The Bay's got a brand new bag

San Francisco’s Board of Supervisors passed an initiative in late March to phase out plastic bags in the city’s grocery stores over the next six months and in pharmacies over the next year. Although local media sources and environmental groups around the country praised the move, some critics have voiced concerns that one of the proposed alternatives — compostable plastic bags — are hardly an improvement.

According to the city’s Department of the Environment, grocery stores and pharmacies hand out 90 percent of plastic bags used in San Francisco. Under the new law, the stores will be allowed to use only recycled paper bags or compostable plastic bags that are certified by the American Society for Testing and Materials and verified by the Biodegradable Plastic Institute.

Reducing landfill waste and litter is a primary stated goal of the law. While some critics have voiced concerns that the compostable bags don’t break down, Jerry Bartlett of Seattle-based Cedar Grove Composting says certified compostable bags that have been through stringent simulation tests actually do compost in a commercial setting.

Still, Bartlett points out, even though San Francisco has curbside compost bins, not all grocery store and pharmacy customers compost the bags. If they don’t, the bags will go into landfills, and Bartlett says not all bags that are suitable for composting are designed to breakdown in landfill conditions. It remains to be seen what sorts of bags San Francisco grocery stores and pharmacies will purchase, but BioBags, manufactured by Norwegian company Polar Gruppen, are recommended by both Cedar Grove and the Biodegradable Plastic Institute.

The ban also aims to cut the use of petroleum. “As a polymer chemist, I love plastic,” says Mark Michalovic, consultant for educational services in the Roy Eddleman Institute for Interpretation and Education at the Chemical Heritage Foundation. “But while I appreciate that plastics are amazing materials, I also know they are made from a finite resource: petroleum.”

Michalovic says petroleum-based plastic should be saved for products that (unlike grocery bags) can’t be made with another material. The California Grocer’s Alliance and the Progressive Bag Alliance (PBA), a group of plastic bag manufacturers that advocates for plastic bag recycling, worked with the city to build up plastic bag recycling programs, says Andy Devilling, vice president of sales and marketing for PBA member Starpak.

Devilling says grocery stores could make money by recycling plastic bags, rather than spending money on compostable bags. While conventional plastic bags cost stores 2 to 3 cents on average, compostable bags can cost anywhere from 5 to 10 cents each. He cites the example of Wal-Mart (NYSE: WMT), which recycled 57 million pounds last year and picked up $10 million for its trouble.

Supervisor Ross Mirkarimi, who spearheaded the initiative, told the press local stores had not kept their promise to reduce plastic bag use and promote recycling, and consumers did not recycle enough bags.

The California Grocers Alliance and PBA claim lawmakers didn’t give recycling programs a chance. The groups say providing bags from compostable plastic will increase the cost of doing business in the city.

Another proposed solution to the bag problem is a bag tax, which San Francisco looked into in 2005. Some local retailers went ahead with the tax on their own — Ikea in nearby Emeryville, Calif., charges 5 cents (12 cents less than the 17 cents suggested by the Board of Supervisor’s 2005 proposal) per bag, and cashiers have noticed a marked decline in bag usage. Ireland passed a similar countrywide bag tax in 2002 and saw a near immediate decrease in use, eventually cutting the country’s use of plastic grocery bags by 90 percent.

Proponents of the tax argue it gets at the root of the problem more directly, by reducing bag use overall. Nadine Weil, vice president and CFO of Pathway Ventures, suggests going one step further and encouraging people through monetary incentives (bag credits) to bring their own canvas bags and to reuse their recycled paper shopping bags. She points to Whole Foods Markets [Nasdaq:WFMI] as a successful implementor of the tactic.

San Francisco already has infrastructure in place to handle compostable waste. Several other U.S. cities, including Los Angeles, Santa Cruz and Boston, are now considering similar bans.