What are the main conclusions of the UK Environmental Agency’s life cycle assessment of supermarket carrier bags?
- Amongst the different types of carrier bags studied (including HDPE, LDPE, biopolymer (starch-polyester), non-woven PP, paper & cotton bags), HDPE bags have the lowest overall environmental impact
- For all types of carrier bags, the key determinant of their environmental impact was the degree to which they were re-used
- Paper, non-woven PP and cotton bags have to be re-used 4, 14 and 173 times respectively for their global warming potential to be less than that of HDPE bags (assuming 40% of HDPE bags are re-used as bin liners)
- Bio-polymer (starch-polyester) bags have greater global warming potential than conventional plastic bags due to “the increased weight of material [per] bag, higher material production impacts and a higher end-of-life impact in landfill”