Paul Rogers, SAN JOSE MERCURY NEWS
San Francisco Bay is contaminated with widespread pollution from billions of tiny pieces of plastic in greater concentrations than the Great Lakes, Chesapeake Bay and other major U.S. bodies of water, according to a groundbreaking new study.
At least 3.9 million pieces of plastic pour into the bay every day from eight large sewage treatment plants — a relentless torrent of litter that ranges from tiny “microbeads” found in cosmetics, facial scrubs and toothpastes, to bits of synthetic fabric from fleece jackets, pants and other clothes, which break down as they are washed.
“We’re concerned about these high levels. This was unexpected,” said Rebecca Sutton, a senior scientist at the San Francisco Estuary Institute, a nonprofit research center based in Richmond.
Microplastic poses a growing concern in oceans and other aquatic habitat. Not only does the plastic contaminate the bay and wildlife, experts say, it is also working its way up the food chain, binding to chemicals in the water and posing a potential health risk to people eating fish caught in the bay.
In the study, the first of its kind to broadly document pollution from “microplastic” in the bay, researchers dragged tight-meshed nets along the surface of the water in nine areas of the bay, from Oakland and Treasure Island to locations near San Jose. They found on average 1 million pieces of tiny plastic per square kilometer — an area of about 250 acres — at the water’s surface or a few inches below it in the South Bay, a concentration nine times higher than levels of similar plastics found in Lake Erie.
Further north, off Oakland and San Francisco, they found 310,000 pieces per square kilometer, still double the highest levels in Chesapeake Bay and triple the levels in Lake Erie, the most polluted of the Great Lakes.
Sutton, a lead author of the study who has a doctorate in environmental chemistry from UC Berkeley, said that researchers also accidentally captured nine small fish while taking their water samples. Inside each fish they found an average of six pieces of plastic.
Other scientific studies have found that tiny pieces of plastic in the world’s oceans and water bodies, sometimes so dense that they outnumber plankton, can absorb contaminants such as pesticides and PCBs, which accumulate in fish when they mistake the plastic for food. The small fish are then eaten by larger fish. And people who eat the affected fish can be exposed to the chemicals when they consume the plastic.