January 9, 2014

Steven Stein likes to trail garbage trucks. “As long as my girlfriend’s not with me, I follow them,” the Maryland resident says. “It’s hard to resist.” Stein’s odd habit makes sense when you consider that he’s an environmental scientist who studies how to reduce litter, including stuff that falls off garbage trucks as they barrel down the road. What is even more interesting is that one of Stein’s current gigs is defending an industry behind a notorious source of trash: the disposable plastic shopping bag.

Americans use more than 100 billion thin film plastic bags every year. So many end up tangled in tree branches or strewn along highways that a growing number of cities are banishing them from checkout lines. The bags are outlawed in some 90 municipalities in California, including Los Angeles, where a ban took effect this month. In 2013, Santa Fe, N.M., and Olympia, Wash., passed bans, and even Dallas, a city not given to stringent regulation, took up the issue.

Eyeing these headwinds, plastic-bag manufacturers are hiring scientists like Stein to make the case that their products are not as bad for the planet as most people assume. “It’s important to base your decisions on facts,” says Stan Bikulege, CEO of Hilex Poly, which has hired Stein. (If persuasion fails, the industry has been known to sue cities that pass plastic-bag bans.)

Among the bag makers’ arguments: many cities with bans still allow shoppers to purchase paper bags, which are easily recycled but require more energy to produce and transport. And while discarded plastic bags may be ugly to look at, they represent a small percentage of all garbage on the ground today.

The industry has also taken aim at the product that has emerged as its replacement: reusable shopping bags. The sturdier a reusable bag is, the longer its life and the more plastic-bag use it cancels out. But this formula has a flip side. Longer-lasting reusable bags often require more energy to make. One study found that a cotton tote must be used at least 131 times to be better for the planet than plastic.

Environmentalists don’t dispute these points. They hope paper sacks will be banned someday too and want shoppers to use the same reusable bags for years. So are reusables our destiny? Yes, unless you plan to go to the store a lot. Andy Keller, inventor of the reusable polyester ChicoBag, says, “If you can carry it out in your hand or put it back in your cart, you don’t need a bag.”

–KATE PICKERT

This appears in the January 20, 2014 issue of TIME.

Contact us at editors@time.com.

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