Plastic Bags: Bio-digestion, Bans and the Green Fee

There's a new buzz in the seemingly endless shopping bag debate. A 16-year-old Canadian high school student, puzzled that society was full of gripes about plastic bags but short on solutions, set out to find a biological means of breaking down the nuisance shopping sacks.

Daniel Burd of Waterloo, working out of his home with common materials like yeast and tap water, succeeded in isolating two strains of bacteria that together appear to be capable of digesting plastic bags over time, under specific conditions. After a series of experiments, he isolated the primary plastic consumer, Sphingomonas and a helper bacteria, Pseudomonas (Burd's theory is that the latter helps the former reproduce). He then combined the two in flasks, along with water, strips of plastic grocery bags and sodium acetate (which provides carbon to fuel bacterial growth) at 37 degrees.

The result: Six weeks later, 43% of the plastic had degraded. Burd guessed it would be entirely gone within six more. (Read the full article from The

The process takes time, but compared to the 1,000-plus-year lifespan of plastic bags in landfills, three months seems extremely do-able.

Of course, the solution solves the problem from the back end—the waste stream--rather than from its source. While plastic bags polluting our land and water are problematic, the destruction begins with the extraction of oil to produce the bags in the first place. Which is why societies willing to forgo the bags altogether stand to gain more than just bag-free landscapes: China's ban on thin plastic bags, according to estimates, could save the nation 37 million barrels of oil. At the current rate of about $128 per barrel, that's more than $4.7 billion.

Burd's accomplishment is a great one. Hopefully, further testing will allow us a deeper understanding of the potential for bio-digestion as a means to help rid our land and seas of plastic waste (and also of the limitations, because obviously introducing bacteria into an ecosystem, even with good intentions, will have an impact). But bigger solutions are those that curb our need for plastic bags before they're even created.

Seattle City Council President Richard Conlin and Mayor Nickels have proposed a 20-cent fee on all disposable shopping bags (paper and plastic). If passed, the policy has the potential to reduce plastic bag use to a trickle (a 15-cent plastic bag tax adopted in Ireland in 2002 decreased plastic bag use by more than 90% ). The Seattle bill also includes a ban on Styrofoam packaging in all restaurants.

An argument rages in the local media over this issue, but we urge you to think carefully. Eliminating disposable bags is not the most impactful action we can take in the face of climate change (see this Sightline study to see why the groceries in your bag far outweigh your carrier of choice in terms of greenhouse gas emission). But it is one significant step in the right direction: Rather than simply encouraging one shopper at a time to switch to cloth bags, it takes a systemic approach to create change in consumption and waste on a citywide level. At Worldchanging, we'd like to see Seattle show the rest of the country that we can handle the relatively small challenge of changing our shopping habits…and then we can think about putting Burd's bacterial findings to work on what's left over.

Photo courtesy of flickr/WYGD. Licensed by Creative Commons.