Think green plastics are best? Think again

McClatchy-Tribune Information Services

"Green" plastics apparently aren’t as green as you’d think.

It turns out most commercially available bio-plastics — plastics made from crops such as corn and coconut fiber — biodegrade poorly, researchers at Ohio State University’s Ohio Agricultural Research and Development Center in Wooster Township have found.

"And in some cases, bio-plastics can be worse for the environment than fossil-fuel-based plastics when taking into account inputs needed to grow crops from which these products are made, land and water use, and the greenhouse gases released from these plastics when they do break down," Fred Michel, a biosystems engineer at the center, said in a news release about the study.

The study was conducted by Michel and Eddie Gómez, a recent Ph.D. graduate. It was published in the December issue of the journal Polymer Degradation and Stability.

The study tested plastics made from natural materials as well as petroleum-based plastics with additives that are supposed to help them break down. Almost all did a poor job of decomposing all three environments in which they were tested — compost, soil and an anaerobic digester.

Only one bio-plastic, made via sugar fermentation, biodegraded sufficiently, the study found.

To make the matter even more complicated, Michel pointed out that petroleum-based plastics made from polylactic acid, also known as PLA, are biodegradable.

"When it comes to biodegradability, talking about fossil fuel-based versus bio-based plastics does not make much sense," he said.

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