Ask Pablo: Are Plastic Bags Better After All?

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Dear Pablo: Is it true that plastic bags have less impact on the environment than the alternatives?

The findings of an unpublished UK government research report, obtained by Independent on Sunday and covered by TreeHugger's own Sami Grover, should come as no surprise. But still, most people would be shocked to learn that the canvas bags that they have been toting around may actually have a higher environmental impact than the plastic bags that we all vilify.

Frequency Of Reuse Matters
As with so many environmental questions in which you try to compare a conventional product with a "green" alternative, the answer is complicated. In the past I have been asked about coffee mugs, plates, cutlery, and (of course) bottled water. In this case we are comparing a disposable product (the plastic bag) to a durable product (the cotton tote bag).

According to the report, the canvas bag needs to be used 171 times to have the same global warming intensity as a single-use HDPE bag (1.57 kg CO2-equivalents). The key here is that a reusable canvas tote bag needs to be used more than 171 times to break even with the environmental impact of plastic bags.

It's About More Than Just Greenhouse Gas Emissions


Of course it is false to equate greenhouse gas emissions alone to environmental impact. As James Murray points out on James' Blog the report "does not even take account of litter and other environmental impacts." It is these impacts that are behind the growing number of plastic bag bans in cities across the US and the world. By focusing only on greenhouse gas emissions this report may lead readers to believe that plastic bags are actually better.

The truth is that plastic bags are made from a non-renewable resource and are rarely recycled (only 1-3% of plastic bags and 10-15% of paper bags are recycled). If plastic bags don't end up in the landfill they often find their way into waterways and oceans, where they break down into tiny particles that can harm aquatic life but they will never degrade completely.

So What Is The Right Decision?
Many reusable shopping bags today are made from organically grown materials or are made from recycled plastics. A reusable recycled plastic shopping tote made from polypropylene or a polyester Chicobag must only be used 10-20 times to break even with the disposable plastic bag. For more information on choosing a reusable shopping bag READ THIS.

What ultimately matters is if you actually use your disposable bags, or if you collect them dutifully from vendors and at conferences but then forget them at home every time you go to the store. If you can commit to using your canvas bag 171 times, or something like a Chicobag eleven times or more, then you have made a good decision. If you can't commit to this, chose plastic over paper bags, reuse the bags at the store, repurpose them as trash can liners, and recycle the rest at your local grocery store.