Could bacteria and bioplastics fight microplastic pollution?
Microplastics are everywhere, and they harm the environment and our health.
What’s at Stake:
Plastic recycling is failing. The EPA found that fewer than 10% of all plastics are recovered from waste streams and recycled. Water bottles are a particular problem. Americans use a staggering 1,500 plastic bottles of water every second. Worse, we throw out about 80% of the bottles we use. A 2020 study found that the United States generated far more plastic waste than any other country. And the amount entering the oceans has increased five-fold since 2010.
Plastic bottles and other discarded plastic products disintegrate into microplastics, which go everywhere: the air, the oceans, drinking water, and food. Researchers have even found microplastics in the placentas of fetuses. Plastic bottles release PFAS, carcinogenic “forever chemicals” that do not break down in the environment. In addition to cancer, PFAS are linked to liver and thyroid damage and pregnancy risks, among other health problems. Don’t think you’re exempt: PFAS have been found in the blood of over 98 percent of Americans. See this 2021 story in The Guardian by Adrienne Matei.
Plastics also harm marine animals that ingest them. Microbes build up on plastic waste in the ocean, making them smell tasty to turtles and fish. Scientists can only track about one percent of the plastic released into the ocean, where it is found on the water’s surface and in the guts of marine animals. The rest washes ashore, is eaten, or settles to the ocean floor.
See this 2021 story in Orion by Meera Subramanian.
Bottles aren’t the only problem. You may think of tires as natural “rubber,” but tires have a high plastic content. About 280 million tires are discarded each year by American motorists. The Department of Transportation estimates that as many as 2 to 3 billion discarded tires may have accumulated nationwide. Unfortunately, tires are a leading contributor to microplastics in the environment. Worldwide, 100,000 metric tons of microplastics are shed from tires annually as they roll down the road. These microplastics are transported through the air and fall into the ocean. Airborne tire microplastics reaching the sea each year weigh the same as about 11 million tires. And that doesn’t include the microplastics released by tires degrading in dumps. See this 2020 story in The Conversation by Claire Gwinett.
An international study in Science Magazine predicted that growth in plastic waste was on course to overwhelm all existing efforts to mitigate plastic pollution. But what about new efforts?
German researchers discovered bacteria that break down plastic by eating it. The microbes, called pseudomonas bacteria, target polyurethane. This is great news because polyurethane is tough to recycle. However, years of research and development are needed before the bacteria can be safely harnessed at a large scale. See this 2020 story in EcoWatch by Jordan Davidson.
German scientists recently developed a new kind of bioplastic that functions similarly to the plastic used in drinking bottles and is easier to recycle. Researchers transformed oils derived from plants or microalgae into strong polymers that break down under common recycling conditions. The hope is that more bottles will be recycled.
Plastic is considered biodegradable “only if it breaks down into fragments that can be completely consumed by microorganisms in the disposal environment within a defined time period,” according to this 2019 story in Knowable Magazine by Marcus Woo. And we shouldn’t just throw biodegradable plastics anywhere; many of them break down only in controlled conditions in industrial composting centers.
Since tires are a major source of microplastic pollution in the air and water, it’s essential to develop bioplastic alternatives that are less harmful to the environment and human health. In 2022, Goodyear announced a demonstration tire that is 70% bioplastic. Some of the ingredients in the tires include soybean oil, silica from rice husks, and recycled polyester. There is more work ahead to develop more environmentally friendly tires.
Convert Food Waste into Bioplastics
A 2020 study from India found that it was possible to convert waste from food production into biopolymers, the building blocks of plastics. These included: the shells of shrimp, prawns, and crabs; dairy waste such as cheese and whey; potato waste; sugarcane byproducts; fish waste; poultry waste; cooking oils; fruit and vegetable waste; spent coffee grounds; and grain byproducts. The resulting bioplastics would contain fewer toxic chemicals. They would also reduce methane and other greenhouse gases from food waste in landfills.
Reduce, Reuse, Recycle
Consumers can have a significant impact on plastic waste. We can reduce the amount of plastic we buy, avoiding plastic water bottles and produce in plastic clamshell boxes. We can reuse plastic items we already have rather than throw them away. And we can recycle correctly. It’s important to place only appropriate items in the recycling bin. Otherwise, we reduce our municipalities’ overall ability to recycle. Meanwhile, scientists are working on high-tech solutions.