How does plastic get into the oceans?

How does plastic get into our oceans?

It’s estimated that a third of all plastic waste ends up in nature, in some form. This includes the oceans. 

We’re always hearing about plastic in our oceans—but how does it get there? That’s the question I’m aiming to answer today.

It enters as fishing gear 

Approximately 10% of plastic in the oceans originates from fishing gear, such as nets.

Many sources have cited 46% as the percentage of fishing nets discarded or lost in the ocean. However, that statistic comes from a measurement of the “Great Pacific Garbage Patch”; which cannot be generalized to the rest of the ocean.

This isn’t to discount the massive impact of fishing gear in our oceans—nets are still certainly much more destructive than plastic straws, for example.

I’d like to thank @greenmarinescientist for helping me find and understand these sources.

It enters as microplastic (tiny pieces of plastic)

For example:

  • washed off of our clothing and other laundry
  • as an ingredient in skincare products, like toothpaste and exfoliants (microbeads) 
  • wear and tear of vehicle tires (an estimated 5-10% of ocean plastic is estimated to come from tires)
  • plastic that have been broken down from larger pieces over time (eventually all plastic will break down into smaller parts)

According to a 2018 study, 30 billion particles of microplastic are released into the ocean each year (typically from laundry)–and that’s just from Vancouver. Plus, this is after treatment centres filter out 1.8 trillion plastic particles in waste water.

It is added intentionally

Sad but true. This can include:

  • dumping in areas around the world without waste collection services or waste management infrastructure, such as proper landfills/recycling 
  • illegal dumping by trash haulers or companies
  • illegal dumping at sea by cruise ships

It “escapes” unintentionally

There are countless ways this happens; for example:

  • trash left on a beach
  • litter that falls into a gutter
  • plastic that falls off a car or a recycling truck
  • litter or trash from garbage bins carried off by birds or other animals
  • bags and other lightweight plastics blown away from landfill sites and illegal dumps

Basically, once our plastic leaves our hands, even if we have the best of intentions, there’s no guarantee that it gets to the right place.

But wait—it’s not just the ocean

You don’t need to have an ocean nearby for your plastic to end up in the sea—plastic can travel far and wide, such as by wildlife and through other waterways.

Plus, plastic—including microplastic—is prevalent in freshwater sources, such as lakes and rivers. Of course, this also includes drinking water sources. 

In a new study, researchers estimated that we consume upwards of 5 grams of plastic a week—that’s like eating a credit card every week.


Esther A. Gies, Jessica L. LeNoble, Marie Noël, Anahita Etemadifar, Farida Bishay, Eric R. Hall, Peter S. Ross. (2018). Retention of microplastics in a major secondary wastewater treatment plant in Vancouver, Canada. Marine Pollution Bulletin.

Kole, P. J., Löhr, A. J., Van Belleghem, F., & Ragas, A. (2017). Wear and Tear of Tyres: A Stealthy Source of Microplastics in the Environment. International journal of environmental research and public health, 14(10), 1265. 

Lebreton, Slat, Ferrari, Sainte-Rose, Aitken, Marthouse, Hajbane, Cunsolo, Schwarz, Levivier, Noble, Debeljak, Maral, Schoeneich-Argent, Brambini, Reisser. (2018). Evidence that the Great Pacific Garbage Patch is rapidly accumulating plastic. Scientific Reports,  8 (1) DOI: 

Matousek, Mark. (2019). Carnival got hit with a $20 million fine after dumping garbage into the ocean, but it’s not the only cruise line guilty of trashing the sea, an expert says. Business Insider.

National Ocean Service. National Oceanic and Atmospheric Administration. Us Department of Commerce. (2018). What are microplastics?

Ocean Conservancy; McKinsey Center for Business and Environment. (2015). Stemming the Tide: Land-based strategies for a plastic-free ocean. 

United Nations Environment Programme. (2009). Abandoned, lost, or otherwise discarded fishing gear.

University of Newcastle Australia; Dalberg; & WWF International. (2019). No plastic in nature: Assessing plastic ingestion from nature to people. [Consumer article available at]

WWF UK. (2019). How does plastic end up in the oceans? 


2 responses to “How does plastic get into the oceans?”

  1. […] There are many ways someone can be an environmentalist, and straws are just one tiny example. For example, they make up 0.025% of ocean plastic. Fishing gear, meanwhile, makes up 10%. […]

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