Last updated May 24, 2018 at 4:07 pm
New research destroys the cosy thinking round ‘greener’ alternatives.
A biodegradable plastic bag can do an awful lot of damage until it breaks down – and even then we are unsure of its impact. Credit: iStock
Purchasing biodegradable plastic bags seems like a positive change for any concerned citizen trying to play their small part in the war on waste, but a new review into the biodegradable nature of plastic shows that it might not be as clear cut as we had hoped.
Plastic bags
The humble plastic bag has become synonymous with pollution.
Nowhere is this truer than in the marine environment where we illustrate our impact on the environment by pointing at the disgusting mass of discarded products circling the globe and collecting in places like the great pacific garbage patch.
Many Australian states have started banning plastic bags and sales of eco-friendly products have increased as people become aware of the environmental legacy of their disposable lifestyle.
Biodegradable plastic seemed to be the answer.
It promised to balance our desire for convenience with the need to protect the environment. But, this latest study illustrates that we must be careful when defining what we mean by ‘biodegradable’.
“This research helps destroy the thinking a plastic bag with a label ‘biodegradable’ is safe for the environment,” said Professor Thomas Neitzert, President of Engineers for Social Responsibility who was not involved with the study.
International industry standards
A team of European experts took existing international industry standards and regional test methods for evaluating the biodegradability of plastics within aquatic environments and found that they were insufficient in predicting the biodegradability of single-use plastic carrier bags.
“As with many standards, there is a gap between laboratory testing and the outside world with its constant changing conditions in this case concerning seasons, temperatures and concentrations of chemicals,” said Professor Neitzert.
The researchers also found that the current tests to not adequately test for toxicity once the plastic enters the marine environment or account for the increased risk to marine life once it has fragmented into smaller particles.
“A biodegradable plastic bag is potentially dangerous to marine life from the moment it enters the water until it dissolves into micro- or nanoparticles over many years” says Prof Neitzert.
Simply, we don’t know enough about how these materials will break down in the environment, which is essential to work out before we jump into another type of bag that may cause a different set of problems.
“In moving forward, a lot is dependent on the expectations we can have on responsible human behaviour in terms of stewardship (education, legislation) but there is much to be done on ensuring as little environmental impact as possible through controlled degradation and ensuring the products of these are not harmful,” says Professor Kim Pickering from the University of Waikato who was not involved with the study.
Maybe it is time to dig out your cloth bags from the depths of the kitchen drawers and stay away from any type of single use plastic for the time being – the environment will thank you!
The research was published in Royal Society Open Science.
