Microplastics: A macro issue?

It is a curious situation that the sea, from which life first arose, should now be threatened by the activities of one form of that life. But the sea, though changed in a rather sinister way, will continue to exist: the threat is rather to life itself. Rachel Carson, Marine Biologist


Kaikoura, New Zealand

On the morning of Monday June 8th I didn’t know it was World Oceans Day. I did know it was a public holiday, so I woke up with the languid ease that comes from feeling like you’ve gained a day. Twenty-four hours of unscheduled freedom.  No work and no study, although I could have done either.  Armed instead with my commitment to the illusion of gifted time, I finally found the space to read the articles I’d been meaning to read about for weeks, about microplastics affecting aquatic ecosystems.

I had about four of them, dense scientific articles about these tiny pieces of plastic that are getting under the skin of the ocean.  I settled in with a cup of tea and started to read.

The first I heard about World Oceans Day was a couple of days later.  It’s a relatively new ‘day’, declared in 2008 and recognized by the United Nations as an opportunity to celebrate our connection to the ocean, reflect on our impact on its ecosystems and maybe do something to help.  It was humbling to discover that while I was having a solitary morning reading about oceans, thousands of people around the world were feeling the oceans in their own way.

We all know that the ocean is a big mama who influences our climate, supports life both inside and out and is constantly in motion . . . and I’d heard that she’s been having some troubles. I am not an oceanographer or a scientist, but recently I’ve come to understand that the threats facing the oceans and its inhabitants are the same ones that we face as humans. Which of course, as a selfish human, made me sit up and start asking questions.

This isn’t going to be a treatise on the state of the ocean, but I would like to share a couple of things I found out about microplastics because (another coincidence), the focus of this year’s World Oceans Day was plastic pollution.  Also, earlier this year I got in touch with an organisation based in Montana called Adventurers and Scientists for Conservation. They are doing exciting work connecting research scientists with people who can collect samples for them, sometimes in remote and inhospitable locations where sending a team of field scientists would be complex, expensive or impossible. One of their current projects is around monitoring microplastics in oceans and rivers. It’s a privilege to be collecting some samples for them while I’m here in Tasmania, and to be learning about microplastics at the same time.

Back to microplastics. Here’s what I’ve found out so far: Most of us are familiar with macroplastics: big bits of plastic. 230 million tonnes of the stuff were produced in 2009. It’s a big thing. Plastic bags, milk cartons, beach bananas, fishing wire and nets – plastic debris has been recognized as a threat to river and marine ecosystems for many years. There have been campaigns across Australia to ban plastic shopping bags, promote reusable drink bottles and coffee cups and reduce waste in really positive ways. And there’s Clean Up Australia Day. If we’re doing that here, you can only imagine the amazing things that are happening in Scandinavia, right? Macroplastics are a big issue and we know a fair bit about them.

Microplastics are small, and we still don’t know a whole lot about them.  At the end of last year The Guardian published an article calling microplastics ‘the biggest environmental problem you’ve never heard of’.  Small plastic fragments were first identified in the open ocean the 1970s, but there wasn’t much follow up for about 30 years. The past decade has seen a resurgence in interest and concern about these tiny pieces of plastic. Research into microplastics is so new that it wasn’t until 2008, at the first international conference on microplastics, that they were actually defined.  Microplastics are plastic particles that are 5mm and smaller. So they’re not actually that small. There is still some contention around the definition (some scientists say this is too big), but for now 5mm is the accepted benchmark. There are two main types of microplastics:

  1. Secondary Microplastics: these come from the break down of macroplastics in the ocean and on beaches due to UV light and weathering
  2. Primary microplastics: these come directly from particles of plastic that are already <5mm.

I was kind of shocked to hear where some of these primary microplastics come from. Things like:

  • Chewing gum
  • Cosmetics
  • The exfoliating beads in a lot of those exfoliating face washes
  • Filaments in fleeces and other synthetic fibers that slough off during a wash cycle

Yep, we are chewing, wearing and washing with little bits of plastic. We are surrounded by it. The last one was of particular concern to me because, like a lot of people who spend time in the outdoors, I wear fleece a lot.  Apparently this is one of the major sources of primary microplastic pollution. In 2011, an Australian ecologist researched the microplastics that come from domestic washing machines and approached several outdoor gear manufacturers with his findings. He asked them to partner with him in further research into sustainable textiles and microplastic movement. They declined, one of them quite reasonably saying they they didn’t want to invest in looking for solutions to a problem that isn’t yet fully understood.  And it’s not.


Derwent River, Hobart, Tasmania

Scientists are concerned about microplastic pollution for a few reasons:

One: Animals can eat them. The ugly issue of marine mammals and birds ingesting big plastics isn’t anything new, and it’s horrible. But what happens if animals at the bottom of the food chain are eating plastics too? What impact will that have on the rest of the food chain? Animals that eat plastic might feel full and eat less, missing out on essential nutrition, affecting any number of their systems. They could also choke on oddly shaped or large plastic particles. Another unexpected consequence scientists fear is that some fish, which migrate from shallow to deep water to feed could be prevented from being able to go deep like they need to if they’ve ingested buoyant plastics. All of this action at the bottom of the food chain could impact species all the way to the top.

Two: We like our plastic products to last – it’s better for environment, right? Less waste. But to make plastics more durable we add chemicals called plasticisers. These make the plastic last longer, but eventually the chemicals leach out as the plastics degrade. Ingested by marine animals they could mess with hormones, reproduction and cause cancer. There’s not a whole lot of research into this yet but it doesn’t sound good.

Three: Plastics can absorb metals, chemicals and other pollutants like DDT. This means that when animals ingest them, they’re also taking in the toxins attached to the plastic, and when they move they might take these toxins with them. We don’t know much about this yet either, but it sounds like something that matters.

One of the major challenges with microplastics right now is that there are so many unknowns. We don’t know for sure what eating microplastics does to marine organisms. We don’t know whether they can be passed up the food chain and what happens if they are. We also don’t know much about how microplastics work as transporters of other toxins.  We certainly don’t know what can be done to reduce the concentration of microplastics in the oceans and rivers. I am no scientist, but I know this: this is how science begins. With an observation, a question, a hypothesis and a series of answers that slowly build to an understanding.  So let it continue.


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