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Microplastics: what they are and how you can reduce them
Microplastics are one of the greatest manmade disasters of our time. They are everywhere - from remote places with no human habitations for hundreds of miles to the food on our plates and the water we drink.
So how dangerous are microplastics and what can we do to help reduce them?
What is microplastic?
Microplastics are plastic pieces that measure less than five millimetres.
Some microplastics have been made small intentionally, for example industrial abrasives used in sandblasting and microbeads in facial scrubs. Others have formed by breaking away from larger plastics such as carrier bags which have fragmented over time.
Where do microplastics come from?
Natural processes including sunlight cause plastic to become brittle, fragment and break.
But fragmentation doesn't stop there: microplastics can keep breaking up until they are like dust particles. This is called nanoplastic, and it's difficult to measure as it is impossible to separate from the environment.
'Microplastics are everywhere,' says Alex McGoran, London NERC DTP PhD student at Royal Holloway and at the Museum. 'They're in the water, soil and the air we breathe.
'We use plastic in almost everything, including chairs, carpets and clothes. As we move around, we shed fibres which float in the air and spread. They've even been found in places we previously thought were pristine, like the Arctic and Antarctica.'
Microplastics have been found in the Arctic, which had been considered one of the last remaining pristine parts of the world. Scientists suspect microplastics were blown through the atmosphere by wind and settled once it snowed.
Microplastics in water
There have been many concerns about microplastic in drinking water. A recent report by the World Health Organisation (WHO) gathered data from 50 studies to clarify how serious this may be.
Microplastics enter the water system from two main sources.
1. Run-off from land-based sources which include:
- landfill
- the breakdown of road-marking paints
- debris from tyre wear
- abrasion of synthetic products such as footwear and artificial turf
- agricultural run-off, particularly sewage sludge and agricultural plastic such as mulching
2. Wastewater overflow (both treated and untreated), including:
- microplastic fibres released when washing synthetic clothes
- breakdown of larger plastics in river catchments
- cosmetic microbeads
- fragments of large products that are flushed down the toilet when they shouldn't be, such as sanitary pads and wet wipes
Other sources of microplastic in water include atmospheric pollution, sewers and industrial overflows. Everyday occurrences also contribute, such as degrading construction materials and clothes drying on a washing line.
Are microplastics harmful?
Microplastics pose a risk to humans in three different ways: physical, chemical and as a host for other microorganisms to gather and breed on.
It is difficult to assess the risks microplastics may pose for humans as each plastic is made up of a unique combination of chemicals. Plastics also come in different shapes, sizes and textures, all of which influence their toxicity.
The same substance can have different effects depending on the concentration and how a person has been exposed to it - for example, whether plastic were consumed, inhaled or injected. The rate at which the chemical is released depends on the interactions between the chemical and the plastic as well as its location in the body.
A Hula Hoop packet dated August 1986 found in the River Thames. Nearly all the colour has left the plastic packaging, leached into the environment. © Alex McGoran.
Although research on plastics in animals presents a bleak outcome, there is little study undertaken on plastics in the human body.
Research on microplastics by the Food and Agriculture Organisation of the United Nations (FAO) and European Food Safety Authority (EFSA) concluded that large microplastics were likely to be excreted directly through faeces. In addition, the absorption of nanoplastics and chemicals found in plastics, including absorption into the organs, was limited.
Alex says, 'There is no doubt that microplastics have a negative effect on the human body, but whether they stay in our system long enough to have a severe effect is uncertain.'
There just isn't enough concrete evidence to know for sure whether microplastics in drinking water are a danger to humans and more research is needed.
How do washing machines contribute to microplastic pollution?
A lot of the clothes we wear are made of plastics such as polyester, nylon and acrylic. Every time we wash our clothes in the washing machine, millions of microfibres are shed. It is estimated that one load of clothes in a washing machine releases about 700,000 fibres per wash.
A microfibre is a tiny piece of plastic used in clothes and is thinner than a strand of hair. It passes through washing machine filters and water treatment plants, and ends up in rivers and oceans.
When in water, plastic acts like a sponge and absorbs chemicals. Some of these chemicals are products that escaped into the oceans years ago such as DDT, a pesticide which is now banned.
Many of those fibres are consumed by animals at the bottom of the food chain, such as plankton and mussels. Scientists predict it then accumulates up the food chain until it reaches us - although this still needs to be researched.
A lot of the plastic pollution is also dispersed by wind and ocean tides, spreading everywhere. So it's not just a local problem, but a global issue.
Many low- and middle-income countries do not have wastewater treatments, so microplastic is more likely to exist in greater quantity there. However, health risks associated with pathogens in untreated water pose a greater threat. By addressing the bigger problem, communities can manage both at the same time. Image courtesy of Balaram Mahalder/wiki (CC BY-SA 3.0)
How to reduce microplastics
Wastewater and drinking-water treatments are highly efficient in getting rid of microplastics. Studies, albeit limited, show they remove more than 90% of microplastics.
But there is a lot that individuals can do to reduce microplastics too. Perhaps the most important step lies in changing the way we think and behave.
Modern lifestyles are full of single-use plastic items such as straws and cups. It is thought that we use plastic cutlery once for an average of three minutes, but it remains in the environment for hundreds of years. Single-use plastic, including food packaging, is also one of the biggest contributors to plastic pollution.
Thinking about how plastic is made and what happens to it after it has been used makes a difference.
'We need to ask ourselves if we really need to use some types of plastic, like disposable forks,' says Alex. 'And if we do, we need to question how we are responsible for it and how we can dispose of it in the best possible way. It only takes a few seconds.
'An example of this is accidental littering. People may throw their rubbish in an overfilled bin, thinking they've done their part and the rubbish collectors will take care of it from there on, but all it takes is a gust of wind to knock it over and then you've got rubbish everywhere. So while it may be well-meaning, it's not responsible disposal.
'Responsible disposal might be that you end up taking the rubbish home with you so you can recycle it properly. It's different for each situation and individual.'
Plastic fibres and a balloon fragment found inside the stomach of a Chinese mitten crab from the River Thames. Mitten crabs have teeth-like structures in their stomach, which grind up food into mush. Fibres get tangled in dense knots that eventually fill up the whole stomach and are unable to pass through the digestive system normally. © Alex McGoran.
It is also essential to consider the importance of different types of plastics in our lives and the impact it would have if we removed them.
Plastic offers many benefits, for instance preventing infections by using plastic syringes and tubes in hospitals and prolonging the shelf life of some food. Care needs to be taken when removing or minimising plastic so that it doesn't just create a new problem.
'It's a complicated issue woven into climate change,' explains Alex. 'For example, if we exchanged plastic sachets with glass jars for pasta sauce, there would be less pasta sauce transported at one time. This means more journeys would need to be made to meet the demand resulting in further carbon emissions.
'Or if we changed to organic clothing, the land and water use needed to grow cotton would be immense.
'It is therefore a case of pairing alternatives and trying to figure out what the best solution is for each case.'
