What Are Microplastics, Anyway?

Microplastics are a growing environmental concern — from the 2015 ban on microbeads to the more recent discussions on microfibers — but how many of us know what microplastics really are?

Microplastics are pieces of plastic that are less than five millimeters long. We’ve begun to pay closer attention to these small plastic bits only recently, but they actually aren’t all that new. One common form of microplastics, microbeads, first appeared in personal care products fifty years ago.

The reason these tiny plastics have become so popular recently is that they’ve been turning up in our water — in huge quantities.

Because of microplastics, scientists have begun calling our oceans “plastic soup.” A 2015 study estimated the number of plastic particles in our oceans ranged from 15 to 51 trillion pieces, weighing between 93,000 and 236,000 metric tons. But how do all the tiny plastics get there?

Large plastic debris that ends up in the ocean breaks down quickly in the water and sunlight. Because of this, over 90 percent of the plastic in our ocean is less than 10 millimeters long. The problem with small plastics is that — to our knowledge — they will never biodegrade. When they’re eaten by fish, they aren’t fully digested. Instead, they simply accumulate as smaller and smaller pieces that become more difficult to deal with.

About 700 different species consume microplastics, and what happens to animals that eat them isn’t fully known. So far, microplastics have been shown to decrease the overall health of marine worms, and they have also been shown to transfer pollutants to animals that consume them. Given what we know about the health hazards of plastics in general, it seems likely that other negative effects will surface as research continues.

Microplastics are also small enough to work their way into our tap water, because they slip easily through our water filters. According to a recent study, microplastics were found in over 94 percent of U.S. water samples. Microfibers — tiny strands of synthetic fabric — are another common source of microplastics. These work their way into the water supply each time we run our polyester and nylon clothing through a washing machine.

To combat the growing issue of microplastics, the U.S. passed the Microbead-Free Waters Act in 2015, banning plastic microbeads from cosmetics and other personal care products such as toothpaste and exfoliants. Researchers are currently hard at work to build better water filters for our water supply, and to find new ways to remove plastic trash from our oceans. The best thing for the rest of us to do is limit our use of plastic, especially single-use plastics and synthetic clothing.

Learn more about how to reduce plastic waste.