The Scottish Government spent over two years analyzing the plastic bag issue. They held hearings and received testimony from experts and a number of governments from around the world. In 2005, the government issued a full environment impact assessment report, which included a comparison of the environmental impacts of plastic and paper bags. The report states (page 31): “[A] paper bag has a more adverse impact than a plastic bag for most of the environmental issues considered. Areas where paper bags score particularly badly include water consumption, atmospheric acidification (which can have effects on human health, sensitive ecosystems, forest decline and acidification of lakes) and eutrophication* of water bodies (which can lead to growth of algae and depletion of oxygen).

Paper bags are anywhere between six to ten times heavier than lightweight plastic carrier bags and, as such, require more transport and its associated costs. They would also take up more room in a landfill if they were not recycled.” A table comparing the environmental life cycle impacts of paper versus plastic is on page 23 of the report. The plastic bag was given a score of 1 in all categories as a reference point. A score greater than 1 indicates greater contribution to environmental problems than plastic, when normalized against the volume of goods transported in the bag. In all categories, with the exception of litter, the plastic bag has a smaller environmental footprint.

Indicator of Environmental Impact Plastic bag

HDPE lightweight*

Paper bag Consumption of nonrenewable primary energy 1.0 1.1 Consumption of water 1.0 4.0 Climate change (emission of greenhouse gases) 1.0 3.3 Acid rain (atmospheric acidification) 1.0 1.9 Air quality (ground level ozone formation) 1.0 1.3 Eutrophication of water bodies * 1.0 14.0 Solid waste production 1.0 2.7 Risk of litter 1.0 0.2 *HDPE lightweight refers to a conventional plastic grocery bag (High Density Polyethylene) U.K. Government Environment Agency Study Report, 2011

"A Life Cycle Assessment of Supermarket Carrier Bags" http://publications.environment-agency.gov.uk/PDF/SCHO0711BUAN-E-E.pdf The U.K. Environment Agency did a life cycle assessment comparing the environmental impacts of conventional plastic grocery bags (High Density Polyethylene- HDPE) with a number of other supermarket carry bags including paper, longer-life bags (cotton, non-woven polypropylene), plastic bags-for-life (low density polyethylene), and a starch polyester blend bag. The study found that: The conventional plastic shopping bag (HDPE) outperformed all alternatives, even reusables, on environmental performance.





Conventional plastic bags have a much lower global warming potential. The environmental impact of all types of carry bags is dominated by the resource use and production stages. Transport, secondary packaging and end-of-life management generally have minimal influence on their performance. Heavier, sturdier bags of all materials have a higher global warming potential. For example, the production of cotton with its heavy pesticide and water use has a negative impact on the environmental benefit of cotton bags. Whatever type of bag is used, the key to reducing the impacts is to reuse it as many times as possible. The reuse of conventional HDPE and other lightweight carrier bags for shopping and/or as bin-liners is pivotal to their environmental performance, and reuse of bags as kitchen catchers produces greater benefits than recycling bags. The study identified that 40.3% of plastic bags were reused as bin liners in the UK. Conclusions: Paper bags would have to be used three times to lower their global warming potential to match that of a conventional HDPE plastic shopping bag being used just once.





LDPE bags (thicker polyethylene bags for life) would have to be used four times; non-woven polypropylene bags 11 times; and cotton bags 131 times. Starch-polyester blend bags have a higher global warming potential and abiotic depletion than conventional polymer bags, due both to the increased weight of material in the bag and its higher material production impacts. The number of times each bag would have to be reused to match the environmental performance of conventional (HDPE) plastic carrier bags is shown in the table below (with and without secondary reuse of the conventional plastic bag).





For example, a cotton reusable bag has to be reused 131 times to be as good environmentally as a plastic shopping bag used just one. Amount of Primary Use of Alternatives to Match the HDPE Conventional Bag Environmental Performance With or Without Secondary Reuse of the HDPE Bag Type of Carrier Bag HDPE Bag

(No Secondary Reuse) HDPE Bag

(40.3% reused as kitchen catchers) HDPE Bag

(100% reused as kitchen catchers) HDPE Bag

(reused 3 times) Plastic Bag 1 2 2 3 Paper Bag 3 4 7 9 LDPE Bag 4 5 9 12 Non-woven PP Bag 11 14 26 33 Cotton Bag 131 173 327 393 Eco-Bilan Carrefours Life Cycle Analysis, 2004 Evaluation des impacts environnementaux des sacs de caisse Carrefour

Eco-Bilan (a division of PriceWaterhouseCoopers) is noted worldwide for its expertise in life cycle analysis. In 2004, Eco Bilan carried out a life cycle analysis on paper and plastic bags for Carrefour, a very large French retailer. The results were definitive – plastic is environmentally superior to paper. The full report is accessible at the bottom of this web page. A snapshot of the findings comparing plastics to paper follows: