[Ed Hammond]

Seems to recall a couple of reviews I've read cover plastic bags as part of wider pieces of work on sustainability and/or climate change.

Not aware of any reviews that just look at plastic bags though!

You might want to try doing some research around the Transition Towns movement. A number of Transition Towns have taken the step of developing voluntary agreements of local shopkeepers to limit the number of bags given out and/or charge for their use. Totnes is a good place to start - they were the first of the TTs and may well have something in place about this.