Right now, plastics are wreaking havoc on the environment. While plastics have been very useful, they are also quite tough, and instead of breaking down naturally in the environment, they break up into tinier bits that have worked their way into all kinds of places, including water, plants, and the human body. Materials that are made from biological stuff are thought to offer a safer and more environmentally friendly option to plastics. But a new study has suggested that bio-based microfibers may be as harmful or even more dangerous than the plastics they are meant to replace. The findings have been reported in Environmental Science and Technology.
In this study, the researchers compared bio-based microfibers called viscose and lyocell that are found in wet wipes, menstrual products, and clothing to polyester fibers that are used in similar applications.
Earthworms were exposed to high levels these fibers, which can end up in the environment through laundry cycles or sewage systems. The work showed that 30 percent of earthworms died within 72 hours of being exposed to polyester, while 60 percent of worms died in the same time frame after exposure to lyocell, and 80 percent of worms perished after viscose exposure.
In another test, earthworms were housed in various soils that contained different concentrations of each of the fibers. The earthworms in viscose-contaminated soil showed decreased reproduction compared to the worms in polyester-contaminated soil. In lyocell-contaminated soil, earthworms grew less and burrowed into the soil more compared to earthworms in soils containing viscose or polyester.
The researchers noted that these findings emphasize the challenges in plastic reduction, and the crucial need to test materials prior to their use in manufacturing or sale in the marketplace.
"Over 320,000 tons of bio-based and biodegradable fibers were produced globally in 2022 and research shows that substantial quantities of that will end up in the environment. However, evidence of their ecological impacts has been lacking," noted first study author Dr. Winnie Courtene-Jones, who is now a Lecturer in Marine Pollution at Bangor University.
"Our study has shown that bio-based fibers have a range of adverse effects on earthworms—animals which are critical to the functioning of the environment. It highlights the importance of gathering further evidence before alternatives to conventional plastics are made available even more widely."
These conclusions follow previous work that showed that materials that are used in biodegradable teabags can impair earthworm reproduction and increase earthworm mortality by as much as 15 percent.
"I firmly believe it is possible to tackle the plastic pollution crisis, but independent scientific evidence will be critical in helping us avoid unintended consequences as we look for solutions," added senior study author Professor Richard Thompson OBE FRS, Head of the International Marine Litter Research Unit at the University of Plymouth.
Sources: University of Plymouth, Environmental Science & Technology
