Which is more sustainable: Paper Bags or LDPE Bags?

Question

At the grocery store, many offer a choice between brown paper bags (often doubled) or Low Density Poly-Ethylene (LDPE) plastic bags.

If you plan to recycle in either case, which solution is more sustainable?

Alternatively, is buying a reusable heavy duty plastic coated bag better than these disposable choices, or how about a reusable canvas bag? Another option (only seen this at Food Co-Ops) is reusing the boxes that the store received to package the goods coming in.

If you had to prioritize all these choices, is there a clear ranking and ordering among them?

Answer 1

In priority order:

1. Durable canvas bag. This will last years and can be reused many times. When the bag finally reaches the end of its life, after you've handed it down to your grandchildren, they can compost it. Just remember to always take them with you...
2. The cardboard boxes they offer you at the store, if available, and you've forgotten your canvas bags. Corrugated cardboard can be reused -- it would be bulky to carry back to the store, but you may find uses for it around the house. Cardboard is also recyclable, can be used as the bottom layer of a sheet mulch (i.e. composted), and can be torn into decent kindling for starting fires in a wood boiler/furnace.
3. Paper bags offered at the checkout, when you forget your bags and there are no boxes available. If you're careful, these can be reused once or twice, are recyclable, come from renewable resources, can be composted, or even used as notepaper.
4. Durable plastic bags aren't something I'd choose, but if you have them, you might as well reuse them as much as possible. They aren't as recyclable, aren't created from renewable resources, and don't generally break down in the environment. (Though I suppose you could get vegetable-derived plastic, you'd probably be better off just using paper or canvas.)
5. Disposable plastic bags seem like a clear loser. They fall apart fast so you can't really get much reuse from them, they don't usually end up getting recycled, and they last just about forever in the environment.

Answer 2

Only 5.7% of LDPE is recycled. Most of it ends up in the environment. Biodegradation time is 500-1000 years if exposed to light, else decomposing time is infinite. Go for a paper bag.

If you really plan to recycle it: paper bags will be new paper bags, LDPE bags will be clothes or carpets in asian or african markets. Paper can be recycled as often as you want to (as long as it does not get contaminated too much), LDPE can only be recycled once. Go for a paper bag.

Don't buy re-usable plastic bags. Read more about why not plastic in this question: Which plastics should I avoid and what qualities of plastics are important to consider?

In short, buy re-usable organic cotton or organic hemp bags and you are happy for years with them... the environment, too.