Corn plastic may not be as green as you might think

Corn plastic is hyped as a green alternative to petroleum-based plastic polyethylene terephthalate (PET), the stuff of almost all consumer packaging. Wal-Mart, for example, introduced it in some packaging as part of their "big corporate goals for the environment." Advocates tout that the corn plastic, formed from polylactic acid (PLA) resin, is biodegradable and can be composted into fertilizer. And it can. Under the right conditions. In the new issue of Smithsonian, writer Elizabeth Royte digs into whether the corn plastic is as good as it sounds. Apparently, it's not. From the article:

…PLA is said to decompose into carbon dioxide and water in a "controlled composting environment" in fewer than 90 days. What's a controlled composting environment? Not your backyard bin, pit or tumbling barrel. It's a large facility where compost–essentially, plant scraps being digested by microbes into fertilizer–reaches 140 degrees for ten consecutive days. So, yes, as PLA advocates say, corn plastic is "biodegradable." But in reality very few consumers have access to the sort of composting facilities that can make that happen. (PLA manufacturer) NatureWorks has identified 113 such facilities nationwide–some handle industrial food-processing waste or yard trimmings, others are college or prison operations–but only about a quarter of them accept residential foodscraps collected by municipalities…

Wild Oats accepts used PLA containers in half of its 80 stores. "We mix the PLA with produce and scraps from our juice bars and deliver it to an industrial composting facility," says the company's Tuitele. But at the Wild Oats stores that don't take back PLA, customers are on their own, and they can't be blamed if they feel deceived by PLA containers stamped "compostable." (The president of compost research lab Woods End, Will) Brinton, who has done extensive testing of PLA, says such containers are "unchanged" after six months in a home composting operation. For that reason, he considers the Wild Oats stamp, and their in-store signage touting PLA's compostability, to be false advertising.

Wal-Mart's (VP of private brands and product development Matt) Kistler says the company isn't about to take back used PLA for composting. "We're not in the business of collecting garbage," he says. "How do we get states and municipalities to set up composting systems? That is the million-dollar question. It's not our role to tell government what to do. There is money to be made in the recycling business. As we develop packaging that can be recycled and composted, the industry will be developed."