News Jan 17, 2008 at 4:00 am

High Expectations


I read recently that a bill has been proposed in Washington state which requires that plastic bags used in grocery stores be made out of PLA (a corn based plastic.) This proposed bill is based on misconceptions which have been spread by the PLA lobby, which sells plastics made out of corn. This lobby is funded by the Dow Chemical Company, Cargill Inc., and ADM. These corporate giants make non-food items out of corn. Making non-food items out of grain is what caused last year's spike in grain prices. The part of oil, naphtha, that is made into plastic is not something that could be used for making anything else-it is not potential gasoline or diesel, for example. It was regarded as a waste product and burned off before we started making it into plastic.

There are a lot of problems with PLA - If we made all of the plastic disposable items used in the world every year out of PLA, it would take one hundred and fifty million tons of corn to make it. That would lead to mass starvation in the third world, as that represents at least 10% of the world's grain supply. It also takes a huge amount of oil to grow, fertilize, ship, and process this corn, and as a practical matter, it is also not recyclable-In fact, the recyclers are trying to get PLA banned because it gets mistaken for PET, and ruins their PET batches. Restaurant owners and merchants find it annoying that PLA becomes gummy in water, gives water stored in it an odd taste, softens at soup temperatures, and has a short shelf life. PLA is weaker than conventional and biodegradable conventional plastic, and more expensive per pound, as well. Also, PLA can't be composted at home-it takes the elevated temperatures of a commercial composter to compost PLA.

If PLA is placed into land fills, it gets buried so deeply that it is in a zone free of oxygen. Then anaerobic microorganisms digest it, releasing methane gas. PLA is consumed so quickly that the land fill is not capped before it creates methane, so all of that methane is released into the atmosphere, where it causes global warming. Some biodegradable plastics that are not corn based will also release methane if they are digested by anaerobic bacteria, but they do so so slowly that the land fill is capped before methane is released. When the land fills are capped, the methane is either burned off or it is used as a heat source for industrial uses, such as generating electricity.

In short, requiring grocery bags to be made out of PLA would be a counterproductive law which would enact a tax on the public for the benefit of socially irresponsible corporate giants. The alternative? Recyclable biodegradable plastics-Plastics made out of an otherwise useless industrial byproduct, naphtha, which have a harmless additive in them that makes them biodegrade. See for full information.

-Tim Dunn, Arlington WA

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