Plastic poser
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 bodies of water in the United States, according to a 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 non- profit research centre.
Not only does the plastic contaminate the bay and wildlife, experts say, it is 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, researchers dragged tight- meshed nets along the surface of the water in nine areas of the bay. They found on average one million pieces of tiny plastic per square kilometre at the water’s surface or a few inches below it in the South Bay. Further north, off Oakland and San Francisco, they found 310,000 pieces per square kilometre.
The researchers also captured nine fish and 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.
Sutton said more research is needed to measure the health effects, and also to pinpoint exactly how much plastic is getting into the bay and from what sources. The researchers also sampled the treated wastewater coming from some of the bay’s largest sewage treatment plants. They found tiny plastic pieces flowing through all the plants – regardless of how advanced the technology – because the facilities were designed to treat sewage, not filter tiny plastic debris. And that is only part of the problem; plastic also flows in from storm drains, creeks, rivers and illegal dumping.
Retrofitting all the sewage treatment plants with fine membranes to catch the particles, many of which are like confetti, would cost hundreds of millions of dollars, said David Williams, executive director of Bay Area Clean Water Agencies, an association of the sewage treatment plants. “The micro- particles are of concern to us,” he said. “We’ve known for some time that there are things that our plants just don’t remove.”
Williams said in the short term, the solution is for people to avoid putting any type of trash, particularly plastic, into toilets. He said consumers also should not buy cosmetics, facial scrubs or toothpastes containing plastic microbeads.
Meanwhile, California lawmakers recently passed a bill that would ban plastic microbeads in cosmetics and personal care products sold in the state from January, 2020. – San Jose Mercury News/ Tribune News Service