Plastic bags. It's hard to believe, but 40 years ago they were something of a novelty. In recent years, however, shops and supermarkets have got into the habit of handing them out at the drop of a hat for even the smallest of purchases. The result: they have become a major pollutant and a threat to wildlife.

The World Wide Fund for Nature estimates that more than 100,000 whales, seals and turtles die every year from either ingesting plastic bags or being ensnared by them. In India, about 20 cows die every day because of "eating" plastic bags. And in China, the local and global effect of discarded plastic bags is known as "white pollution".

The Pacific Ocean is home to a vast floating mass - the size of France - of discarded plastic packaging, including bags, which weigh 3 million tons. But now, from China to the United Kingdom, countries are slowly taking action to rid the world of the plague of plastic bags, many of which take years to decompose, if at all.