Plastic Bags

Myths: Fact or Fiction

Degrade in Landfill Myth

The Single Use Myth

Recycling

Paper vs. Plastic Bags


Paper vs. Plastic Studies

Reusables Greener?

Types of Bags

Litter: The Facts
Public Health

Canada Update

Bags Around the World

The Oil Myth

Made in Canada
Ireland's Bag Tax

Paper vs. Plastic Bags - The Studies


Fiction:
 Many believe that paper bags are more environmentally friendly than plastic bags because they are made from a renewable resource, can biodegrade, and are recyclable.

Fact:  Scientific research - Life Cycle Assessments - show that the opposite is true. Plastic shopping bags outperform paper bags environmentally – on manufacturing, on reuse, and on solid waste volume and generation.

The Facts
  • Multiple studies from Europe and North America show that conventional plastic bags are better for the environment than paper bags.
  • The science shows that plastic shopping bags have a much lower carbon footprint and global warming potential than paper and reusables, if the reusables are not re-used multiple times.

  • This section provides highlights from some of the most recent and credible studies comparing the environmental impact of paper bags versus plastic. They include: the 2005 Scottish Report, the 2011 UK Environment Agency, the Eco-Bilan Carrerfours Paris Life Cycle Study, the USL Report on a number of Life Cycle Analyses, and the North American Boustead Report.
  • The issue of perceived bias is a concern for some, particularly with studies that have received industry funding. Studies with industry funding are identified on this website.  
  • It should be noted, however, that a number of the most important Life Cycle Analyses (LCA's) have been conducted by governments; most notably the governments of Scotland and the UK.

The Science

The Scottish Report (2005) http://www.scotland.gov.uk/Resource/Doc/57346/0016899.pdf

  • 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:

http://www.allaboutbags.ca/Images/papervplasticstudies_clip_image002.gif

ULS Report, 2007
    "Revised Analysis of Life Cycle Assessment (LCA) Relating to Grocery Bags"

The ULS report concludes as follows:

“Legislation designed to reduce environmental impacts and litter by outlawing grocery bags, based on the material from which they are produced, will not deliver the intended results. While some litter reduction might take place, it would be outweighed by the disadvantages that would subsequently occur (increased solid waste and greenhouse gas emissions). Ironically, reducing the use of traditional plastic bags would not even reduce the reliance on fossil fuels, as paper and biodegradable plastic bags consume at least as much non-renewable energy during their full lifecycle”. 


The North American Boustead Report, 2007

http://savetheplasticbag.com/UploadedFiles/2007%20Boustead%20report.pdf

  • The 2007 Boustead report is a life cycle assessment of the environmental impacts of plastic and paper carryout bags in the United States. The Boustead report was commissioned by Progressive Bag Affiliates, a plastic bag industry organization. It was peer reviewed by an independent third party, a Professor of Chemical Engineering at North Carolina State University, an expert on life cycle analysis, and amended accordingly.  

  • The paper bags analyzed in this life cycle assessment had 30% post-consumer content. The recycling scenarios in the Boustead report were 5.2% for plastic bags and 21% for paper bags.

  • The report took into account that a paper bag holds more than a plastic bag and applied an adjustment factor.

  • The Boustead LCA found that:

    • On consumption of non-renewable energy, paper bags used 3.4 times more than plastic bags.
    • On consumption of water, paper consumed 17.3 times more than plastic
    • On emissions of greenhouse gases, paper emitted two times more than plastic.
    • On municipal solid waste generation, paper bags generated 4.8 times more solid waste than plastic bags.

ENVIRONMENTAL IMPACT BASED ON EQUALIZED
CARRYING CAPACITY OF 1,000 PAPER BAGS 

Plastic bags

Paper bags with 30% recycled content 

 Total energy use in megajoules

 763

 2622

 Fossil fuel use in kilograms

14.9

 23.2

 Municipal solid waste in kilograms

7.0

33.9

 Greenhouse gas emissions in CO2 in equiv. tonnes

0.04

0.08

 Fresh water usage in gallons

58

1004

Studies

  1. 2011 U.K. Government Environment Agency Study
    http://publications.environment-agency.gov.uk/PDF/SCHO0711BUAN-E-E.pdf

  2. Scottish Government Report, 2005
    http://www.scotland.gov.uk/Resource/Doc/57346/0016899.pdf

  3. ULS March, 2008 
    Revised Analysis of Life Cycle Assessment (LCA) Relating to Grocery Bags

  4. ULS June, 2007
    Analysis of Life Cycle Assessment (LCA) Data Relating to Grocery Bags

  5. Boustead Associates, North America
    http://savetheplasticbag.com/UploadedFiles/2007%20Boustead%20report.pdf

  6. Ecobilan–Carrefours Study ecol bilan (Évaluation des impacts environnementaux des sacs de caisse, February 2004, #300940BE8):
    French: Ecobilan–Carrefours Study ecol bilan Évaluation des impacts environnementaux des sacs de caisse Carrefour à base d’amidon de maïs. L’ACV a été réalisée par Ecobilan à partir des données recueillies auprès des fournisseurs de sacs. http://www.ademe.fr/sites/default/files/assets/documents/28300_acv_sacs_carrefour_2004.pdf

    English: Ecobilan-Carrefours Study

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