How and Why Microplastics Invade Our Everyday Lives

Organizations like the Ocean Cleanup use nets (above) to capture large pieces of trash, but microplastics often slip through. Data from a 2016 study (left) found that fibers made up as much as 71 percent of microplastics that flow into the Great Lakes.

- By Kim Hickok

The abundance of single-use plastic items such as water bottles, grocery bags, and packaging materials has soared since the 1950s. These objects break down into microplastics, or tiny bits of plastic less than 5 millimeters long (less than half the width of your pinky fingernail), which are now ubiquitous.

No one knows exactly how much microplastic has made it into the environment, but in 2021, an international team of multidisciplinary scientists estimated that there were 24.4 trillion pieces of microplastics in the world's upper oceans alone, or the equivalent of roughly 30 billion plastic water bottles.

Because of their minute size, microplastics aren't easy to track. For many years, researchers assumed these tiny bits of trash entered rivers, where they were carried downstream to the ocean in a relatively short amount of time. But that's not actually the case. According to a new study published in Science Advances, it's estimated that microplastics may remain in rivers for more than 300 years before entering the ocean. This means the microplastics in rivers have much greater potential to cause harm to humans and the environment than scientists previously thought.