Fibres from wet wipes can get into fertilisers if they are flushed down the toilet
Linda Kennedy/Alamy
Natural fibres that are increasingly being used in wet wipes may actually do more harm to the environment than the synthetic ones they are designed to replace.
Viscose and lyocell, which are made from cellulose in wood, are commonly used in wet wipes and clothing in place of fibres such as polyester, which is primarily a byproduct of fossil fuels.
“They are in high street stores, so you can pick them up in your ethical conscience consumer section of fast fashion stores,” says Winnie Courtene-Jones at Bangor University in the UK.
But there is uncertainty about whether they are really better than the materials they replace. “There’s a bit of a knee-jerk reaction to move away from fossil fuel-based traditional, conventional plastics and substitute those with alternatives, and there hasn’t been much testing of those other materials,” says Courtene-Jones.
To learn more, she and her colleagues tested the impact of viscose, lyocell and polyester on soil and some of the animals that live in it. Wet wipes often make their way into wastewater treatment plants, along with microfibres that come off clothes in washing machines. They are then inadvertently spread on soil via the sludge from these plants that is used as fertiliser.
The team exposed a type of earthworm (Eisenia fetida) to different concentrations of viscose, lyocell and polyester in soil. Around 30 per cent of those exposed to high levels of polyester died after 72 hours – compared with nearly 60 per cent of those exposed to lyocell and 80 per cent of those exposed to viscose.
When the researchers tested lower concentrations that more commonly occur in the real world, they found that the worms exposed to viscose or lyocell reproduced less than those exposed to polyester. Why this occurs is unclear, but any fibrous material could be toxic to earthworms, regardless of its make up.
“Bio-based fibres may [be] better at production time, because they’re not based on fossil fuels, but there’s no clear vision on whether they’re better at degradation time,” says Caroline Gauchotte-Lindsay at the University of Glasgow in the UK. “They have a place, because we still need to replace the fossil fuel industry, but it’s important to know the message isn’t that they’re better once they’re in the environment.”
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