EUBP says UK study on plastic bag decomposition “misleading”

European Bioplastics (EUBP) has played down the results of a recent study by the University of Plymouth, which examined the environmental impact of plastic carrier bags in the environment over a 3-year period.
 
The study carried out by Imogen Napper and Richard Thompson of the University of Plymouth tested biodegradable, oxo-degradable, compostable and HDPE conventional carrier bags by giving them long-term exposure to open air, soil and the sea. 
 
The research found that the bags did not fully decompose in all those environments, expect for the compostable bag, which completely disappeared after three months of exposure to the sea.
 
In its conclusion, published 28 April, the study said it was not clear whether the oxo-biodegradable or biodegradable formulations provided “sufficiently advanced rates of deterioration” to help reduce marine litter, compared to conventional bags.
 
In response to the findings of the research, EUBP said the study highlighted the important issue of correct labelling and the potential positive impact of biodegradable and compostable bags on the environment.
 
“Contrary to what the headlines of some newspaper reports picking up the findings suggest, the study confirms that only certified biodegradable and compostable bags – designed to be collected with the bio-waste and organically recycled in dedicated composting plants – even if mistakenly littered in the environment due to bad habits, have a reduced environmental impact”, said François de Bie, EUBP chairman.
 
“At least,” he added, “it is clear that certified compostable ones will not need decades to degrade, as conventional plastic bags do.”
 
According to EUBP, the five bags tested included two oxo-degradable bags, one fossil non-biodegradable polyethylene bag, one bag marketed as – but not proven to be – biodegradable, and one product certified as compostable according to the European Norm 13432.
 
“Most of the bags selected are not biodegradable according to EU definitions in the first place – indeed only one product is: the compostable bag,” Hasso von Pogrell, EUBP managing director pointed out.
 
However, according to Von Pogrell, the scenario of industrial composting, for which the compostable bag was designed, was not tested during the study.
 
Furthermore, according to EUBP, the bag defined as biodegradable was labelled as such according to the standard ISO 14855.
 
This, EUBP said, is not a standard on biodegradation but merely specifies a “method for the determination of the ultimate aerobic biodegradability of plastics, based on organic compounds, under controlled conditions.”
 
“Therefore, the study actually highlights the importance of correct labelling and certification,” the association added.
 
To conclude, EUBP stressed that plastic products certified to be industrially compostable were not a solution for littering.
 
“Testing them as if they should be, is misleading the public’s perception of the technology. It creates the impression [that] the product [is] lacking in performance, even though the performance in the intended environment has not been tested at all,” Von Pogrell added.
 
According to EUBP, two research projects - Plastic Leak Project and the H2020 project CLAIM - are currently underway to shed new light on how to reduce litter and plastic leakage.