The debate over banning plastic bags explained

Americans use an estimated 100 billion plastic bags every year. Although most plastic bags can be recycled, the vast majority of lightweight plastic bags end up in landfills or are set adrift in the environment, where they can wreak havoc on wildlife or infrastructure.

At least two Minnesota cities are exploring whether to ban businesses from handing out lightweight plastic bags for free. The Star Tribune reports that city officials in both Minneapolis and St. Louis Park are considering bans, which would be the first plastic bag bans in the state.

Bans or taxes on plastic bags are increasingly common across the world. But the policy measures have received some blowback from plastic bag manufacturers, who lobby the public and elected officials to oppose the measures.

Why ban plastic bags?

Opponents have a number of criticisms about plastic bags, ranging from complaints that bags hanging in trees mar the landscape to concerns that plastic bags are killing aquatic life.

The plastics industry argues that plastic bags are being demonized, and they challenge almost every fact cited by supporters of bans, although, to be fair, both sides in the debate often cite difficult to verify statistics.

Opponents say the fossil fuel-based bags are a waste of polluting and non-renewable resources. The industry correctly points out that plastic bags create less of a carbon footprint than the production of single-use paper bags, although it's not clear that people in areas with plastic bag bans or taxes automatically substitute paper bags

But there are other environmental concerns about plastic bags. Estimates of the time necessary for a plastic bag to degrade in a landfill range from 500 to 1,000 years, although there's no exact consensus among scientists.

They also account for a significant proportion of the trash in bodies of water, according to a United Nations Environment Programme report released in 2009. The bags accounted for about 8.5 percent of trash found in the Mediterranean Sea, and were commonly found on other beaches and in bodies of water studied by the agency.

The U.S. Environmental Protection Agency notes that marine animals can be harmed after eating or being tangled in plastic bags. Animals that eat plastic can starve, choke or be otherwise injured. A 2001 study of sea turtles cited by the agency found that 68 percent of them had eaten some sort of plastic, including plastic bags.

Windblown plastic bags that litter the streets, get tangled in trees or eaten by animals are also a problem in some areas. Some communities have banned the bags after they interfered with water infrastructure equipment. Bangladesh banned lightweight plastic bags in 2002 after it was found that they'd clogged drainage systems and contributed to widespread flooding in 1998 and 1988.

How effective have bag bans or taxes been?

Plastic bag bans or taxes are common in Europe and other parts of the world. Countries like Ireland, Eritrea and Taiwan either ban distribution of lightweight plastic bags or tax them.

The Irish tax on plastic bags has been one of the most high-profile examples. It appears to have resulted in a more than 90 percent decline in the number of plastic bags entering the waste stream and reduced the amount of litter on the streets. The Irish government estimates that the tax has led to a drop from 328 bags per person in the year when the levy was introduced to 14 bags per person in 2012.

There has been recent movement in the United States to ban or tax plastic bags. About 200 cities and counties in the United States, mostly in California, are covered by ordinances banning or taxing plastic bags, according to the environmental group Californians Against Waste.

The first statewide ban on plastic bags was passed in California last year but industry opponents have delayed implementation of the law by gathering signatures for a statewide referendum to be held in 2016.

If they're recyclable, why can't I recycle them?

Although many lightweight plastic bags are conceivably recyclable, they are not widely recycled because they can clog sorting machinery.

About 70 percent of city-run recycling programs in Minnesota do not recycle plastic bags, the Minnesota Pollution Control Agency found in a report published in 2013. Even the recently launched single-sort recycling program in Minneapolis doesn't accept plastic bags because of their tendency to gum up machinery.

Between 2000 and 2013, the amount of plastic in the statewide waste stream increased from 11.4 percent of 17.9 percent. Plastic bags — along with wrappers and shrink wrap — accounted for about 192,600 tons of statewide trash in 2013, according to the Minnesota Pollution Control Agency. The state agency has identified plastic bags and similar products as one area where recycling rates could be increased.