Microplastics Pollution Is Everywhere. Is It Harmful?

Microplastics are everywhere. They've made their way into our food and water supply. There's no doubt we're ingesting them. Are they harmful?

Sabrina Stierwalt, PhD
6-minute read
Episode #338

Microplastics pollution is everywhere. From your toothbrush and your drinking glass to the packaging on your food and the protective case on your phone, think about all of the times in just a day that you use plastic. Since we began mass producing plastics in the 1940s, somewhere around 8.3 billion tons of plastic has been produced and, as of an estimate done in 2015, 6.3 billion tons—so, near 80%—of that has been tossed into landfills. An astonishing 20,000 plastic drink bottles are bought every single second with less than half of those collected for any type of recycling. 

According to the National Oceanic and Atmospheric Administration, it takes a plastic bottle 450 years to biodegrade. That’s about the same amount of time it would take for a synthetic diaper to biodegrade. That means just about every water bottle that was ever produced or used is still hanging around. And an estimated 8 million metric tons of plastic—an amount as heavy as 90 aircraft carriers—makes its way into the ocean every year.

An estimated 8 million metric tons of plastic—an amount as heavy as 90 aircraft carriers—makes its way into the ocean every year.

Microplastics definition

Any piece of plastic less than 5 millimeters in size is considered a microplastic. Microplastics can come from a few sources, including those small beads found in some soaps and lotions that are usually sold as good for exfoliation. Microplastics also include microfibers that are shed by the millions from synthetic clothing like fleece, acrylic, and polyester with each wash. Secondary microplastics are the smaller pieces of once larger plastic items, including anything from toys to furniture. 

Where is microplastic waste found?

Microplastics are found just about everywhere. And that’s not an exaggeration. They’ve been found on the coast of Spain, in the Yangtze river in China, in the Great Australian Bight, the Mariana Trench, and in lakes and rivers across the United Kingdom

According to the US Geological Survey, in the United States, microplastics are found in 12% of freshwater fish in the United States. They are also found at a rate of 112,000 particles for every square mile of water in the Great Lakes, and 1,285 particles for every square foot of river sediment. 

It’s starting to look like no region is remote enough to escape the plastic pollution invasion we have created.

A UK study investigated the digestive tracts of 50 marine animals across ten different species and found microplastics in every single one of them, although in low enough numbers that the authors suggest the particles might not stay in the gut for long. 

It’s starting to look like no region is remote enough to escape the plastic pollution invasion we have created. Scientists recently studied the secluded wilderness in the Pyrenees mountain area shared between France and Spain, more than 75 miles to the nearest major city and more than 4 miles to the nearest village. They found 365 microplastic pieces for every square meter of land, which suggests microplastics don’t have to travel via our waterways but can also be airborne. Microplastics have also been found in the Arctic

Are we ingesting microplastics?

It's probably not surprising that microplastics are found in our drinking water. In an investigation commissioned by the Orb Media group, microplastics were found in 83% of the tap water samples tested worldwide. The United States had the highest rate of contamination—94% of water samples, including some taken from Congress buildings in DC, contained microplastics. The next highest rates were observed in Lebanon and India. The lowest rates were found in Germany and France, although those “low” values were still rates of 72%. Microplastics were also found in tap water in Ecuador, Indonesia, and Uganda. 

There's evidence that microplastics are found in bottled water at rates twice as high as in water straight from the tap.

Think you can avoid it by drinking only bottled water? Think again. There's evidence that microplastics are found in bottled water at rates twice as high as in water straight from the tap. Even just drinking beer isn’t safe—there are microplastics there, too. (Note that the original study was essentially a literature review and was criticized for not clearly defining what they were considering as microplastics. The group later commissioned a peer-reviewed version of these results that noted similar results but with an expanded definition of contamination beyond just microplastics to also include any kind of anthropogenic contamination.)

Microplastics are also found in our food supply. One study looked at the amount of microplastics found in fish, shellfish, added sugars, salts, alcohol, tap water, and bottled water, and then estimated how much microplastic we likely consume based on the Dietary Guidelines for Americans. The results varied with age and sex and ranged from an ingestion of 39,000 to 52,000 particles annually from foods that amount to only 15% of the average American’s caloric intake. 

There is no doubt that we are ingesting microplastics. They are found in our food supply, our water supply, and even in our stool, according to analysis of stool samples from volunteers in Europe, Japan, and Russia. The study was small—only eight people—but the scientists found an average of 20 pieces of plastic in every 10 grams of poop, which means we could be excreting close to 1,000 pieces of plastic every day

Are microplastics harmful to our health?

But are microplastics actually harmful? The jury is still out on this, but not due to conflicting results. It's mostly because we haven’t done enough research yet to firmly answer yes or no.

Scientists suspect that, due to their small size, microplastics should be able to enter our bloodstream, our lymphatic systems, and even our livers. Microplastics found in waters off the coast of Singapore were found to host toxic bacteria. Obviously, that doesn’t sound like something I want infiltrating my organs. Microplastics, like the microfibers from our clothing, can also absorb harmful chemicals—like the flame retardants we put on that same clothing—and release them later, perhaps after they’ve wound up in our gut. But some microplastics may be more or less harmful than others. 

Studies of birds have shown that ingesting plastic disrupts iron absorption, stresses the liver, and even goes so far as to reshape parts of the small intestine.

Studies of birds have shown that ingesting plastic disrupts iron absorption, stresses the liver, and even goes so far as to reshape parts of the small intestine. But we don’t yet know how much of these findings are applicable to the human digestive system. 

Hopefully we will see more of these answers soon. The United Kingdom has begun a study of the health impacts of microplastics. The World Health Organization has also launched a study to investigate the level of microplastics in bottled water. 

What can we do about microplastics?

In 2015, President Obama signed the Microbead-Free Waters Act of 2015, which no longer allowed microplastic beads in personal care items like cosmetics and toothpaste. The ban did not cover microplastics found in other places like sunscreens, cleaners, or flushable wipes. Such efforts are a first step toward combating the microplastic problem. 

As individuals, we can cut out single-use and disposable plastics as much as we can. If you, like me, find the idea of trying to avoid plastic very daunting, there are programs to help, like the Marine Conservation Society’s Plastic Challenge. We can also volunteer to pick up larger plastic litter in our communities so it doesn’t erode into smaller pieces and end up as microplastics in our air, water, and food.

And there may also be hope for the microplastics that have already found their way into our waters. Just last week, Irish teenager Fionn Ferreira won the annual Google Science Fair for his proposed method for removing microplastics from water. Ferreira added both a plastic-type solution and ferrofluids—liquids with magnetic properties—like oil and magnetite to water. He found that the plastic solution would latch onto the ferrofluids and then both could be removed with a magnet.

How are you removing the plastic from your life? 

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Until next time, this is Sabrina Stierwalt with Ask Science’s Quick and Dirty Tips for helping you make sense of science. You can become a fan of Ask Science on Facebook or follow me on Twitter. Listen and subscribe on Apple, Spotify, Google, Stitcher, or wherever you get your podcasts. If you have a question that you’d like to see on a future episode, send me an email at everydayeinstein@quickanddirtytips.com

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About the Author

Sabrina Stierwalt, PhD

Dr Sabrina Stierwalt earned a Ph.D. in Astronomy & Astrophysics from Cornell University and is now a Professor of Physics at Occidental College.