inFact with Brian Dunning inFact with Brian Dunning

 

The Trashy Secret of Plastic Bag Bans

Science shows that those plastic bag bans you love so much may be doing the environment more harm than good.

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We all love our bans on the single-use plastic shopping bags. Banning them reduces litter, and it also saves us making so much plastic -- and making plastic requires oil. And that's all great, right?

Wrong! We've been testing these bans all around the world for a long time now, and it turns out that almost everything we hoped to accomplish either backfired or was never a real problem to begin with.

Myth #1: Plastic carryout bags contribute to ocean plastics

Turns out this is only the case in China and other developing nations where they mismanage up to 76% of their trash, meaning it ends up as litter. But in the United States, we mismanage less than 2% of our trash. It's ugly when we see it in population centers, but our rivers and environment are among the cleanest of populated areas in the world. Less than 1% of ocean plastic comes from the United States, and our plastic bags are less than 1% of that.

There are problems with consumer behavior in the United States, but plastic bags just aren't very high on that list. They're just visible and easy to make laws about, but it's not really accomplishing anything except making people feel good.

Myth #2: Bans decrease the amount of disposable plastic leaving the supermarket

This is actually true but it's only by the slimmest of margins. Turns out a lot of plastic bags get reused around the house. And when we no longer get them free at checkout, we end up buying the ones we need. We found that where bans have been put in place, sales of 8-gallon bags went up 64%, and sales of 4-gallon bags more than doubled, rising by 120%! And moreover, the ones we buy are a lot heavier and contain a lot more plastic than the free ones.

Myth #3: Plastic bags are worse for the environment than other options

There are other options. Paper bags, durable reusable plastic bags, and reusable cotton bags. So we look at the overall life cycle of all of these products, covering sourcing of the raw materials, manufacturing costs and impacts, use phase, and then the end of life which might mean recycling costs or landfill costs or even incineration.

Turns out the single-use plastic bag has BY FAR the lowest carbon footprint. Paper bags are 4 times worse; durable plastics 14 times worse, and studies show almost nobody reuses them 14 times; cotton bags are 173 times worse, and again studies found that almost none of them actually last and are kept for 173 supermarket trips.

So the bottom line: If bans are so bad, what SHOULD we do? Economists already have the answer.

    1. Keep the flimsy single-use bags available as before, but charge a small fee for them like 10 cents to encourage people to keep their durable reusables around longer.

    2. Stop offering the cotton reusable bags.

    3. Continue development of plastics based on lower-impact petrochemical alternatives.

— Brian Dunning

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References & Further Reading

Bisinella, V., Albizzati, P., Astrup, T., Damgaard, A. Life Cycle Assessment of grocery carrier bags. Copenhagen: Ministry of Environment and Food of Denmark, 2018.

Edwards, C., Fry, J. Life Cycle Assessment of Supermarket Carrier Bags: A Review of the Bags Available in 2006. Bristol: UK Environment Agency, 2006.

Jambeck, J., Geyer, R., Wilcox, C., Siegler, T., Perryman, M., Andrady, A., Narayan, R., Law, K. "Plastic waste inputs from land into the ocean." Science. 13 Feb. 2015, Volume 347, Issue 6223: 768-771.

Mattila, T., Kujanpää, M., Dahlbo, H., Soukka, R., Myllymaa, T. "Uncertainty and Sensitivity in the Carbon Footprint of Shopping Bags." Journal of Industrial Ecology. 1 Mar. 2011, Volume 15, Number 2.

Rosalsky, G. "Are Plastic Bag Bans Garbage?" Planet Money. National Public Radio, 9 Apr. 2019. Web. 13 Jan. 2020. <https://www.npr.org/sections/money/2019/04/09/711181385/are-plastic-bag-bans-garbage>

Taylor, R. "Bag leakage: The effect of disposable carryout bag regulations on unregulated bags." Journal of Environmental Economics and Management. 1 Jan. 2019, Volume 93: 254-271.

Taylor, R., Villas-Boas, S. "Bans vs. Fees: Disposable Carryout Bag Policies and Bag Usage." Applied Economic Perspectives and Policy. 27 Sep. 2015, Volume 38, Issue 2: 351-372.

 

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