Millions of tiny pieces of plastic, each less than five millimeters wide, are flowing into San Francisco Bay each day. This minute debris—known as microplastic—is a growing environmental concern for water bodies worldwide as it evades filtration and mimics food consumed by wildlife.

Now, a recent study found that San Francisco Bay has higher concentration of microplastic pollution than the handful of other major U.S. water bodies that have been studied, including the Great Lakes and Chesapeake Bay.

Now, a recent study found that San Francisco Bay has higher concentration of microplastic pollution than the handful of other major U.S. water bodies that have been studied, including the Great Lakes and Chesapeake Bay.