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Bioplastics

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We are increasingly seeing all kinds of "bioplastic" alternatives to traditional plastics coming onto the consumer product market. So what are they?

Are bioplastics safe, viable alternatives to traditional plastics?  

The short answer:  It depends...

What are Bioplastics?

Bioplastics can be widely defined as plastics made, at least in part, from renewable biological raw materials and/or which contain additives to make them biodegrade quickly.

They currently account only for about 0.5 percent of global plastics production:  about 1.5 million tonnes of bioplastics in 2012, compared with 280 million tonnes of traditional plastics in 2011. However, some experts predict they could eventually replace 90% of the traditional plastics surrounding us today.

But before getting into the nitty gritty of describing bioplastics, we need to define the basic terminology, which can be confusing and misleading unless properly clarified at the outset.

It is important to distinguish between the terms "bio-based", "biodegradable" and "compostable".  

"Bio-based" refers to the  the "beginning of life" of the product, that is, the origin of what the plastic is made from. Bio-based plastics are made, at least in part, from renewable naturally occurring materials (such as shrimp shells or insect bodies) or more commonly from renewable plant biomass such as corn/maize, wheat, potatoes, soy, tapioca, coconut, sugar cane, wood. This is in contrast to traditional fossil-fuel derived plastics made from carbon sources such as petroleum, natural gas or coal. In bioplastics, the carbon source is biological.  

Now "biodegradable" refers to the "end of life" of the product, that is, what happens to the product when disposed of after its useful life. A bioplastic product is considered biodegradable if it breaks down completely in the natural environment through the action of naturally occurring microorganisms such as bacteria, fungi, and algae. Such microorganisms are able to use the elements of the bioplastic, principally the carbon and nitrogen, as food. 

And "compostable" also refers to "end of life" and in particular whether or not the bioplastic will biodegrade - i.e., break down naturally and completely - in a composting environment, be it a home composter in your backyard or a large-scale industrial municipal composting facility.

Commercial and municipal composting facilities have set levels of heat, aeration and moisture to maximize the activity of the oxygen-requiring microorganisms breaking down the compost. Composting in a home composter is less controlled and generally it will take much longer for things to break down.

Both of these composting methods are in contrast to a landfill, which is an anaerobic (oxygen-free) environment. In a landfill, bioplastics will not readily break down if not exposed to oxygen. And the bioplastics in a landfill that do break down will cause release of the potent greenhouse gas methane, which is produced by the anaerobic bacteria breaking down the material. 

So there are a few key distinctions to make here:  

  • Not all bio-based plastics are biodegradable or compostable. 
  • Not all bio-based plastics are completely made from natural renewable materials - some may also in part be composed of traditional synthetic plastic resins.
  • Bioplastics that are composed of 100% bio-based material can be expected to biodegrade completely.
  • Not all bioplastics are bio-based, some can be fossil-fuel based.
  • Not all biodegradable plastics are bio-based, some can be synthetic, but still biodegradable.
  • All compostable plastics are biodegradable, but all biodegradable plastics are not necessarily compostable.
  • Bioplastics might or might not be recyclable in the same way as traditional plastics.  In general, if a bioplastic is biodegradable, it is not recyclable.

Is your head spinning?

Don't worry it's normal as you learn about bioplastics, and this is just what the greenwashers out there are hoping.

The complexity of this fast-moving, murky field makes it a veritable playground for bioplastic products greenwashed as "biodegradable" when in fact they are made in part from synthetic, petroleum-based ingredients that do not actually biodegrade quickly or completely.

You may have to read the above over a few times before it makes sense, but with this knowledge you are empowering yourself to overcome the rampant greenwashing going on in the current marketplace.

Here's one example... In 2008, Discover began offering a biodegradable credit card made of a special form of polyvinyl chloride (PVC); PVC, by the way, is considered one of the most toxic consumer plastics in existence, but is still used to make most credit cards. This special "BioPVC" is manufactured with an additive (the formulation is a trade secret) which apparently makes the card easy to be broken down by microbes. Discover claims the card "breaks down 99% in nine months to five years in soil, water, compost, or whatever microorganisms are present (e.g. landfills or composts). Plus, the card leaves no toxic effect on the environment."

In her book Plastic: A Toxic Love Story, Susan Freinkel interviewed experts who considered this idea of PVC breaking down naturally and harmlessly as extremely dubious, and even "a load of hooey". One renowned bioplastics expert, Michgan State University researcher Ramani Narayan, tested the claims and found that microorganisms only consume about 13% of the card before the breakdown process plateaus. (Freinkel, pp. 207, 220)

The upshot:  This "BioPVC" marketed as a "biodegradable" plastic is still toxic, petroleum-based PVC, simply blended with an extra chemical additive to make it break down faster. While it might just barely make it into our broad definition of bioplastics because it breaks down faster - though that is clearly questionable - it certainly is not bio-based or eco-friendly. It is still toxic, fossil fuel-based plastic. And it might be even more harmful than normal PVC because its faster breakdown makes it more quickly available in smaller pieces to be eaten by wildlife. (See also the discussion of oxo-biodegradable plastics below.)

Standards and Certifications: How to know if a bioplastic product is really biodegradable 

With all this grey area regarding what is realistically "biodegradable," the best way to know if a product you are considering is biodegradable or not is to check if it has a certification label of biodegradability or compostability. 

There are now several key third party certifications for bioplastics, which are based on controlled tests done in accordance with internationally recognized standards set out by, for example, the International Organization for Standardization (ISO) or ASTM. For example, ASTM D6400 is the key standard determining whether or not a plastic can be composted in municipal or industrial facilities.

So you want to be sure that any "biodegradable" plastic product you are considering purchasing has a third party certification label on it, and that it will biodegrade through whatever biodegrading options are available to you (e.g., home composter, municipal composting facility). 

The key certifications are as follows (as compiled and described by Beth Terry, pp.162-164):

(TABLE TO BE ADDED SOON) 

One of the best resources out there is the Biodegradable Products Institute (BPI) website, which provides an excellent database of 3300+ compostable proudcts currently on the market. If you don't see a label, or just want more information on the biodegradabilty of a product, this is an excellent place to start.

And regarding recyclability, it is best to begin by checking with your municipal recycling facility to find out which, if any, bioplastics are accepted in the normal recycling stream. You can also consult the FindAComposter directory at BioCycle to try and find an industrial composting facility near you that will accept bioplastics. 

Another useful resource is the Sustainable Biomaterials Collaborative, which provides all kinds of information on bioplastics including:  sustainability guidelines, lifecycle issues, health issues, manufacturing and purchasing specifications, and policy positions taken by various stakeholders ranging from government to business to farmers.

The Most Common Bioplastics 

Polylactic Acid (PLA)

Polylactic acid or polylactide (PLA) is a bio-based plastic (a biopolyester, in particular) made from lactic acid, a fermentation product of corn or cane sugars. When two lactic acid molecules are combined they create lactide which forms the polymer backbone of PLA. Corn is most commonly used as the raw feedstock source for PLA. (Tolinski, p.106) 

Most PLA consumer products are made using Ingeo, a branded PLA produced by Natureworks LLC, which is jointly owned by agri-food behemoth Cargill and PTT Global Chemical. 

Products made with Ingeo PLA can include clothing, bottles, gift and credit cards, bags, food packaging, fabrics, fibre fill for pillows and comforters, diapers, wipes, disposable dishes.  

Ingeo PLA is certified compostable (i.e., fully biodegradable) in an industrial composting facility by various third party certification bodies, including BPI, DIN CERTCO, and JBPA. It is not biodegradable in home composters, plain soil or a marine environment.  

Most Ingeo PLA appears to be made at least in part from genetically-modified (GM) corn, which is a key corn source in North America. Natureworks does offer its customers three different source option programs to limit or offset the amount of GM corn in the PLA they produce, but Cargill is the world's largest producer of GM corn, and the reality is that most PLA made in North America is made from GM corn. Cargill's environmental track record is not good, and the GM corn has been shown to have unintended negative health and environmental effects.

Be sure to check the label on any PLA product to ensure the whole product is certified compostable because other non-biodegradable ingredients may have been added during the manufacturing of the product - in which case the product is not fully biodegradable.

Polyhydroxyalkanoates (PHAs)

Polyhydroxyalkanoates (PHAs) are a family of bio-based plastics (biopolyesters, in particular) created from sugar through fermentation processes that take place inside certain naturally-occurring bacteria; these same bacteria can also degrade and consume PHA products upon disposal. (Tolinski, p.110-111) 

They are used to make such products as films and bags, carpeting, some clothing, shampoo bottles and other disposable personal care products. They are also used in medical implants, tissue engineering, and drug delivery. But the cost of producing PHA is high enough to limit its widespread use.

The main company making PHA biopolymers for consumer products is Metabolix, and its two main biopolymer branded products are:  Mirel (for rigid applications; certified home, soil and freswater biodegradable by Vinçotte) and Mvera (for films and bags; certified compostable in an industrial facility by Vinçotte). Metabolix also claims Mirel is marine water biodegradable though there is currently no third party certifier for that.

Be sure to check the label on any PHA product to ensure the whole product is certified compostable because other non-biodegradable ingredients may have been added during the manufacturing of the product - in which case the product is not fully biodegradable.

Starch-based Biopolymers

Starches are glucose-based, energy-rich carbohydrates stored in plant cells. Some common sources for bioplastic purposes include corn, wheat, and potatoes.

One of the most common starch-based bioplastics is a form of Mater-Bi bioplastic, which is made by the Italian compnay Novamont.  It is made from various non-GM sources of starch and contains other vegetable ingredients such as cellulose, glycerin and natural fillers. There are also non-starch-based grades of Mater-Bi, which contain non-starch renewable raw materials and fossil fuel-derived raw materials. 

Mater-Bi is used primarily to make films and bags. For example, it is the biopolymer source material for Biobags (Canada / US).

Mater-Bi is third party certified to be biodegradable and compostable by BPI, DIN CERTCO, Vinçotte, and the Italian CIC-Certiquality.

Once again, be sure to check the label of such products given the varied grades of Mater-Bi - some may not carry all the certifications for biodegradibility and compostability.

Oxo-Biodegradable Plastics

Oxo-biodegradable plastics are traditional fossil-fuel based plastics that have been combined with metal salts or other additives to make them break down faster (e.g., the BioPVC described above). They are included in the bioplastics category and are often touted by the industry - especially the Oxo-Biodegradable Plastics Association - as biodegradable, but whether they really break down completely in the natural environment in the time frames quoted is questioned by experts.

They are commonly used, for example, to make polyethylene-based plastic bags, which are an enormous environmental pollution problem. 

Based on her research, Beth Terry has the following to say about some of the "degradable additives" used to make such "bioplastics":

Symphony's D2W, EPI's TDPA, and GP Plastics Corporation's PolyGreen are oxo-biodegradable additives - they contain a heavy metal that causes the plastic to start breaking down mechanically. Earth Nuture Additive (ENA), ENSO Bottles, Bio-Tec's EcoPure, and ECM Biofilm's additives, on the other hand, are meant to attract enough microbes to the plastic to break it down. None of these additives has received third-party certification because none has proven it will biodegrade within the time frame specified by the standards. What's more, the Association of Postconumer Plastic recyclers is concerned that degradable additives may shorten the useful life of plasitcs and hinider their ability to be recycled. 

Bagasse

Bagasse is the fiber left over after sugarcane or sorghum are crushed to extract their juice. It a bio-based product, but not a bioplastic. It's more of a paper product. As Beth Terry indicates in her book, the BPI database lists manufacturers of molded products from other types of natural fibers, including wheat, bulrush, bamboo, and palm. 

We mention it here because it is becoming more common as a material for compostable food containers. The fibre is pulped and can then be molded into various shapes.  For example, Green Century Enterprises makes clamshell food containers and trays from sugarcane bagasse and reed fiber, and which are biodegradable, compostable and organic and certified by BPI. You want to be sure a bagasse product is certified compostable, because some have a plastic coating.

  

Key references used to write this section:

  • Anthony L. Andrady, ed. Plastics and the Environment. Hoboken, NJ: John Wiley & Sons, 2003.
  • Susan Freinkel. Plastic: A Toxic Love Story. New York: Houghton Mifflin Harcourt, 2011.
  • E.S. Stevens. Green Plastics: An Introduction to the New Science of Biodegradeable Plastics. Princeton: Princeton University Press, 2002.
  • Beth Terry. Plastic Free: How I Kicked the Plastic Habit and How You Can Too. New York: Skyhorse Publishing, 2012. (Beth's Bioplastics section was especially helpful and time-saving in preparing the above overview of bioplastics.)
  • R. C. Thompson, C. J. Moore, F. S. vom Saal and S. H. Swan, eds. "Theme Issue: Plastics, The Environment and Human Health." Philosophical Transactions of the Royal Society B. Vol. 364, No. 1526, 27 July 2009.
  • Michael Tolinski. Plastics and Sustainability: Towards a Peaceful Coexistence between Bio-based and Fossil Fuel-based Plastics. Salem, MA: Scrivener Publishing, 2012.