Microplastics, as the name implies, are tiny particles of plastics, created either for commercial use (primary microplastics, e.g. for use in cosmetics), from the breakdown of larger plastics (secondary microplastics), measuring 5mm or less in diameter. Over the last few years, there has been a lot of light shone on the prevalence and environmental and health impacts of microplastics, from their presence in drinking water, to their ubiquity in the ocean.

It has long been known that plastics never really break down – instead, they break up into ever smaller pieces, causing environmental damage at every stage of the process. Single use plastics are thought to be the foremost contributor to secondary microplastics, but many microplastics are created intentionally to be used in industry. Wastewater treatment cannot filter out all microplastics, so they end up everywhere – in our oceans, freshwater systems and even the air we breathe.

Understanding the leading causes and relative abundance of microplastic in our ecosystems is key to understanding the how this might affect us, our environment and how best to limit that damage. With the problems being multi-fold – impacting both the environment and out health – we need solutions sooner rather than later, before irreversible damage is done.

For a summary of this article, scroll to the bottom.

What are the major causes?

A 2017 study found microplastics in 81 per cent of tap water samples globally. In the past few years, in mountain ranges in the US and France, researchers even found microplastics in rain. They have recently been found in the Arctic, too, giving an indication of their ubiquity. So where are these microplastics coming from? Without knowing the key sources, it is impossible to begin to understand how to tackle the problem. Here are the two key ways microplastics get into the environment.

• Runoff from land-based sources, such as agriculture, tyre wear on roads and landfills.
• Wastewater overflow, including treated water, as treatments cannot always capture such small particles. The microplastics come from the washing of clothes (microfibres), cosmetic microbeads, flushed period products etc. 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. Washing machine filters are not currently able to filter out these microfibres, so they work their way into our water systems.

What are the environmental impacts?

Environmentalists will be no strangers to images of seabirds with plastics filling their stomach, but do microplastics cause the same harm? The science suggests that the environmental impacts can be severe and far-reaching, with microplastics being found in 47% of Fulmar guano samples (a good indicator of their presence in marine environments).

The potential issues are multifold. As plastics do not degrade, they accumulate both with ecosystems and up food chains. They can also absorb toxic chemicals and pathogens, providing another route of harm. Another issue is that for many organisms, ingested plastics can make them feel full, so they stop eating and eventually die of starvation.

“Microplastics have been found in a wide variety of species including zooplankton, mussels, oysters, shrimp, marine worms, fish, seals, and whales. Several of these species are of commercial importance. For example, a 2009 survey in the Clyde Sea found 83% of Norwegian lobster contained plastic, mainly in the form of fibres. Similarly, trawls in the English Channel found microplastics in 36.5% of fish caught” (DEFRA).

Further to their effect on animals, microplastics have the potential to carry around pathogens and invasive species. High levels of microplastics on beaches may even change the temperature of the sand, affecting animals such as turtles where offspring sex is temperature-determined.

Despite the complex science, a 2017 United Nations resolution discussed microplastics and the need for regulations to reduce this hazard to our ecosystems. The problem is so widespread it’s unlikely to not be seriously harmful over the years, and combined with the other pressures on our oceans, they need all the help they can get.

Are they causing us any harm?

There is a huge absence of science in this area, thanks in part due to the relative recency of interest in the subject, but also due to the difficulty of carrying out robust scientific studies on humans. It is estimated that the average person consumes up to 120,000 particles of microplastic each year, with that number increasing for those drinking mostly bottled water. However, whether or not this has had adverse effects in the decades we have been consuming them is not entirely clear.

As with many environmental issues, our exposure to microplastics is partially dependent on where we live. In the UK and other high-income countries, sewage treatments can effectively remove most microplastics from effluent, reducing the amount present in freshwater systems. In low and mid-income countries, however, only 33% of the population have sewer connections, meaning that for most of the population, water is poorly treated, leading to greater microplastic concentration in soils and water systems, and thus greater potential adverse health incomes.

For the most part in richer countries, drinking water is treated enough to prevent large quantities of microplastics working their way in. However, the smallest plastic particles can assimilate their way into our food, including seafood (primarily shellfish). While most plastics are inert (don’t readily react) and insoluble and therefore unlikely to be absorbed into our bodies, there are concerns about their absorption of toxic chemicals from the environment. However, with the relative paucity of scientific studies on the subject, there is not enough evidence to suggest a link between microplastics in drinking water and food and adverse health outcomes. This doesn’t mean that the link is not there, simply that more studies need to be done in this area.

What can we do?

• Reduce littering and improve rubbish collection systems.
• Move on from the idea that plastic is disposable. With the average single use cutlery being used for just 3 minutes, yet taking hundreds of years to break down (not disappear), this will never be a sustainable attitude.
• Install and optimise wastewater treatments which reduce the amount of plastic pollution in waterways, and thus the amount being consumed in drinking water too. While the UK has extremely effective treatment facilities, this isn’t the case everywhere.
• Limit the introduction of new plastic sources into the environment. A lot of microplastic pollution comes from single-use plastics in one form or another, so by reducing the amount of plastic we consume, we can reduce the amount that eventually ends up in our ecosystems.
• Improve plastic recycling systems and use them. Of the 8.3 billion metric tons of plastic that has been produced (2018), 6.3 billion metric tons has become plastic waste, and 91% of this has not been recycled. By reducing the amount of plastic sent to landfill we can reduce the amount of plastic breakdown there is globally. This includes dealing with our own plastic problem, and not shipping it elsewhere (just another form of environmental racism)
• Introduce global bans where possible on unnecessary use of microbeads (already done in the UK), for example in cosmetics, while recognising that this is only a small part of the issue.
• Improve sustainable plastic alternatives. While current ‘bioplastic’ alternatives are not always less harmful than conventional plastics, existing technologies have the potential to decrease the prevalence of harmful plastics in our ecosystems. It is vital to ensure that replacements to conventional plastic is not more damaging than the plastic itself.
• Introduce the widespread use of filtration bags when washing synthetic clothes (e.g. Guppyfriend washing bags).
• Encourage brands to take responsibility for their plastic pollution at all stages of industry, from banning microbeads, to having consumers report litter (e.g. via the Plastic Patrol app).

TL;DR

Microplastics are everywhere, from rain to our drinking water, to the Arctic to the Mariana Trench.

Microplastics can break down into nano plastics, even smaller microscopic particles that can have differing impacts in lots of different ways.

There is not enough evidence to suggest that microplastics lead to negative health outcomes in people, but more research needs to be done in this area. Health impacts are likely to vary between countries depending on their treatment systems.

Improving sewage and water-treatment systems in LEDCs will likely have far-reaching positive effects, far beyond simply reducing microplastic exposure, and should be a priority where possible.

The real issues with microplastics lie in their effect on the environment, as they have been shown to be harmful to animal life at every stage of their degradation.

As with all environmental issues, behavioural change is all well and good, but what is really needed is system change that holds corporations accountable for their disastrous impact on the environment.

While the impacts are not fully understood, the ubiquity and prevalence of microplastics will likely already be causing issues to the environment and potentially our health too. We need more research to see where and how.

Thanks to Hattie for helping me research this huge topic! For more sustainability content, go and follow her on Instagram.