7-TRILLION Tiny Pieces of Plastic Flow Into San Francisco Bay EVERY YEAR

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Grocery bag pileup in California. Photo: Earl S. Cryer/ZUMA Press

A comprehensive three-year study has discovered that 7 trillion tiny pieces of plastic, roughly equal to 1 million pieces each for every citizen in the Bay Area, flow into San Francisco Bay, every single year.

The study discovered that billions of pieces of “microplastic”, defined as particles smaller than 5 millimeters each, pour through the Bay Area’s 40 sewage treatment plants every year, reports the East Bay Times. The particles come from synthetic fibers in clothing, like fleece jackets that shed in washing machines or baby wipes flushed down toilets, and then wash down sewer pipes, pass-through treatment plant filters and empty into bay waters.

“These are pieces smaller than a kernel of popcorn,” said Rebecca Sutton, lead author of the study and a senior scientist at the San Francisco Estuary Institute, a non-profit research center in Richmond. “Many of them are too small to even see. You have to use a microscope. They are tiny little particles and tiny little fibers.”

But that amount is dwarfed by the amount that comes from storm drains, by far the largest source of the particles, by 300x. The drains collect all sorts of plastic litter from roads, such as foam food packaging, residue from car tires, and many other sources, and deposit the debris to creeks and the bay.

plastic, San Francisco, California, pollution
Credit: SFEI

The study, conducted by researchers at the San Francisco Estuary Institute, UC Davis, the University of Toronto and other institutions, was released Wednesday.

The study has also found that all those tiny particles are accumulating in small bay fish, like anchovies. These smaller species are then eaten by larger animals, including big fish, birds, sea lions, and humans. According to an Australian study, the average person in the world ingests 5 grams of plastic every week, about the same amount as in a credit card.

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