In Defense of the Plastic Bag

Pity the much-maligned plastic bag.

Plastic bags are being banned or taxed in cities and counties across America–just this week in Seattle, before that in San Francisco, Portland and Washington, D.C. Beginning in January, Montgomery County, MD, where I live, will impose a five-cent charge for carryout bags at all retail stores. Like most of my neighbors (median household income in the county tops $92,000) I can afford the extra nickel.

But I’m not persuaded that plastic bag bans or taxes makes sense. Here’s why.

They’re not based on science. Independent studies show that plastic bags are environmentally preferable to paper. Others suggest that, when they are reused, they are preferable to the reusable plastic or cloth sacks that many of us tote around.

Some of the arguments put forth for the bans don’t hold up. That plastic waste waste in the oceans you’ve probably read about? No, it’s not the size of Texas. Nor is it made of plastic bags.

Getting rid of carryout bags won’t lead to a long-term solution to the problem of plastic waste. Maybe instead of banning or taxing bags, we should be recycling them. That’s the argument being put forth by a company called Hilex Poly, which will recycle tens of millions of pounds of plastic bags, sacks and wraps this year, and would like to do more.

You may disagree but after digging into this subject for a while, I’m certain about only one thing: It’s complicated.

The arguments for plastic bag bans or taxes are, by now, familiar. The Montgomery County carryout bag law “is designed to improve our environment by cutting down plastic bags—a significant source of litter—which pollute our streets, streams, and playgrounds, and harm property values.” Econ 101 tells you that charging 5 cents for plastic bags creates an incentive for people to use fewer of them, and carry reusable bags instead. Proceeds go to “programs that fight litter and provide stormwater pollution control.”

Bill Hickman, who leads the Rise Above Plastics campaign at the Surfrider Foundation, an advocacy group, told me by phone: “We’re trying to stop the plastic impact on the marine environment. Plastic doesn’t biodegrade in our lifetime…Anything, single use, at the end of the day has negative effects on our environment.”

All true, but…

Studies say that plastic bags have a lighter environmental footprint than paper, and in some cases are preferable to reusable bags. A thorough life cycle analysis done in the UK by the government’s environment agency in 2006 (download PDF here) found that HDPE (high-density polyethylene, the typical lightweight plastic bags) are superior to paper because they require less energy and far less water to make and take up less space in landfill. Comparing them to reusable non woven polypropylene (PP) bags–the typical reusable bag, made in China, and sold by grocers–the study found that their impacts depend upon the number of times that plastic bags are reused. Data on this is scarce and controversial–critics of plastic say the bags are typically used just once, but the industry says they are frequently used, often as garbage bags, or to carry kids’ lunches to school, or pick up dog poop. (Banning plastic carryout bags means that people may have to buy bags for those purposes.) Focusing on the climate issue, the 120-page-long UK study says:

The paper, LDPE, non-woven PP and cotton bags should be reused at least 3, 4, 11 and 131 times respectively to ensure that they have lower global warming potential than conventional HDPE carrier bags that are not reused.

If I understand that correctly, it means that one reusable bag has the carbon footprint of 13 disposable bags that are used just once. If you use the disposable bag twice, you’ll need to deploy the reusable bag 26 times before you are ahead in terms of global warming. By the way, this doesn’t include the impact of washing the reusable bag in hot water, which is highly recommended because bacteria like E. coli and fecal coliform can thrive in reusable bags, according to this study, which, it must be said, was financed by the plastics industry.

A study from the University of California, Chico, funded by Keep California Beautiful, analyzed the U.K. studies, as well as research from Scotland, Australia and a U.S. consulting firm and found that “reusable plastic bags can have lower environmental impacts than single-use polyethylene plastic grocery bags.” But it also found traces of cadmium and lead in the reusable bags. The professor who did the study has consulted for both plastic bag and reusable bag makers. Like I said, it’s complicated.

Next Page: Exactly how bad is the plastic pollution in the ocean?