Keeping Microplastic out of the San Francisco Bay
Looking at the San Francisco Bay, you’d never know it’s dotted with tiny pieces of plastic. But new research shows that, like other waters across the United States, the Bay is contaminated with billions of plastic beads, particles, and fibers, all five millimeters or smaller. This microplastic threatens fish and may also threaten people who eat them.
“We can’t recover it once it’s into our watersheds and oceans,” said Stiv Wilson, campaign director at The Story of Stuff, a nonprofit in Berkeley. “People are focused on plastic bags but the small stuff is more dangerous. We need to broaden the dialog.”
Wilson’s recent focus has been microbeads, the teeny abrasive spheres in toothpaste, facial scrubs, and other personal care products. When we rinse our mouths and faces, microbeads go down the drain and into waterways, where fish mistake them for food. “They look like fish eggs, which are a staple of fish,” Wilson said. Microbeads also end up in the plankton that fish and other aquatic animals eat, as well as in corals and shellfish, which filter water for microscopic foods. “It’s like putting uncooked spaghetti down the throats of filter feeders,” he said.
Eating seafood stuffed with plastic may also be a health risk to people. Toxicants like flame retardants and PCBs (polychlorinated biphenyls) stick to plastic, and microplastics can concentrate and transport these pollutants. In a 2015 study, researchers at UC Davis and the Bodega Marine Laboratory in Sonoma County found plastic debris and fibers in a quarter of the fish sold for human consumption in Half Moon Bay.
San Francisco Estuary Institute scientist Rebecca Sutton expected to find microplastics in the Bay. But she didn’t expect to find so many. “It caught me by surprise how high they were compared to waters in other large urban areas,” she said. Her research, published in September, showed that the South Bay has one million pieces of microplastic floating on top of each square kilometer — nearly 10 times more than in Lake Erie.
“The Bay can be a trap for pollutants,” she said. “Water sits here due to the geography.” The only way for water to get out is through the Golden Gate, and this strait is so narrow that it limits turnover.
As a first step in keeping microplastic out of our waters, Wilson helped enact a ban — Assembly Bill 888 — on microbeads in California. While we are not the first state to outlaw microbeads in personal care products, our ban goes further than others. “Companies can’t use plastics claimed to be biodegradable,” he said, explaining that such assertions are unproven. “It’s the toughest ban in the nation.” AB 888 went into effect in October and gives manufacturers until 2020 to phase out microbeads. Natural replacements offer a range of abrasiveness and include beeswax, nuts, seeds, shells, and even sand.
Sutton plans to track the impact of the ban by monitoring microbeads in the Bay, which enter via wastewater treatment plants. In a 2015 study, researchers at UC Berkeley and UC Davis estimated that the United States alone dumps 8 trillion microbeads into aquatic habitats every day.
But microbeads are not the worst problem when it comes to microplastics. Much of the microplastic Sutton found in the Bay was irregular particles, which probably come from big pieces of styrofoam and other plastics that break down over time. “They’re fragmented by wear and tear, and sunlight,” she said. The resulting particles probably enter the Bay in stormwater. So, Sutton plans to monitor creeks and other drainages to the Bay for microplastics, which will help us identify and clean up the sources.
She also found that the Bay is full of little plastic fibers, especially near wastewater treatment plants. The most likely source is our clothes. Fleece is made of polyester, for example, and stretch fabrics get their elasticity from spandex. When we wash a load of clothes that contain synthetic materials, they release microplastic fibers into the water. A single synthetic garment can shed more than 1,900 of these minute fibers, according to a 2011 study led by Mark Browne, an ecologist at UC Santa Barbara.
The rinse cycle sends microplastic fibers that detach from our clothes down the drain, and our wastewater treatment systems are not equipped to filter them out. When microplastic fibers get into waterways, they spread widely. Browne found them on beaches all over the world. “It’s a much trickier issue than microbeads,” Sutton said. “We don’t know what would be effective for controlling them.”
Wilson is up for the challenge. “We’re mounting a microplastic fiber campaign in the spring,” he said. Banning synthetic textiles is not the answer, he said, because many are made of recycled plastic and that’s a good thing. And filtering rinse water from washing machines is tricky because they clog easily, while updating wastewater treatment plants would be “incredibly expensive.” One option is for textile manufacturers to pay into a fund to reduce microplastic fibers. “That would be the most elegant solution,” he said.
While resolving this issue is a long way off, we can start cutting our microplastic fiber footprints right away. You don’t even have to give up fleece. Rather, Wilson recommends wearing natural fiber clothing against your skin and reserving synthetics for outerwear. That way the clothes we wash most often won’t add to the problem. Once microplastics get into our environment, there’s no realistic way to clean them up, so they’ll be there indefinitely. As the saying goes, plastic is forever.
Robin Meadows covers water for the Monitor.