The Folly of Plastic Bags

“Paper or Plastic?”  Such a familiar question, and yet how many people stop to consider the environmental impact of utilizing such a common product as a plastic bag?  To understand the extent of their impact upon the planet, it is important to understand the process by which they are made.

Plastic bags are typically made from oil, and are a by-product of the oil-refining process.  Electricity constitutes the biggest energy input in the plastic bag creation process, which normally comes from coal-burning power plants at least 50% of the time. Electricity heats the oil so that it can be separated into various components and then molded into polymers. Plastic bags most often come from polyethylene in its low-density form (LDPE), also known as #4 plastic.  The good news about #4 plastic is that it can be recycled, but the process isn’t simple or easy. Recycling essentially involves repeated the above process, although manufacturing the recycled plastic requires two-thirds of the energy used in virgin plastic manufacturing. The trade-ff is that the end product is a lower-quality plastic and is not suitable for use in some products.  This phenomenon is called “downcycling” where it loses its viability and functionality as a raw material through the process of recycling.

What about biodegradable plastic bags?

Biodegradable plastic is a mixof polyhydroxyalkanoate (PHA) and Polylactide (PLA), which are completely biodegradable in compost, but not nearly as earth-friendly as you’d think when they’re in a landfill.  Bioplastics are made primarily from corn, and are thus not a complete solution to petroleum-based plastics, because corn is rife with agro-political conflict and often grown and harvested unsustainably.

Some bags marked “biodegradable” are not actually so — they’re a mix of recycled plastic and cornstarch. The cornstarch biodegrades and the plastic breaks down into tiny little pieces but does not actually “biodegrade,” leaving a nasty mess that contributes to the Great Pacific Garbage Patch and damages the environment.

The best alternative?  Don’t use plastic bags at all.  Canvas bags are sturdy, have a much greater carrying capacity than those thin bags from the grocery store, and they’re 100% reusable.