Pros and Cons of PLA: Corn-Based Plastic
Sept. 15,2017   

 Polylactic acid (PLA), a plastic substitutemade from fermented plant starch (usually corn) is quickly becoming a popularalternative to traditional petroleum-based plastics. As more and more countriesand states follow the lead of China,Ireland, South Africa, Uganda and San Francisco in banningplastic grocery bags responsiblefor so much so-called “white pollution” around the world, PLA is poised to playa big role as a viable, biodegradable replacement.    Proponentsalso tout the use of PLA — which is technically “carbon neutral” in that itcomes from renewable, carbon-absorbing plants — as yet another way to reduceour emissions of greenhousegases in a quicklywarming world. PLA also will not emit toxic fumes when incinerated.   

 However,there are still issues with the use of polylactic acid such as its slow rate ofbiodegradability, its inability to mix with other plastics in recycling, andits high use of genetically modified corn (though arguably the latter could beone of the good effects of PLA as it provides a good reason to alter cropyields with genetic splicing).   


Geneticallymodified foods may be a controversial issue, but when it comes to geneticallyspicing plants together to breed corn that yields more crops for industrial usehas its major advantages. With increasing demand for corn to make ethanol fuel,let alone PLA, it’s no wonder that Cargill and others have been tampering withgenes to produce higher yields. At least harmful plastic isn't be used asfrequently anymore!   

 Manyindustries are using PLA because they are capable of biodegrading at a muchfaster rate than plastic while still offering the same level of sanitation andutility. Everything from plastic clamshells for food take-out to medicalproducts can now be made from PLA, which drastically reduces the carbonfootprint of these industries.   

 WhilePLA has promise as an alternative to conventional plastic once the means ofdisposal are worked out, consumers might be better served by simply switchingto reusable containers — from cloth bags, baskets and backpacks for groceryshopping (most chains now sell canvas bags for less than a dollar apiece) tosafe, reusable (non-plastic) bottles for beverages.   


 Criticssay that PLA is far from a panacea for dealing with the world’s plastic wasteproblem. For one thing, although PLA does biodegrade, it does so very slowly.According to Elizabeth Royte, writing in Smithsonian,PLA may well break down into its constituent parts (carbon dioxide and water)within three months in a “controlled composting environment,” that is, anindustrial composting facility heated to 140 degrees Fahrenheit and fed asteady diet of digestive microbes.   

 Butit will take far longer in a compost bin, or in a landfill packed so tightly that no light andlittle oxygen are available to assist in the process. Indeed, analysts estimatethat a PLA bottle could take anywhere from 100 to 1,000 years to decompose in alandfill.   

 Anotherissue with PLA is that it must be kept separate when recycled, lest itcontaminates the recycling stream; since PLA is plant-based, it needs to bedisposed of in composting facilities, which points to another problem: Thereare currently a few hundred industrial-grade composting facilities across theUnited States.   

 Finally,PLA is typically made of genetically modified corn, at least in the UnitedStates. The largest producer of PLA in the world is NatureWorks,a subsidiary of Cargill, which is the world’s largest provider of geneticallymodified corn seed. This is tricky because the future costs of geneticmodification (and the associated pesticides) to the environment and humanhealth are still largely unknown.

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