Stubborn plastic turned into food for soil microbes

Two stubborn plastics could be made biodegradable by adding a special ingredient during manufacturing, research suggests.

Polyethylene and polypropylene appear in packaging, bottle caps and car parts, but can linger after escaping waste systems. British company Polymateria developed an additive that helps sunlight and air transform treated plastic into a wax. Soil microbes can then use that wax as food.

In peer-reviewed laboratory tests, three treated samples reached between 91% and 96% biodegradation in soil after 269 to 292 days. Untreated polypropylene tested alongside them biodegraded far less, between 14% and 22%. Researchers also found no significant harm at the tested concentrations to earthworms, seedlings or aquatic organisms.

This is encouraging evidence, not permission to scatter plastic wrappers like confetti! The study used controlled conditions, and several authors work for Polymateria, which funded parts of the research and developed the additive. Independent real-world testing will matter. Even so, a safety net for plastic that leaks beyond recycling systems could stop long-lived litter becoming a centuries-old problem.