Wet wipes conveniently clean and sanitize soiled surfaces and skin. Because some labels do not clearly indicate how consumers should dispose of them, these small cloths often are flushed down the toilet and released by sewage plants into waterways. Now, researchers report in ACS ES&T Water that some of these wipes break down into plastic fibers, or microplastics, that could harm aquatic life.
“Plastic wet wipes are an underrepresented type of single-use plastic and are a source of macro- and microplastic pollution in our water,” says Simran Hansra, the leader of the study.
A staple in restaurants that serve messy food like barbecue, wet wipes were initially invented in the late 1950s to remove cosmetics. Over the years, companies expanded the applications of these small, damp cloths to include their substitution for traditional toilet paper. After the material is flushed, it usually ends up in treatment plants, which can clog pipes and require expensive repairs. Wet wipes can also move into waterways when combined sewage overflows release their contents after storms. Some wipes are made of cellulose, which breaks down rapidly in the environment, but others are made from plastics that could degrade into more stable microplastic fibers that may harm aquatic wildlife. To better understand the environmental impact of these disposable cloths, Hansra, Jacob Haney and Chelsea Rochman investigated how they break down in waterways.
The researchers sampled the Don River in Toronto, Canada, for plastic pollution, including microplastics, in 2022 and shared their findings in a previous study. Now, they report that wet wipes were the second most abundant manufactured litter type behind plastic bags in the river samples, making up about a quarter of the collected litter. Of the wipes analyzed, 99% were plastic: 51% were polypropylene, 48% were polyester and the remainder were other polymers, including cotton. They calculated that about 620 pounds (280 kilograms; about the weight of a male grizzly bear) of wipes were floating in the river at the time they sampled.
To gain insight into why wipes were being flushed, the team carefully examined labels on boxes of commercially available wipes from popular stores in Toronto and a popular online retailer. Only seven out of 72 product labels stated the material they were made of (e.g., cellulose or synthetic polymers), and 48 of the labels included disposal instructions, such as “flushable” or “do not flush.” Because so many wipes were found in the Don River, the researchers conclude that many consumers are flushing wipes that shouldn’t be sent down the toilet.
In laboratory experiments, the team assessed how commercially available wipes degrade in simulated environmental conditions. As expected, cellulose wipes labeled as “flushable” broke down the fastest, losing the most mass over six weeks, followed by polypropylene and then polyester wipes. Both sun and water treatment increased mass loss compared with dry, dark conditions. All the wipes shed microscopic fibers during the experiments, which suggests that plastic-based wet wipes released into the environment could produce microplastics.
