Camilla Catarci Carteny

Source: Credit: Camilla Carteny, UAntwerpen

How sea-friendly is biodegradable plastic?

More and more packaging, not only for food, is made from so-called biodegradable plastic. It’s part of the ‘plastic soup’ that ends up in the ocean. Is its impact comparable to that of ordinary plastic? Camilla Carteny is looking for answers in a real-life simulated marine environment.

The issue of plastic pollution in oceans and coastal waters has received increased attention in recent years. The global ‘plastic soap’ regularly crops up in the news. Most part of the waste consists of ordinary plastic, but also biodegradable plastic which accounts for a growing share of the packaging waste, ends up in the sea. Despite its environment-friendly image, its impact on marine environments and sea life is still unknown. In fact, biodegradable packaging was designed primarily to reduce the plastic waste mountain (on land) and to control litter.

As part of her PhD Fellowship in Strategic Basic Research at the University of Antwerp, FWO researcher Camilla Catarci Carteny is currently investigating the behaviour of biodegradable plastic in a natural marine environment. “For this I use a water tank exposed to natural sunlight,” says Carteny. “This has never been done before in this type of research. Previously, artificial light was used. This makes an important difference.”

In her first experiment, Carteny had different plastic films - both biodegradable and conventional ones - floating and suspended in the tank water. She came to the remarkable conclusion that the biodegradable plastic does not degrade as easily as the ordinary plastic.

But that is not the only reason why biodegradable plastic is (probably) even worse for the marine environment than ordinary plastic. In a follow-up experiment, Carteny discovered that the packaging material also attracts and absorbs more toxic substances and pollutants (e.g. organic substances such as PCBs, which often also occur in seawater). “We don’t exactly know why this is so. One reason could be that biodegradable plastic is more porous, or possibly the interaction with water bacteria could play a role.” In any case, this could further exacerbate the problem, for if the plastic breaks down into microscopically tiny particles (“microplastics”), these end up in the marine food chain

Finally, Carteny is therefore studying the impact that microplastics from biodegradable material have on sea life, again as compared to ordinary microplastics. The results of this research, in which Carteny measures toxicity in fish, are not known yet.

Although her research is still ongoing, preliminary conclusions suggest that biodegradable plastic is only meaningful if accompanied by an adequate collection and segregation policy and suitable processing infrastructure. “Ideally, biodegradable plastic is processed in an industrial composting plant, where it degrades much more easily than ordinary plastic (which does not degrade). Just as long as it does not end up in the sea.”

Credit pictures: Camilla Carteny, UAntwerpen