Sustainable Mill Valley Member Cathy Rosekrans has written some guidelines in coordination with Green Sangha Marin.
Bioplastics – Caution Advised
The best alternative to single-use produce bags is no bag at all. If that isn’t possible, a reusable bag can come in handy. But what about the new bioplastic bags?
In this rapidly changing area, Green Sangha currently advises “caution.”
Government regulation over bioplastics is sparse. Voluntary collaborations (visit www.sustainablebiomaterials.org and www.greencitiescalifornia.org) are working to keep up with new developments, to sift valuable innovation with potential merit from mere greenwashing. Produce vendors may attempt to select among alternatives, but in an ever-changing environment, the “best” is very hard to discern. Not all bioplastics are created equal, and the careful consumer needs to know more about the bioplastic bags that they are using.
DEFINITIONS MATTER: IS THIS BAG REALLY COMPOSTABLE? Many consumers choose bioplastics because they want a compostable product that is not derived from fossil fuel. Whether a particular bag meets these criteria depends on what it is made of. In short, a truly compostable bioplastic bag should meet the standards set by ASTM (American Society of Tests and Measures) D6400. The Biodegradable Plastics Institute (BPI) will certify bags complying with ASTM 6400, if the manufacturer submits for certification. Look for the following BPI logo:
To clarify, here are key definitions:
- Degradable Bags: In terms of environmental protection, this designation is meaningless. Just about any bag is “degradable”. This means that it will eventually degrade in the right conditions (including chemical). “Eventually” could mean centuries! Degradable bags may be fossil fuel based.
- Biodegradable Bags: These bags must break down through the metabolism of naturally occurring microorganisms such as bacteria or fungi over a reasonable period of time. “Reasonable” can cover a wide range of time, even many years. Biodegradable bags may contain toxins.
- Compostable: These are what most people think of when we hear the term “biodegradable”. Compostable bags biodegrade relatively quickly, completely and safely (no known toxins) in a professionally managed municipal or industrial compost facility. (It may take longer in a home compost system depending on system variables). Look for BPI Certification to assure that the bag meets the ASTM D6400 test for compostability. Look for the BPI Logo (circle and leaf design above), or go to the BPI website (www.bpiworld.org), and look for the “Directory of Certified Compostable Products”. (If a bag is labeled “compostable”, but does not have a BPI label or other indication that it has passed ASTM standards, it may not be truly compostable).
BPI Certification is not a guarantee that unwelcome byproducts are absent from the product. For example, even with BPI Certification, a bag may be derived from crops containing genetically modified organisms (GMOs). Look for a bag that is both BPI certified and states that it does not use GMOs.
BIOPLASTICS DISPOSAL: WHERE DO THEY GO?
- RECYCLE? No! NEVER put bioplastics in with recycling! Any potential for batch recycling of other plastics is ruined by contamination with bio-plastics.
- COMPOST? Maybe! If you have a home compost pile or have a community compost program, bioplastics may be composted. How fast these will breakdown in home compost depends upon how frequently the pile is turned over, moisture, material content and temperature (“hot” compost is faster than “cold”). Community Composting is a growing phenomenon, bit is not universally available. There are few community-wide composting facilities in Marin TO DATE . There are pilot compost programs, with hopes of introducing full-scale composting (including curbside pickup) soon. TO DATE, Sonoma does not accept bioplastics for many reasons, mostly related to the rigors of meeting certified organic requirements. Other localities, such as San Francisco and many East Bay cities, accept bioplastics, many with a program to educate consumers on which bioplastic to purchase.
- LANDFILL? Without community or home composting, bioplastics go to landfill. In an airlocked landfill, no bag will decompose.
SO, SHOULD WE USE THEM?
Certified compostable bags have a few “end of life” advantages: If the purchaser has a compost pile or lives in an area with community compost, the bags have the distinct advantage of biodegrading. They also have some “beginning of life” advantages as they do not use fossil fuels as a materials base. Compared to paper, they are lighter, so use less energy in transport than paper (depending upon where the bags are coming from). .
But use bioplastics as a last resort. In some important environmental ways, they are worse than paper or plastic, including water consumption and methane generation. Many bioplastics are made from food sources, leaving less for the world’s hungry. Industrial agricultural practices for many crops are energy intensive, requiring petroleum to power farm machinery and irrigate growing crops, and to produce fertilizers, herbicides, and pesticides. The amount of energy used in continual manufacturing, production and transportation of throwaways is also a consideration. And, if bioplastics end up in cold oceans, not all will biodegrade.
Let’s get away from our throw-out mentality and enter an era of producer and consumer responsibility. When a bag is needed, choose a reusable.
Prepared by Cathy Rosekrans, March 18, 2010
Project Leader, Rethinking Plastics Campaign
Green Sangha (www.greensangha.org)
