CLAIMS that plastic bags are responsible for killing hundreds of thousands of animals every year have been dismissed by leading scientists and environmentalists.
The comments contradict efforts to stop supermarkets from handing out billions of the bags every year.
A senior spokesman for Greenpeace said: "It is unlikely that many animals are killed by plastic bags. The evidence shows just the opposite."
Already, the Prime Minister, Gordon Brown, has announced that he plans to start charging supermarkets for using the bags in an attempt to halt the rate at which they are handed out.
It had been claimed the huge number of plastic bags thrown away throughout the world had led to huge numbers of seabirds, turtles, seals and fish being killed. In the UK alone, 13 billion were given to shoppers last year.
But several experts are now saying there is not any direct evidence to back up these figures and the Government has been accused of "jumping on a bandwagon based on poor science".
Dr David Laist wrote a study as far back as 1997 on the impact of plastic bags on the environment and yesterday he said his findings were totally at odds with claims that they kill animals when discarded.
He added: "Plastic bags do not figure in entanglement. The main culprits are fishing gear, ropes, lines and strapping bands. Most mammals are too big to get caught up in a plastic bag. The impact of bags on whales, dolphins, porpoises and seals ranges from nil for most species to very minor for perhaps a few species. For birds, plastic bags are not a problem either."
Lord Taverne, chairman of Sense about Science, a charitable trust, said "The Government is irresponsible to jump on a bandwagon that has no basis 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 does not achieve anything."
Those who support the clampdown on plastic bags claim up to 100,000 mammals and one million seabirds are killed every year by them.
However, this is based on research published in Canada in 1987, the findings of which, critics claim, have been misinterpreted.
The study, carried out between 1981 and 1984 found that during that period, 100,000 marine animals were killed by discarded nets. It did not, however, mention plastic bags.
Fifteen years later, the Australian government conducted a report into the impact of discarded plastic bags and its authors, using the previous Canadian inquiry, mistakenly attributed the deaths to plastic bags instead of "plastic litter".
Dr David Santillo, a marine biologist for Greenpeace, said: "It is very unlikely that many animals are killed by plastic bags. The evidence shows just the opposite. We are not going to solve the problem of waste by focusing on plastic bags. It does not do the Government's case any favours if you have got statements being made that are not supported by the scientific literature which is out there."
His comments were backed up by Professor Geoff Boxshall at the National History Museum, who said: "I have never seen a bird killed by a plastic bag.
"Other forms of plastic in the ocean are much more damaging. Only a very small proportion is caused by bags."
Following the PM's pledge in the House of Commons, several prominent high street retailers including Marks & Spencer and Ikea vowed to cut down on the number of plastic bags that they issued.
And Brown promised that if stores did not take it upon themselves to act, then he would not hesitate to do so himself.
He warned: "If government compulsion is needed to make the change, we will take the necessary steps.
"We do not take such steps lightly – but the damage that single-use plastic bags inflict on the environment is such that strong action must be taken."
It is not the first time that claims about the damage caused by plastic bags have been criticised.
In 2006, the Australian Productivity Commission conducted an examination of the risks and came to the conclusion that just 2% of the country's litter comprised plastic bags. They could not be certain if there was any definite risk to wildlife.
In fact, they stated that plastic bags may actually be good for the environment and eco-friendly in solid landfill, because of their "stabilising qualities, leachate minimisation and minimising (of] greenhouse-gas emissions".
But in some countries, moves to ban the use of plastic bags have already started and the US is leading the way.
In January, New York City announced a bill to force large stores to set up recycling schemes to tackle the estimated one billion plastic bags handed out to shoppers each year.
An easy environmental targetThe anti-plastic bag campaign is the current favourite environmental campaign.
Following the devastating floods in Bangladesh in 1998, the government in the capital, Dhaka, announced it was banning plastic bags, blaming them for blocking the nation's drainage network.
Ten years on and the subject has returned to the UK public forum with the Prime Minister, Gordon Brown, stating last month: "
The damage that single-use plastic bags inflict on the environment is such that strong action must be taken."
His call has been backed by the Daily Mail which is currently running a campaign to ban the bags. It has been claimed that the bags take up to 1,000 years to break down and that many marine animals, among them seals, porpoises and turtles, die each year as a result of eating them.
But critics say decomposition generally takes around 20 years and that it is pieces of solid plastic which are much more of a danger to wildlife, with scientists finding large pieces of carton floating up to 500 miles off the coast. They add that plastic bags have become such an issue simply because they are more visible to the public.
The full article contains 1002 words and appears in Scotland On Sunday newspaper.
