A report released by the Environment Agency in February 2011 found that ordinary shopping bags are actually greener than supposedly low impact choices. Plastic bags have a much better carbon footprint than cotton holdalls and paper bags. Paper and cotton bags should be reused at least 3 and 131 times respectively to ensure they have a lower carbon footprint. The plastic bag also has a better carbon footprint than “bio-degradable” or “oxo-degradable” bags.
Clearly if the plastic bags are later recovered for mechanical recycling then the footprint improves even further.