The dangers of degrading plastic

Australian researchers are using the tracer principle to confirm the presence of plastics and chemicals in the food chain. The research began when Professor Richard Banati from ANSTO and Dr Jennifer Laver from Monash University found elements in the feathers of seabirds which were similar to those found in plastics in its gut.

Plastic items were collected from the stomachs of Flesh-footed Shearwater birds over an extended period, and the Australian Synchrotron in Melbourne was used to measure chemical composition of the plastic samples. A process called neutron activation was then used, where neutrons from the OPAL reactor in Sydney were bombarded against samples, making them slightly radioactive and enabling their giving off a measurable gamma spectrum. Scientists then put the samples into a gamma counter to measure the energy of the particles.

The researchers found that plastics floating in the oceans have a complex degradation process which makes them potentially more, rather than less, hazardous than previously thought. The process of degradation is made more complex by the fact that plastics, many of which have been recycled already, are a mix of many components.

During the process of degrading, plastics, including biodegradable plastics, break down into smaller and smaller pieces, meaning their surface area increases dramatically. Greater surface area means greater interaction with the environment, which means degraded plastics both release more toxins such as cadmium and mercury into the environment, and attract and absorb more.

“A traditional approach to environment management has been ‘the solution to pollution is dilution’; however, researchers are becoming concerned about this approach,” said Professor Banati.

“Specifically we are finding that mass plastic consumption, together with increased degradability of plastics, may actually lead to a steady increase of hazardous contaminants in the environment which would be difficult to reverse.

“We need to be mindful that remnants of seemingly ‘single-use’ items often stay in ecosystem for a very long time and do not simply disappear, but continue to move through the environment, and the plants and animals therein.

“What we have done is show that the traceability of plastics, from a scientific perspective, allows an analysis of the life cycle of plastic that extends well beyond the litter than we can see.”

Professor Banati said he hopes his work fosters a new understanding of plastic based on science at the atomic level, raising questions about environmental, biological and social issues.

“Should we be further emphasising use of quality, re-usable products? Are industry standards for biodegradable plastics appropriate? Should we find a way of further incentivising plastic collection?” he asked.

“These are interesting questions and, if anything, what research at the atomic scale shows is that they are at least worth putting out there and discussing.”