Corn plastic is bad. While it may look "less bad" than petro-plastic, it's making things worse, for these reasons:
1. While it does biodegrade, it doesn't do so as easily as similar containers from paper or sugar cane.
2. It appears to be messing with the existing petro-plastic recycling culture, a system already struggling with vast and intractable consumer ignorance.
3. Making a corn-based "substitute" uses MORE PETROLEUM than the petro-based one it's supposed to replace.
4. It directly supports Cargill Corporation, which you don't want to do for too many reasons to list here (visit Grist.org, search Cargill, and pick your issue. Whatever it is, they'll be on the wrong side of it.)
Here's detail I copied from a posting by Dr. Dan Wolk on the subject:
Here's some useful information on the cups we're using at Mishkan, from
grist.org (where I go for answers to the most perplexing environmental
"Corn and other bio-based plastics are particularly tricky because to the
casual observer, it looks like regular petroleum based plastics. There is
evidence that recycling as little as 1 part of PLA in 10,000 of PET
(Petroleum based polyethylene terepthalate) will degrade the quality of PET
and render it unusable as a recycled polymer. This is a huge problem for
recyclers and the source of great debate among bottlers and recyclers as
some companies have started bottling their beverages in PLA bottles. PLA
bottles are NOT recyclable with PET (though they could be fed back into the
PLA stream... Cargill does not have a collection system to recycle PLA so
this point is moot) but they look just like it to the casual observer. Thus,
unknowing recyclers can contaminate the PET bottle recycling stream
by placing PLA bottles with their regular recyclables. NAPCOR (National
Association of PET Container Resources) recently publicly refuted claims of
recyclability of PLA.
am no fan of petroleum based plastics either, but to tout bio-based plastics
as being "green" is disingenuous and very confusing to people who are trying
to employ environmentally preferable practices. If you want a compostable
cup use paper!"
After reading all about it, including a response from Cargill's
sustainability director, the only advantage of the "corn" cups is that
they're not made directly from petroleum (though growing corn uses LOTS of
it!). They're not recyclable, and compostable only in a commercial
operation. Plus, their purchase supports a rather environmentally
The best alternative? Bring your own cup. If you're prone to leaving
those behind, as I am, the next best alternative: cups made from sugar cane
fiber (bagasse) - an agricultural waste product. Cost: 8 cents each - the
same as the "corn" cups.
In honor of Shavuot, I humbly recommend switching to the Bagasse cups when it's time to reorder..