Scientists have tested, for the first time, how biodegradable wet wipes break down when flushed rather than composted discovering that most wipes remain after five weeks – a finding the research team say challenges the marketing of these products.
Researchers from Cardiff University's Schools of Biosciences, Chemistry and Engineering tested two widely-available brands of wipes labelled as 'biodegradable' in ten urban rivers and streams in Cardiff, UK
For five weeks, the team tracked the degradation of the wet wipes in these locations by testing their tensile strength loss, and recording environmental factors such as microbial biomass, water chemistry, temperature, and river-level fluctuations.
Dr Thomas Allison, Postdoctoral Research Fellow at the University's School of Biosciences and its Water Research Institute, said: "The use and disposal of wet wipes have been problematic, because when flushed, they can accumulate in rivers and freshwater systems. Eco-conscious consumers might try to make more eco-friendly choices by opting from wet wipe products marketed to be more eco-friendly and biodegradable."
Whilst these products are marketed as biodegradable, their behaviour in freshwater systems has been largely untested. We wanted to test, for the first time, wet wipes marketed as biodegradable.
The two brands tested were cellulose-based and the team found that the wet wipes which contained more natural cellulose decayed more than twice as fast as those dominated by regenerated cellulose.
Wet wipe Brand A, which contained more natural cellulose, degraded around 6.7% per day. Brand B, containing more regenerated cellulose, degraded around 3.1% per day.
They found that the real-world urban river environment accelerated degradation compared to previous lab testing. This is likely due to the higher microbial activity and dynamic conditions – such as temperature and river level fluctuations - in rivers.
The study found that despite early decay, most wipes persisted after five weeks. The research team believe that one of the reasons for this persistence could be due to the large amount of river debris coating these materials over time which may act as a protective layer.
Eco-labels and biodegradability standards need urgent reform to better reflect real-world conditions. Clearer disposal guidance is an essential part of preventing wipe flushing and to reduce pollution.
"The persistence of these wet wipes that have been marketed as biodegradable challenges the credibility of their marketing.
"Many of the claims around their biodegradability are based on lab-based testing and do not reflect the reality of how they actually perform in freshwater environments. For the first time, we've analysed these wipes in-situ – in the rivers and streams where they end up if flushed away- and found a different story.
"Our findings suggest there is a need to reform eco-labels, biodegradability definitions and degradation testing standards for wet wipe products - as well as greater scrutiny of plastic-free alternative products and their environmental fates," added Dr Allison.
The research, Degradation of cellulose-based wet wipes marketed as 'biodegradable' in their receiving urban rivers , was published in Environmental Pollution.
