April 19, 2024

I, Science

The science magazine of Imperial College

There are plastics at play at much finer scales, invisible to our eyes, but no less harmful.

We’ve all seen footage of sea birds with six-pack rings around their necks; of dolphins caught in discarded fishing nets; of plastic bags removed from the stomachs of dead turtles. Many of us will have recently watched Blue Planet II. The visuals evoke a response in us: we can see the harm, what we have contributed towards. However, the bags and the nets and the forks are not the full story. There are plastics at play at a much finer scale, invisible to our eyes, but no less harmful.

A significant type of this fine-scale plastic is known as microbeads, which are defined by their size – typically being less than 1mm across. Some larger plastic items break down over time to become microplastics, but microbeads are specifically manufactured at these small sizes, to be used in products such as toothpastes, suncreams and as exfoliants. They are also used in scientific research, mostly in the fields of biomedicine and biotechnology where their use has aided medicine and disease prevention. They can be coupled with biomolecules such as antibodies, used as visual markers in microscopy and fluid flow visualisations, as well as a variety of other innovative techniques.

Too small to be removed by the filters in our sewage systems, the beads flow out into rivers, canals and out to sea. It is estimated that a single shower can result in 100,000 plastic particles entering the ocean, contributing to the eight million tonnes of plastic that enter our seas every year. Microbeads are a significant piece of the vast plastic pollution puzzle. Unlike larger plastics which can be eaten, and choked upon, by seabirds, turtles or fish, microbeads enter the food chain from the bottom. They are eaten by plankton, hindering their growth. When the plankton are eaten by larger animals, the microbeads are passed on and enter the bodies of these animals. Plastics have been found in samples of fish that are meant for human consumption, but research on the potential impacts of this discovery has only just begun.

Traditionally, the ocean has been thought of, and treated as, an endless source and sink of resources and waste for us to exploit. Throughout history cultures have revered the bounties of the sea, feared it and wondered at it. We now have the capabilities to explore our oceans and the impact our actions are having on them. What we appear to be observing is striking: we’re emptying our oceans of fish and replacing them with plastics. It feels as though the more we find out, the more hopeless our situation seems.

However, we have seen big policy moves across the world to curb the large, visual plastic waste through things such as bans on single-use plastic cutlery, and plastic bag bans and taxes. The UK government has just released a twenty-five year environmental plan, which among other things aims to cut all avoidable plastic waste by 2042. A ban on microbead manufacture came into force last week, with a ban on sales containing them following later this year. Encouragingly, some areas of research and industry appear to have been pre-emptively adapting: in June, scientists and engineers from the University of Bath announced their development of biodegradable cellulose microbeads that could potentially replace harmful plastic ones. The researchers anticipate they could use cellulose from a range of “waste” sources, including from the paper making industry as a renewable source of raw material. Last year a brewery in Florida developed six-pack rings from brewing by-products that decompose and are safe for marine life to eat. Innovative solutions such as these are all steps in the right direction, but how can we solve problems that we are yet to be aware of? In all likelihood, more negative news and impacts of plastics will emerge in time, but many of the acts of prevention we see are heartening.

Joy Aston is studying for an MSc in Science Communication at Imperial College London

Banner image: Person Hands on Assorted-color Plastic Lid Lot, Pexels