A plastic shopping bag used by many retailers

There are now laws all over the world - from China to Bangladesh to Ireland - banning, restricting or taxing plastic shopping bags. In the United States, San Francisco, California, in March became the first American city to ban non-biodegradable plastic bags.

Sunset Scavenger dump is home to the waste of some 820,000 San Francisco residents. Waste that is made up of hundreds of plastic bags. They are cheap to produce, but hard to recycle, and they often end up in places they should not be, says Robert Reed, spokesman for Sunset Scavenger Waste.

"They're very lightweight. They blow into marshes, and onto farms. They wind up in the Bay, and in the current, and they wind up out in the ocean. They are a threat to marine life," Reed said.

These hazards, and the fact that the city was trashing roughly 180 million plastic bags a year, are what prompted San Francisco Supervisor Ross Mirkarimi to write a bill banning plastic carrier bags from all major chain supermarkets and pharmacies. But he hopes the law will inspire people to do more than that.

"The ban is also not just about not using plastic bags," Mirkarimi said. "But it's about not using paper as well, so that the goal and the thrust would be: hey, use neither paper nor plastic, bring your own."

'Bringing your own' is a concept shopper Sabina Talia-Ferro was already familiar with. 

"In Holland, they never give you a bag, you have to bring your own bags, so I was accustomed to that already," she said.

Other shoppers have happily cooperated with the ban.  

Grocers too. Store owner Sam Mogannam says he now pays 10 times more to provide paper bags to customers than he did with plastic. 

"The only impact was the increase in cost, and it wasn't a cost we were opposed to taking," he said.

Not all grocers feel that way. The California Grocers Association, which represents about 500 members, does not support the ban, says spokesman Dave Heylen. 

"The intention of the ordinance was to move consumers away from bags and to begin to have them look at alternative ways of shopping," he said. "But we don't think that this accomplishes that all that it has done is that consumers have just shifted from a plastic bag to a paper bag."

The next step? To extend the ban to small grocers and retailers. Supervisor Mirkarimi also says he's working on a bill to ban plastic bags on newspapers.