Can I reuse corn-based 'plastic' containers?

May 31, 2008 3:40 PM

Can I safely reuse a 'plastic' clamshell made of corn?

I've been buying my salad mix in clamshells that purport to be made of corn. I'm assuming they mean PLA or something like it.

I know bioplastics are compostable (under the right conditions) and biodegradable, but it occurred to me that in theory the container should be reusable as well, for a time. This strikes me as a good option in part because a) I don't have access to a compost heap, and b) I know these containers won't compost properly in a landfill.

Here's my theory: so long as I don't fill up the clamshell with hot food and melt it, there's no health risk, since the only thing that could leach into my food is corn. Logical, or crackpot? Eventually I expect the container would start to break down, but I'm not actually sure about this, since my fridge/cupboards/etc are not exactly optimal composting conditions.

So I guess there are two questions here: 1) Is it safe, healthwise, to reuse plant-based containers? And 2) What happens when you do?

posted by lindsey.nicole to health & fitness (4 comments total)

PLA melts at 173 C, so you're not likely to melt it with hot food. That said, it's only food safe up to about 60 C. It's compostable over about 180 days, but that's in a composting environment. It's not going to biodegrade quickly if you re-use it.

the only thing that could leach into my food is corn.

It's not corn anymore; it's plastic. I've found no toxicity information, but I'd try to avoid eating it.
posted by ten pounds of inedita at 4:24 PM on May 31, 2008

I was given a free travel mug which said it was made from corn which i assume is made of the same plastic and it is meant to be reused with hot drinks so i would assume yours to be reusable as well.
posted by humanawho at 5:25 PM on May 31, 2008

Seems to me that for a biodegradable plastic, hot food and melting would be less of a concern than spoiled food and rotting.

So if you've used a biodegradable container to host one of those share-house back-of-the-fridge biological experiments, the surface of the plastic is likely to have been somewhat etched by the things living inside, and might well be impracticable to clean.
posted by flabdablet at 7:30 PM on May 31, 2008

Trust it as much as you'd trust any packaging plastic, meaning maybe not so much as you probably are, because plastic isn't really inert. Generally it's not the primary polymer so much as the performance additives, and I know they do put additives in PLA. PLA has nothing to do with corn, chemically. There is nothing in it you'd recognize as corn. And while biodegradable plastics (to be certified thus by, say, ASTM) are supposed to break down into constituents nontoxic to the ecosystem, well, you know, you'd think plastics wouldn't be supposed to be leaching hormone-mimicking compounds into every corner of the globe. But they do.

On the other hand I don't fret too much about it and I had to learn a ton about it all, a long time ago. I don't worry about short term storage but I'm increasingly reluctant to reheat food in plastic. As a short term storage package feel free to reuse this stuff as you would a polyethylene container.
posted by nanojath at 10:09 PM on May 31, 2008