Paper or plastic — what’s the greener choice?

Would you like paper or plastic? It's the question food shoppers are asked every day — a simple choice that even environmentally conscious shoppers at Whole Foods find confusing.
"I generally pick paper because it's more protective of the environment," one shopper tells us.
But all too often, convenience rules.
you caught me on a plastic day," another shopper says. "Now I feel guilty."But should she?
Consumers find themselves between a rock and a hard place when it comes to paper or plastic. To find out what is best to do in the grocery store, we turned to Allen Hershkowitz of the Natural Resources Defense Council.
"It depends on where you live," he says.
Plastic bags threaten wildlife along the coasts, so if that's where you call home, Hershkowitz says the choice should be paper. In the heartland, he says it's plastic.
"I just assumed paper was the better choice — more environmentally friendly choice," our guilty shopper says.
But people don't realize how big a footprint the paper industry has.
Here's how paper and plastic stack up side by side:
To make all the bags we use each year, it takes 14 million trees for paper and 12 million barrels of oil for plastic. The production of paper bags creates 70 percent more air pollution than plastic, but plastic bags create four times the solid waste — enough to fill the Empire State Building two and a half times. And they can last up to a thousand years.
Plastic, because it's cheaper to produce, is the overwhelming choice of grocery stores across the nation — the average family of four uses almost 1,500 of these a year. San Francisco is limiting consumers' freedom of choice, allowing only biodegradable plastic bags, which break down over months rather than hundreds of years.
For both types of bags, the environmentalist mantra is the same — reuse and recycle. But the best choice, they say, is cloth or canvas, and BYOB — bring your own bags.