The results of the first-ever broad-based scientific study on the environmental effects of plastic bags have proved surprising and embarrassing.

Just when the world’s supermarket chains seem to have united against handing out free plastic bags a till points, a study by Greenpeace has revealed that the bags, often thought of as “the most visible symbols of environmental waste”, have had very little environmental impact.

“Our new study has shown that very few marine animals are being killed by plastic bags and the bags themselves have only a small environmental impact compared to that of other forms of plastic,” says Dr David Santillo of Greenpeace in yesterday’s report.

It seems like series of blunders in the early 2000s gave plastic shopping bags an unfair trial. Just a single dramatic phrase “100,000 marine animals and millions of sea birds are estimated to be killed by plastic bags each year” drove supermarkets into a misguided environmental myopia.

By 2006 it had become clear that the original study on which this statement was based in fact referred to the impact of ‘fishing nets’ and not ‘plastic bags’.

“Supermarket chains were too ready to embrace ‘sexed up’ facts, dubious science and poor business judgment,” says the Greenpeace report.

Wal-Mart and Tesco have been quick to defend their positions but the Greenpeace report puts the blame squarely on the kind of short-sighted business judgment that usually results in environmental degradation.

It seems that Greenpeace’s enemy is still big business, but this time they are accused of using misinformation that Greenpeace itself had been instrumental in distributing.

Has Greenpeace itself finally become another example of ‘big business’?