Oxodegradables consist of standard polyolefins with additives that accelerate fragmentation under given environmental conditions. But this is not the same as the biodegradation that takes place, for instance, in compostable packaging.
"One of the themes that came out of our research is that people risk being confused," said Loughborough's Dr Andy McLauchlin. "Terms like this need to be clear."
He added: "There are documented instances where legal action has been taken to stop manufacturers from describing their products as 'biodegradable'." They are suitable neither for mechanical recycling nor for composting, said the report. Among other findings, said DEFRA, the study highlighted the uncertainty about the impact of the tiny plastic particles which result.
Environment minister Dan Norris said: "We hope this research will discourage manufacturers and retailers from claiming that these materials are better for the environment than conventional plastics."
Harald Kaeb, president of European Bioplastics, said the study confirmed its own findings, highlighting the need to "raise awareness of questionable marketing claims" and end "growing marketplace confusion".