastal waters down to the bottom of the 36,000-foot Mariana Trench. (Source: IPBES 2019 Global Assessment Report.) It is eaten by nearly every creature in the sea, and so far has been found to block the digestive tracts of at least 267 different species. 1
After reports in the news media that skies were clearing all over China because of the coronavirus shutdown, some people thought that the pandemic might signal a permanent reduction in pollution, including microplastics. This now looks doubtful. See: Effect of COVID-19 on Climate Change.
By 2050, by which time the world’s population will be 2 billion more that today (2020), it is expected that plastic production will triple. By then, experts think that the amount of plastic in the ocean will weigh more than the amount of fish that swim in it. 2
- Plastic Waste and Pollution
- What Are Microplastics?
- Primary and Secondary Microplastic
- What Are The Main Sources of Microplastics?
- Where Are Microplastics Found?
- What Is The Problem With Microplastics?
- Are Microplastics Harmful To Ingest?
- How Do Microplastics End Up In The Ocean?
- What Should We Do?
What Are Microplastics?
The term microplastic refers to any piece of plastic that measures 5 mm or less in length. That’s about the size of a sesame seed. Microplastics occur when bigger pieces of plastic – such as bottles, bags and containers break down in soil or deep in the carbon reserves of the ocean. Even smaller again, are nanoplastics. These microscopic particles – often found in drinking water – measure less than 1/1000 of a millimeter.
Macroplastics = more than 25mm in length.
Mesoplastics = between 5-25mm
Large microplastics = between 1- 5mm
Small microplastics = less than 1mm
Nanoplastics = less than 1/1000 mm
Primary and Secondary Microplastic
Microplastics are classified in two ways:
- Primary Microplastic
This is a plastic fragment which is already 5.0 mm in size or less before entering the environment. Sources include microfibers shed from clothes and other textiles like fishing nets, as well as microbeads found in cosmetic scrubs and plastic pellets called nurdles used to manufacture plastic products.
- Secondary Microplastic
These are microplastics which occur from the degradation of larger plastic products after entering the environment. This breakdown can happen when plastic (a) is exposed to radiation from the sun (photodegradation); or (b) is knocked around by ocean currents (physical abrasion); or (c) is degraded by contact with water (hydrolysis); or (d) is attacked by microbes (biodegradation in the plastisphere). 3
Sources of plastics which degrade into secondary microplastics include plastic bags, water bottles, straws and fishing nets. Very often these microplastics end up in the hydrosphere, transported through streams and rivers into the ocean.
Did you know: The study of the microplastics involves a host of different sciences including: biology, conservation, ecology, earth science and oceanography.
What Are The Main Sources of Microplastics?
In addition to direct plastic waste – that is, the plastic bottles, wrappings, and bags that we dump – other sources of microplastics include:
The impact of cars on climate change is well known. Exhaust emissions spew greenhouse gases into the atmosphere raising global temperatures and causing air pollution of various types. Sadly, the problems do not end there. A recent study shows that microplastics released from car tyres and brake systems are a major source of marine pollution – much more than previously thought.
Every year, 100,000 metric tonnes of microplastics are shed from tyres, transported through the air and dumped in the ocean. Another 40,000 tonnes comes from brakes. 4
Skincare and hygiene products that contain microbeads, are another source. Fortunately many cosmetic companies are replacing microbeads with more natural ingredients like oatmeal, pumice and almonds.
Microfibres are another source of plastic pollution. Microfibres are tiny strands of plastics found in our clothes, which are released into the water system through production or washing, and through natural wear and tear. Many man-made materials like polyester, nylon, acrylic and polyamide contain plastic. 5
Aside from drinking water, microplastics are found in the dust of our homes and the air we breathe – they are shed from car tyres, soft furnishings, carpets, and the clothes we wear such as fleece jackets.
According to a study published in Lancet Planetary Health in October, 2017, the proliferation of microplastics in the environment is a concern, in part because the impact on human health is still uncertain. Even so, many countries are taking action to reduce microplastics. A 2017 United Nations resolution discussed microplastics and the need for regulations to reduce this hazard to our oceans, wildlife and human health.
Where Are Microplastics Found?
Everywhere. They are found in our oceans, in freshwater rivers and lakes, in the pedosphere and atmosphere and human food chain. They turn up in the deepest part of the oceans and stomachs of seabirds and whales.
Plastics degrade slowly, often over hundreds perhaps even thousands of years. This longevity increases the probability of microplastics being ingested and incorporated into tissues of many living creatures, big and small. The complete cycle and movement of microplastics in the marine ecosystem is not yet understood. Oceanographers are studying their impact on important blue carbon ecosystems, such as mangrove forests, as well as coral reefs and other fragile environments.
Newspaper headlines have focused on the ugly floating patches of plastic garbage in our oceans. These patches are created by the big five gyres – ocean currents whose circular flow causes plastics to accumulate in certain spots. The five gyres are the North- and South Pacific Gyres, the North- and South Atlantic Gyres, and the Indian Ocean Gyre.
However, the visible plastic pollution that gathers in the gyres, is thought to represent only 1 percent of marine plastic. So where is the other 99 percent?
Some of it has almost certainly been eaten by sea creatures, and birds who forage along the seashore. But we still have a very poor understanding of how much total plastic has accumulated in the oceans. Only one thing seems clear: most of that plastic is not floating on the ocean surface.
Scientists are still searching for answers, but it seems likely that most plastic has fragmented into tiny fragments and has fallen into the depths. There are fragile ecosystems on the ocean floor which rely on oxygen and nutrients being downwelled by the thermohaline circulation network of deep water currents. These currents are transporting microplastics to the same places that these fragile ecosystems exist.
Plastics have proliferated to such an extent in recent decades that their tiny remains – microplastics – are becoming a permanent part of Earth’s lithosphere in sedimentary rocks.
What Is The Problem With Microplastics?
The problem with microplastics – like all plastics – is that they do not easily break down into harmless molecules. Plastic is extremely durable. We don’t know how long it takes to decompose. Or even if it decomposes at all! For example, plastic bottles could take as long as 450 years to decompose and a plastic toothbrush 500 years. 6
Meantime, all that plastic is wreaking havoc on all life forms and here is how:
1. Human Health – We Are Ingesting Plastic
- Fish for Supper
Microplastics are small enough to be eaten by larger zooplankton and coral polyps, krill and filter-feeding mussels. As we move up the food chain, these marine creatures are consumed in huge quantities by bigger fish, thousands of whom are then consumed by even bigger fish. You can see how the concentration of plastics increases, by the time a fish ends up on our dinner plate.
- Fruits and Vegetables
According to a new study, even apples and carrots have high levels of plastic particles in them. How on earth does this happen? The answer is, through the water cycle. Microscopic fragments of plastic in the ocean are uplifted into the atmosphere in evaporating water vapor. Here they form clouds and ultimately return to earth in rainwater, which is absorbed by the roots of plants.
- Meat and Dairy
Researchers say that if plastics are getting into the soil, it means they are getting into our meat and dairy foods as well. 7
- Tap Water
According to a 2017 global drinking water study conducted by OrbMedia, an average of 83 percent of global tap water samples were found to be contaminated by microplastic pollutants. The United States led the field with a 94 percent rate of contamination. European countries, like the United Kingdom, Germany and France had the lowest contamination rate (72 percent). In 2020 the World Health Organisation (WHO) published a report on the impact of microplastics in drinking water. They concluded that the effects of microplastics on human health are unknown.
2. Animal & Marine Life Health
All animals, whether they live on land or in the sea, can be harmed by pieces of plastic. Each year, 100,000 animals in the sea are killed by them.
In the oceans, microplastic pollution is ingested by marine life from zooplankton and krill, up to seals and whales, with inevitable effects on the ocean ecosystem around the world. On beaches, microplastics are visible as tiny multicolored plastic bits in sand.
Animals can become trapped and choke on larger pieces of plastic like carrier bags and fishing nets. Birds, fish and shellfish can mistake microplastics for food. Their stomach becomes blocked, so there is no space for food and they starve. According to recent studies that examined marine species for pollution, pieces of plastic were found in marine turtles (100 percent), whales (59 percent), seals (36 percent) and seabirds (40 percent).
3. Plastic Worsens Climate Change
Plastic is also bad for climate change. According to a 2019 report “Plastic and Climate”, plastics production in 2019 generated 850 million tonnes of CO2e greenhouse gas emissions, the gases that are fuelling global warming. If this trend continues, these emissions will expand to 1.34 billion tonnes by 2030, and a whopping 56 billion tonnes by 2050. 8
What’s more, sunlight and heat causes plastic to break down and release methane, a particularly powerful greenhouse gas. This leads to an alarming feedback loop, increasing the rate of climate change, and so perpetuating the cycle.
Are Microplastics Harmful To Ingest?
Microplastics are found everywhere on Earth, yet we know surprisingly little about the risks they pose to living things. Scientists are still unsure whether ingestion of microplastics is harmful to human health—and if so, what specific dangers they may pose.
We say this because it’s technically true – there is no clear evidence yet that microplastics are harmful to our health. But how would you feel about having hundreds of small pieces of plastic whizzing around your arteries?
How Do Microplastics End Up In The Ocean?
They enter the sea through a variety of pathways. Some plastic gets into the sea from ships or shoreline litter, but the largest faction enters the sea as a result of rainwater runoff and sewer overflows. Winds that carry plastic and other forms of litter into our oceans, are another problem. This is one of the reasons that town planners are increasingly interested in developing sponge cities, a water sensitive design aimed at minimizing stormwater runoff in big population areas.
Research shows that as much as 90 percent of marine plastic debris enters our oceans through 10 of the world’s rivers. This does not mean that plastic is being dumped into those rivers directly, but because plastic is light and breaks down, it can find its way through the water stream from a landfill, into a river and ultimately an ocean. For example, in September 2020 the wall of a landfill in the suburb of Jakarta, Indonesia collapsed, sending 100 tons of garbage straight into the river Cisadane. Among the trash was a large amount of medical waste like plastic syringes, masks and hazmat suits used during the COVID-19 pandemic.
It is estimated that 20 percent of the Great Pacific Garbage Patch rubbish comes from ships and offshore oil rigs.
Via Transport and Distribution
Factories that produces plastic often end up leaking plastic through the production, transport or disposal process.
Down the sink or toilet
We flush it down the sink. A high profile example is that of microbeads, which are tiny plastic balls fall in exfoliants and shower gels. Also, sanitary products, cotton buds and face wipes. 9
Isn’t Plastic Recycled?
No, only a fraction of what we produce today is recycled. The rest ends up in our environment. It is coating our land and oceans like a disease. For example, according to the Plastic Pollution Coalition, of the 30 million tons of plastic that Americans throw away annually, only 8 percent is recycled. Of the almost 3 million tonnes of plastic that Australia produces each year, 95 percent according to the World Wildlife Fund, is discarded after a single use. Less than 12 percent is recycled.
What Should We Do?
What we need to do is dispose of our plastic waste more carefully, so that it doesn’t end up harming wildlife in the ocean. Each of us can help by not leaving waste on beaches and by buying fewer single-use plastic items like plastic water bottles and bags.
Switching to electric vehicles (EVs) is another way for us to reduce the amount of plastic pollution we create, as EVs shed far fewer plastic fragments than conventional internal combustion vehicles.
Lastly, we need to call out those companies or local authorities who don’t have a responsible waste policy.
Plastic straws – 200 years
Plastic straws can take up to 200 years to decompose.
Six pack plastic rings – 400 years
They can also be devastating to marine wildlife who get entangled and choak.
Plastic bottles – 450 years
An estimate 75 percent of water bottles are not recycled – they end up in landfills which increase methane emissions, litter roadsides and pollute the ocean.
Plastic cups – 450 years
The lining of plastic cups makes them more durable, but over time they release toxic chemicals into the environment
Disposable diapers – 500 years
They do not dispose well, clogging up landfills and contaminating groundwater. Opt for reusable cloth diapers or eco-friendly alternatives.
Coffee pods – 500 years
Those plastic pods are a serious eco-hazard. Avoid or use recycled pods.
- “Plastic Oceans.” Future Agenda.
- The New Plastics Economy, Rethinking the future of plastics. World Economic Forum. PDF. 2016
- Microbial Ecotoxicology of Marine Plastic Debris: A Review on Colonization and Biodegradation by the “Plastisphere” By Justine Jacquin. Microbiol. 25 April 2019
- Atmospheric transport is a major pathway of microplastics to remote regions. By N. Evangeliou, H. Grythe et al. Nature Communications volume 11, Article number: 3381 (2020).
- Could you be eating your own clothes? Friends of the Earth
- “The lifecycle of plastics.” World Wildlife Fund. 2018.
- Microplastics: Is there plastic in our fruit and veg? BBC June, 2020.
- Plastic & Climate: The Hidden Costs of a Plastic Planet
- Where did the Great Pacific Garbage Patch come from? November, 2018.