The five chosen bags 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 compostable according to European Norm 13432, said the EUBP. “Most of the bags selected are not biodegradable according to European Union definitions in the first place. Indeed only one product is—the compostable bag,” said Hasso von Pogrell, Managing Director of EUBP. “But the scenario of industrial composting, for which the item was designed, was not tested.”
According to EUBP, the bag described as biodegradable was allegedly tested according to ISO 14855. This standard describes merely a test method without clear pass/fail criteria that could serve as a basis for proper biodegradability claims and labeling. Therefore, the study actually highlights the importance of correct labeling and certification and reinforces what the EU Commission already did with the Single-use Plastic Directive, where oxo-degradable plastics have been extensively researched by the European Commission and banned.
Professor Richard Thompson, Head of the International Marine Litter Research Unit at the University of Plymouth, said: “This research raises a number of questions about what the public might expect when they see something labeled as biodegradable. We demonstrate here that the materials tested did not present any consistent, reliable and relevant advantage in the context of marine litter. It concerns me that these novel materials also present challenges in recycling. Our study emphasizes the need for standards relating to degradable materials, clearly outlining the appropriate disposal pathway and rates of degradation that can be expected.”
The EUBP expressed concerns about compostable bags and the testing procedures used. “Plastic products certified to be industrially compostable are no solution for littering. Testing them as if they should be is misleading the public’s perception of the technology,” said von Pogrell. “It creates the impression of the product lacking in performance, even though the performance in the intended environment has not been tested at all.”
Certainly, the testing of the various types of plastic retail carrier bags sheds some light on what the terminology actually means when promoted as “oxo-degradable” or “biodegradable” or “compostable.” It lends some doubt as to the credence of these claims. It also heightens the concerns that none of these so-called solutions are truly what they claim and that plastic litter will be with us for millennia because of people who choose to throw all types of waste products into the environment.
"Give up the biodegradability myth," says chemical engineering professor
Several years ago at an SPE thermoforming conference, Ramani Narayan, a chemical engineering professor specializing in polymeric materials from renewable resources and biodegradable polymeric systems at Michigan State University, gave a presentation in which he noted that there are many misleading biodegradability claims in the marketplace—all we have to do is put an additive into the plastics and the material will magically disappear.