Saturday, March 08, 2008

Getting it right on plastic bags

You may live in a city that has decided to tax plastic bags. You know those flimsy opaque things with the grocery store logo on it. Or, they're planning on banning plastic bags outright.

Plastic bags have their problems, but be careful of the arguments used by governments to implement a tax on bags. Most of them have it wrong. In Britain, the government is getting raked over by the scientific community for basing their decision on an exemplary display of bad science.
Scientists and environmentalists have attacked a global campaign to ban plastic bags which they say is based on flawed science and exaggerated claims.

The widely stated accusation that the bags kill 100,000 animals and a million seabirds every year are false, experts have told The Times. They pose only a minimal threat to most marine species, including seals, whales, dolphins and seabirds.

Gordon Brown announced last month that he would force supermarkets to charge for the bags, saying that they were “one of the most visible symbols of environmental waste”. Retailers and some pressure groups, including the Campaign to Protect Rural England, threw their support behind him.

But scientists, politicians and marine experts attacked the Government for joining a “bandwagon” based on poor science.

Lord Taverne, the chairman of Sense about Science, said: “The Government is irresponsible to jump on a bandwagon that has no base in scientific evidence. This is one of many examples where you get bad science leading to bad decisions which are counter-productive. Attacking plastic bags makes people feel good but it doesn’t achieve anything.”

The whole premise that plastic bags are killing marine life is based on a misread and often misquoted line from a Canadian study.

The central claim of campaigners is that the bags kill more than 100,000 marine mammals and one million seabirds every year. However, this figure is based on a misinterpretation of a 1987 Canadian study in Newfoundland, which found that, between 1981 and 1984, more than 100,000 marine mammals, including birds, were killed by discarded nets. The Canadian study did not mention plastic bags.

Fifteen years later in 2002, when the Australian Government commissioned a report into the effects of plastic bags, its authors misquoted the Newfoundland study, mistakenly attributing the deaths to “plastic bags”.

The figure was latched on to by conservationists as proof that the bags were killers. For four years the “typo” remained uncorrected. It was only in 2006 that the authors altered the report, replacing “plastic bags” with “plastic debris”. But they admitted: “The actual numbers of animals killed annually by plastic bag litter is nearly impossible to determine.”

In a postscript to the correction they admitted that the original Canadian study had referred to fishing tackle, not plastic debris, as the threat to the marine environment.

Some of the heavy hitters in the environmental movement aren't happy with the British government's decision either. While they would probably like to see plastic bags eliminated, they would also like any ban or tax to be based on factual, not faulty, information and research.

David Santillo, a marine biologist at Greenpeace, told The Times that bad science was undermining the Government’s case for banning the bags. “It’s very unlikely that many animals are killed by plastic bags,” he said. “The evidence shows just the opposite. We are not going to solve the problem of waste by focusing on plastic bags.

“It doesn’t do the Government’s case any favours if you’ve got statements being made that aren’t supported by the scientific literature that’s out there. With larger mammals it’s fishing gear that’s the big problem. On a global basis plastic bags aren’t an issue. It would be great if statements like these weren’t made.”

There have been various studies on the effects of plastic debris in the marine environment and, like this one, none of them single out plastic bags as definitive problem.

Marine pollution by plastics has been shown to be damaging to marine mammals, birds and reptiles. This is due to entanglement in packaging bands, synthetic ropes and lines, or drift nets; or by the ingestion of small items of plastics debris.
The truth is, on the face of it, plastic bags have gotten a bad reputation for the wrong reasons. Most of those reasons have to do with litter and that is not caused by the bags themselves. Every time a plastic bag is simply dumped in a ditch, there is a human behind it.

South Africa has a problem with thousands of white plastic bags blowing around the rural areas. They are so prevalent that they are now referred to as a "national flower".

There is also a huge misconception about the impact of plastic bags on other elements of the environment, particularly when compared against paper shopping bags. Aside from the fact that they are made from a non-renewable resource (petroleum), they have a smaller carbon footprint than paper.

The US Environmental Protection Agency provides a good comparison between the two types of bags and nasty plastic comes out looking better than its paper cousin.

Paper sacks generate 70 percent more air and 50 times more water pollutants than plastic bags. (By Ed: Due to mill processing requirements. This is worse in some areas where, in Howe Sound British Columbia for instance, the mill has shifted to dirty coal from cleaner natural gas for fuel).

Paper bags are made from trees, which are a renewable resource. Most plastic bags are made from polyethylene, which is made from crude oil and natural gas, nonrenewable resources.

2000 plastic bags weigh 30 pounds, 2000 paper bags weigh 280 pounds. The latter takes up a lot more landfill space.

It takes 91 percent less energy to recycle a pound of plastic than it takes to recycle a pound of paper. It takes more than four times as much energy to manufacture a paper bag as it does to manufacture a plastic bag. Energy to produce the bags (in British thermal units): Safeway plastic bags: 594 BTU; Safeway paper bags: 2511 BTU.

Paper is accepted in most recycling programs while the recycling rate for plastic bags is very low. Research from 2000 shows 20 percent of paper bags were recycled, while one percent of plastic bags were recycled. (By Ed:Although most grocery stores accept plastic bags for recycling)

Current research demonstrates that paper in today's landfills does not degrade or break down at a substantially faster rate than plastic does. In fact, nothing completely degrades in modern landfills due to the lack of water, light, oxygen, and other important elements that are necessary for the degradation process to be completed.

Incineration can decrease the quantity of plastic and paper bags. However, incineration causes air pollution and creates ash which has to be landfilled.

As can be seen from above, the problem is disposal. The plastic bag is more likely to be used again as a garbage bag and end up in the landfill. The same use of paper bags (dubious for wet garbage) results in more space being taken in a landfill with no returned advantage.

In Ireland, where there is a tax on plastic grocery bags of 15 cents per bag, the use of plastic grocery bags has dropped sharply, however, Irish consumers have increased the use of plastic garbage bags purchased to line garbage cans by 400 percent.

Dilema! What to do? Use paper or plastic?


With the exception of the need to contain wet trash, a better idea is to acquire reusable shopping bags. In some grocery outlets, (not many yet), there is an incentive provided by removing a few cents from the final bill.

Developing a household strategy for waste control is more than just a little worthwhile. And while "disposable" grocery bags seem to be getting all the bad press lately, product packaging is a far worse problem.

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