Biodegradable plastic bags need to be collected separately to avoid contaminating the waste stream, according to the European Plastics Converters Association (EuPC).
The organization has published a report, carried out by the Austrian Transfer Center for Polymer Technology, regarding the effects of degradable plastics on the quality of plastic recyclates.
The tests, conducted over the course of six months, focused on four different mixtures of degradable plastic bags and one virgin low density polyethylene recycling material. The analysis was carried out on 9.5 tonnes of plastic carrier bags and featured more than 3,700 measurements.
These showed that even in quantities as low as 2 percent, degradable plastic films cause significant, detrimental effects on the quality of plastic recyclates. These are not only detrimental in terms of mechanical properties of the recycled material but also involve visual impacts on the newly produced film, according to Brussels-based EuPC.
Commenting on the test results, EuPC managing director Alexandre Dangis said: "Over the past years, there has been considerable concern in Europe surrounding the effects of bio-degradable plastics on recycling streams.
"These test results now prove that separate collection of degradable plastic products is needed in Europe if we want to further develop recycling streams and work towards a circular economy."
However, Vancouver, British Columbia-based EPI Environmental Products Inc., a manufacturer of degradable additives, said the EuPC report was "of poor scientific quality, plagued by methodological flaws and scientific inconsistencies that raise substantial doubt about the credibility of the data and, thus, the conclusions of the report."
Joseph Gho, EPI's president and CEO, said: "It would not only be most imprudent, but also be a mockery of science, if governments or businesses were to ignore the environmental benefits of oxo-biodegradable plastics and act prejudicially against it.
"The means of achieving best-environmental practice is clear — only through a balanced portfolio of sustainability strategies, with oxo-biodegradable technology featuring prominently amongst them, can the environmental impact of plastic usage be minimized successfully."