PLA, or corn plastic, is made with Midwestern corn, not Middle East oil. Its production releases fewer toxic substances than making petroleum plastic and uses less energy, spewing an estimated two-thirds less greenhouse gas.

And corn plastic can be composted, incinerated or recycled, its manufacturer says, offering "the most alternatives" of any plastic to landfilling.

Even so, Oregon's recycling pros are awfully down on it.

Why? Corn PLA, made mainly by Minnesota-based Natureworks, composts only in high-temperature commercial composting systems, not backyards. It's difficult to distinguish from regular plastics in the recycling mix. And a small amount can foul recycling of conventional plastic, one of the biggest-payoff items for recyclers nationwide.

"As a regular resident, you can't compost it. You can't recycle it," says Lauren Norris, coordinator of the Portland area's master recycler program. "Really, you're giving people something that has to be landfilled."

Like ethanol, biodiesel and wind power, PLA was widely lauded at first blush. Five years later, it's moving into the consumer mainstream -- and getting the critical second look typical when green breakthroughs scale up.

The scrutiny is particularly relevant in Oregon. Kroger, owner of Fred Meyer, QFC and other grocers, is the first national chain to carry Primo water, packaged in the first corn plastic water bottle intended for U.S. grocery shelves.

Recycling advocates say PLA water bottles sold at retail are most likely to contaminate recyclables. That threat is greatest in states where recycling's high because of "bottle bills" -- return deposits on bottles and cans.

Oregon's nickel deposit for plastic water bottles takes effect Jan. 1.

With other grocers, the Kroger subsidiaries and Trader Joe's also carry other PLA containers, including packaging for organic salad greens and herbs, fruit and specialty items.  

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