Wet wipes, a universally valuable and versatile product, we use them for everything hygiene related. From wiping down tables to wiping our rears, these materials make the lives of many just a little bit cleaner and a little bit easier. But have you ever considered, once you flush them down the loo, what happens to these little sheets?
Hi, I’m Dan, a PhD student at the University of East Anglia. My work involves investigating plastic material alternatives and how they may impact the environment as litter.
We all know plastics aren’t great for nature. They last forever, never truly disappearing but instead breaking into smaller and smaller pieces known as microplastics. They end up in the environment, either being littered, or through wastewater and the atmosphere. Oceans, rivers and lakes are especially vulnerable to microplastics, being clogged with thousands of pieces of plastic every day. One significant culprit are the plastic microfibres that are used in clothing, furniture, and you guessed it, wet wipes.
Now, biodegradable alternatives are becoming more popular, with a push towards the banning of single use plastics by governments such as the EU and UK. Wipes made of semi-synthetic or natural fibres are increasingly popular, such as cotton or rayon, which are believed to rapidly degrade and have little impact on the environment. On the other hand, these materials are often heavily modified in the manufacture process, imbued with hazardous chemicals that could slow their degradation and potentially be toxic to aquatic ecosystems. Importantly, we don’t know if these materials truly break down quickly or the effects they might have in natural systems!
As part of my work, I have been conducting experiments, exploring how these wipes behave in natural environments. Are they breaking down? How quickly? Are they a hazard to organisms that may encounter them? My initial experiments involved placing commercial wipe products within cages and submerging them in the River Yare for 30 days. One of these products contained a blend of polyester (plastics) and rayon (semi-synthetic form of cellulose), whilst another two contained a blend of cotton and rayon, and a final wipe that contained purely rayon fibres. After the experiment was completed, the wipes were removed, dried, and examined using a scanning electron microscope (SEM).
The site of my first study and the cage setup I used to house the materials.
Using the SEM, I was able to study the individual fibres of the wipes at high magnification, to really understand how their shape and structure may have changed. Each wipe came out of the river covered in biofilm (a sludgy substance made from microbial communities and the goo they excrete for movement, structure and feeding). So, I was expecting some interesting microbial activity, as is common for aquatic environments. However, the images I collected were fascinating and unexpected!
Before: A SEM look into wet wipe fibres. Here we have clean plastic (smooth) and rayon (ribbed) fibres from a set of baby wipes.
After: The same wipes after exposure in the river Yare for 6 weeks. You can clearly see the thick biofilm binding each fibre together, with beautiful diatom frustules (centre) caught in the film. This demonstrates the diversity of life on things even as mundane as a wipe!
Each wipe had a thick biofilm composed of beautiful diatoms, a type of golden brown algae that lives in all bodies of water, famous for their contribution to atmospheric oxygen production and the beautifully geometric frustules (shells) they create (See pictures). These films also had considerable amounts of extracellular substances (the goo microbes excrete). However, less was observed on the plastic wipes. These polyester fibres also showed little to no degradation at all, being a smooth and uniform as when they were first produced. The rayon fibres on the other hand, were significantly degraded, showing intricate termite-like tracks through the fibre structure, at scales nanometres across! This would be too small for the action of worms, and bacteria do not make tracks when digesting materials, so what this may have been I am unsure, but my colleagues believe it may be some sort of microscopic fungus! I will hopefully investigate further to understand exactly what organisms may be living on and eating these materials. This could help us further understand how biodegradable materials behave, so that we can ensure waste management practices are efficient and sustainable!
An even closer look: at 1500x magnification, you can clearly see the beauty of these diatoms, as well as the degradation of each fibre. Originally these were smooth and clean, now they are host to all sorts of organisms, as a refuge and food source.
Interestingly, the cotton fibres showed little degradation compared to the semi-synthetic rayon, and at the end of six weeks exposure, all materials were still present. This raises some questions about how long materials may actually last in the environment. If they are lingering on for longer than we expected, what impacts may they have on the ecology around them? If these fibres are also impregnated with hazardous chemicals, what does their degradation mean for the release of these compounds? Certain groups of organisms, such as invertebrates like mussels, oysters and worms, may be regularly exposed to microplastic pollution. We have extensively studied the effects these pollutants might have on invertebrate health and functioning. However, we still have not reached a consensus on how harmful plastics may be to them. And what about biodegradables? Little research has been conducted on how biodegradable and non-plastic materials may impact organisms that may become increasingly exposed to them as policies change to minimise plastic use and finding alternatives. My future research will delve deeper into this.
As I continue my PhD, I will keep the SCIEnvy blog updated, so I hope you will continue to join me on my research journey!
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