Microbeads are the tiny plastic particles that are often found in personal care products, where they are utilized for exfoliant purposes. Usually measuring around 1 millimeter or less in diameter, microbeads resemble nothing quite so much as plastic sand, yet their synthetic composition prevents these tiny particles from breaking down when introduced into the natural ecosystem. Microbeads may go down your drain at the end of your shower or after you've brushed your teeth, but they most certainly do not go away.
The Great Lakes represent a "Patient Zero" situation for plastic microbead infection. A recent study, conducted in 2014 by the 5 Gyres Institute, found that an astonishing 43,000 microplastic particles were present in every square kilometer of tested lake water. When samples were taken in proximity to major cities, that number jumped as high as 466,000. Billions of microbeads are making their way into rivers and lakes each day across the country, and they quite simply don't degrade, meaning they slowly accrue over time.
Even if the use of microbeads is curbed and they are replaced with safer, biodegradable alternatives, the reality is that the problem won't completely go away overnight. Our waterways are already heavily contaminated with microplastics, and the amount of time required for these particulates to break down is simply too long, meaning they will continue to be a danger to marine life until cleaned up. By corollary, this means they will also continue to negatively impact human health as well. Banning the manufacture and use of microplastics is a massive step in the right direction, but it may likely be years before plastic microbeads are no longer an issue facing the sustainability community.