I have just had the results in from a beach litter survey run by the Marine Conservation Society once a year here in the UK. I helped to organise an event at my local beach, and with some volunteers collected and recorded all the washed up and discarded litter that we found. 374 beaches took part in the UK, and the information collected will be used to lobby governments and to encourage the public to take a more responsible approach to litter.
The results show that, nationwide, 59% of all the rubbish collected was plastic - and from my own survey, I know that a lot of this was plastic bags. The amount of plastic rubbish had also increased by 146% since 1994. Plastics take years and years to break down, and pose a serious threat to marine life which can become tangled up in or choked by ingesting plastic rubbish (amongst other things).
My point is, please think twice before accepting those plastic carrier bags at the supermarket, take your own reusable bags and reduce the number of these unsustainable products that are littering up our planet.