By Petra Dreiser

You may have used one today to rid your countertop of a pesky spill or a shopping cart handle of dubious stickiness: the omnipresent wet wipe that conveniently helps us clean and sanitize soiled surfaces and skin. Yet because some labels do not clearly indicate how consumers should dispose of them, these small cloths often end up flushed down the toilet—and then released by sewage plants into waterways.

In their “Lifecycle of a Wipe: Determining Contamination, Fate, and Transformation of Wet Wipe Pollution in the Environment,” published in ACS ES&T Water, EEB’s Simran Hansra, Jacob Haney, and Chelsea Rochman report that some of these wipes degrade and break down into plastic fibers, or microplastics, that can prove harmful to 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 Hansra, the leader of the study.

A staple in restaurants that serve messy food like barbecue, wet wipes initially came onto the market in the late 1950s to remove cosmetics. Over the years, companies expanded the applications of these small, damp cloths, including as a substitution for traditional toilet paper.

Once someone has flushed the material down the toilet, it usually ends up in treatment plants, where it can clog pipes and require expensive repairs. Wet wipes may also move into waterways when combined sewage overflows release their contents after storms.

Not all wipes are created equal, of course: some are made of cellulose, which breaks down rapidly in the environment, but others consist of plastics that might degrade into more stable, and therefore potentially pernicious, microplastic fibers. To better understand the environmental impact of these disposable cloths, Hansra, Haney, and 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. In their latest paper, they note that wet wipes constituted the second-most-abundant manufactured litter type (behind plastic bags) in the river samples, making up about a quarter of the collected garbage. Of the wipes analyzed, 99 per cent were plastic: 51 per cent were made of polypropylene, 48 per cent of polyester, while the remainder consisted of other polymers, including cotton. The three scientists calculated that about 280 kilograms of wipes—about the weight of a male grizzly bear—were floating in the river at the time they sampled.

Wet wipes constituted the second-most-abundant manufactured litter type (behind plastic bags) in the river samples.

To gain insight into why people flushed wipes in the first place, 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). Only some labels (48) 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, suggesting that plastic-based wet wipes released into the environment could produce microplastics.

For all their convenience, then, wet wipes, Hansra, Haney, and Rochman’s study suggests, warrant a closer second look when it comes to their disposal.