Products made of biodegradable plastics were just as likely to damage the marine environment as those made using standard materials, while labeling claims concerning their “green” credentials could confuse the public, according to the United Nations.
A UN report, “Biodegradable Plastics and Marine Litter: Misconceptions, Concerns and Impacts on Marine Environments,” argued that oxo-degradable plastics do not rapidly break down in the sea and therefore “manufactured items will continue to cause littering problems and lead to undesirable impacts.”
Consumers could be led, mistakenly, to conclude that an item made of biodegradable plastic would dissolve away into nothing and need not be disposed of responsibly, the UN said.
In addition, some of the claims — and counter-claims — made about particular types of polymers and the likelihood of their biodegrading in the environment “appear to be influenced by commercial interests,” the report said.
It went on: “Some evidence, albeit limited, suggests that public perceptions about whether an item is biodegradable can influence littering behavior, for example if a bag is marked as biodegradable it is more likely to be discarded inappropriately.
“On the balance of the available evidence, biodegradable plastics will not play a significant role in reducing marine litter.”
The report was published to coincide with the 20th anniversary of the Global Program of Action for the Protection of the Marine Environment from Land-based Activities.
Achim Schmidt, executive director of the UN's Environment Program (UNEP), said recent estimates from his organization had shown 20 million metric tons of plastic ended up in the world's oceans each year.
“Once there it does not go away, but breaks down into microplastic particles,” he said. “This report shows there are no quick fixes, and a more responsible approach to managing the lifecycle of plastics will be needed to reduce their impacts on our oceans and ecosystems.”
In a response to the UN's report the British Plastics Federation (BPF) defended the versatility and benefits of plastic, but acknowledged that biodegradable materials were not the answer to marine litter.
“The key issue is to prevent plastics going into the environment in the first place,” the trade body said.
“A mix of solutions is required, including behavioral change, increased recycling and the adoption of sound waste management practices by a whole host of stakeholders including shipping lines, owners of leisure craft, port authorities and coastal local authorities.
“The industry itself has taken steps to prevent plastic pellets from plants entering the environment through the adoption of Operation Clean Sweep and is actively in dialogue with other stakeholders through the Marine Litter Action Network, coordinated by the Marine Conservation Society.”