Polystyrene Found To Break Down In Decades Rather Than The Thousands Of Years Previously Predicted

Polystyrene, a plastic typically used for various materials from takeaway boxes to packaging materials, was previously thought to take thousands of years to degrade. However, a recent study has shown that the material can break down in as little as several decades, according to Daily Mail.

Collin Ward, of the Woods Hole Oceanographic Institution (WHOI), and his colleagues set out to discover if polystyrene really lasts "forever," as previously thought, or if it is possible for it to degrade over time. They argue that government policy makers and scientists may have been working without knowing the full facts.

"Policymakers generally assume that polystyrene lasts forever in the environment," Ward commented. "That's part of justification for writing policy that bans it."

The scientist added that he and his colleagues did not set out to prove that plastic pollution isn't bad, just that the persistence of polystyrene in the environment may be shorter and likely more complicated than previously understood.

"The chance for injury to the environment over decades is still available."
The researchers found that by using a sun-simulating lamp, the polystyrene was capable of chemically degrading slowly while releasing organic carbon and trace amounts of carbon dioxide. When exposed to the ultraviolet (UV) component of sunlight, the material slowly turned yellow and brittle.

A person holds up a polystyrene cup filled with a steaming liquid.
Unsplash | Caleb Lucas

Ward compared the yellowing and breaking down of polystyrene to that of other types of plastic -- such as plastic playground toys, park benches, and lawn chairs -- that are capable of becoming sun-bleached after being outside for a significant period of time.

Sunlight doesn't just cause the materials to break down but changes them chemically, forming dissolved carbon and trace amounts of carbon dioxide. The scientists reported that the carbon dioxide released is not enough to impact climate change.

Previous research on polystyrene and other plastics studied how plastic-eating microbes degrade the materials, as opposed to other factors such as sunlight. These plastic-eating microbes can be selective, however, shying away from the complex and bulky structure of polystyrene and focusing on other types of plastic.

While Ward affirmed that the methods used in his lab all point to the same outcome that sunlight can transform the polystyrene into CO2, further research is needed to better understand what happens to the other products that dissolve into water, including their impact on the environment.

The complete findings of the study can be located in the journal Environmental Science and Technology Letters.