Plastic bags do not bio-degrade so should not be used for poo collection. Surely dog owners who leave poo spread across the pavement are helping the environment.

Of course while people are complaining that eating meat is evil in a world where the land could be used for growing crops to feed hungry people, there cannot be anything worse than growing crops to feed to animals which are in turn feed to other animals which serve no practical purpose. At least with bio-fuels they get you from A to B, but a dog in a city is just a waste of resources. In the words of another thread - it's a disgrace to health and the environment.