Why Worry – Reusable Carrier Bags
Elle Mileti
Sustainability Problems – STSS 4270
Fall 2012, Costelloe-Kuehn
11 September 2012
The traditional, thin plastic bag, though increasingly demonized and taxed, has better environmental
performance and is likely to be considerably safer for human health than alternatives. – Kenneth Green
It should be first understood that the debate between reusable carrier bags versus the traditional plastic
bags is not a debate between environmentalism and capitalism. In fact, there is never a debate between
environmentalism and capitalism as the two are concepts that can no more be compared than driving a
car can be paralleled to the emotion of love. They can, however, overlap; much like how one can love
her car, one can make capitalistic profit while promoting and progressing the sustainability movement.
This paper is intended to bring to light a detrimental cultural phenomenon that brings more harm than
good to the environmental movement: a lack of understanding when it comes to human products.
When it comes to sustainability, scientific data should not be overlooked for argument’s sake. The
objective should be progress and regardless of whether or not that means reevaluating current policy or
returning to prior policies and practices, such action should be taken and not substituted by feel-good
means. Eliminating factors results in equations that don’t parallel actual circumstances and mean
nothing when it comes down to it. Additionally, new doesn’t always mean better, and more importantly,
old doesn’t always mean worse. If it becomes practice to try and best understand the entire equation
for sustainability true progress can be made.
This crucial need for understanding is exemplified in the following argument for the continued use of
plastic carrier bags when grocery shopping. The goal isn’t to halt innovation; it is to optimize it by
efficiently directing focus towards actual solutions and realizing when attempted corrective action is
actually more harmful.
There are two substantial arguments for the continued use of traditional plastic shopping bags over the
trending reusable ones: the spread of disease and carbon footprint. Recent studies1 have brought to
light the disgusting truth that reusable shopping bags are breeding grounds for dangerous microbes.
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Why Worry – Reusable Carrier Bags
When shoppers put things into their bags, they can contaminate the bag which then in turn can
contaminate previously uncontaminated food. Furthermore, even individually packaged food can easily
become contaminated2 through human contact with first the bag and then the food. Direct contact
between sick persons is not necessary for the spread of disease and common human practice easily adds
to the risk3. For example, few people are found to separate vegetables and raw meat into different bags
and most people store their bags at home or in the car between uses, subjecting them to warmer
temperatures which increase bacterial growth4. Most upsettingly, it was found that only about 3% of
people ever clean their reusable bags5.
In addition to health concerns, a “cradle to grave” life cycle assessment (LCA) compared the
environmental impact of traditional shopping bags to six other types of bag6. LCA identifies the material
and energy usage, emissions and waste flows of a product, process, or service over its entire life cycle to
determine its environmental performance. Taking into account all the significant life cycle stages from
raw material extraction, through manufacture, distribution, use and reuse, to the final management of
the carrier bag as waste, the study actually showcases that since lifecycle impact is dictated by raw
material extraction and bag production7, reusable carrier bags have a much greater global warming
potential than traditional plastic bags8.
Figure: The amount of primary use required to take reusable bags below the global warming potential
of HDPE bags with and without secondary reuse9.
Such study, as of the environmental performance of reusable versus traditional carrier bags, shows that
when evaluating the impact of a product it is critically important to look at all stages of product life
cycle. If stages are eliminated from assessment, time, money, and other resources are wasted on
ineffective or even counter-effective measures to achieving true sustainability.
Materials Abbreviations
HDPE - High density polyethylene
LDPE - Low density polyethylene
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Why Worry – Reusable Carrier Bags
LLDPE - Linear low density polyethylene
PA - Polyamide
PE - Polyethylene
PET - Polyethylene terephthalate
PLA - Polylactic Acid
PP - Polypropylene
PVC - Polyvinyl chloride
Footnotes
1
(Repp, and Keene), (Gerba, Williams, and Sinclair)
2
(Repp, and Keene, page 2)
3
(Gerba, Williams, and Sinclair, pages 5-8)
4
“Bacteria in bags to which meat juices were added did grow within two hours of storage. Within this
time the number of bacteria increased 10-fold when the temperature was 47°C [116.6°F] inside the
trunk…warm temperatures and presence of food in the bags can encourage rapid growth of bacteria.”
(Gerba, Williams, and Sinclair, page 11)
5
(Gerba, Williams, and Sinclair, page 8)
6
Bags studied: A conventional lightweight bag made of high-density polyethylene (HDPE); an HDPE bag
doped with a chemical to speed its degradation; a lightweight bag made from a biodegradable starchpolyester blend; a regular paper bag; a heavy-duty “bag for life” made from low-density polyethylene
(LDPE); a heavier duty polypropylene bag; and a cotton bag (Edwards, and Meyhoff Fry pages 12-13)
7
“The GWP of all of the carrier bags studied is dominated by raw material extraction and production
which ranges from 57 per cent of the impact for the starch polyester bag to 99 per cent for the cotton
bag. This impact is normally due to the production of the most prevalent material with 64 per cent of the
HDPE bag impact generated directly from the extraction and production of HDPE.”; “The environmental
impact of carrier bags is dominated by resource use and production. Transport, secondary packaging and
end-of-life processing generally have a minimal influence on their environmental performance.”
(Edwards, and Meyhoff Fry pages 32-61)
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Why Worry – Reusable Carrier Bags
Figure: Energy consumption and waste generation for film and cotton bags (per 1000 bags) (Edwards,
and Meyhoff Fry page 28)
8
“The conventional HDPE bag had the lowest environmental impacts of the lightweight bags in eight of
the nine impact categories. The bag performed well because it was the lightest bag considered. The
lifecycle impact of the bag was dictated by raw material extraction and bag production, with the use of
Chinese grid electricity significantly affecting the acidification and ecotoxicity of the bag.” ; “The key to
reducing the impact of all carrier bags is to reuse them as much as possible and wehre reuse for
shopping is not practical, secondary reuse in application such as bin liners is beneficial.” ; “Reusing
lightweight carrier bags as bin liners produces greater benefits than recycling bags due to the benefits of
avoiding the production of the bin liners they replace9.” (Edwards, and Meyhoff Fry pages 59-61)
9
“40.3 per cent (53 per cent of 76 per cent) of all lightweight carrier bags avoided the use of bin liners.
The volume and weight of an average HDPE bin liner was calculated to be 29.3 litres and 9.3 grams,
using the same measurement methods applied to the carrier bags in this study. Therefore, for every 19.1
litre lightweight plastic carrier bag that was reused, an avoided burden of 6.1grams of HDPE bin liner
was subtracted from the system.” (WRAP, 2005)
Additional Notes
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Why Worry – Reusable Carrier Bags
The Environment Agency study also did not include the energy requirements of washing cloth bags in
hot soapy water or bleach to sanitize them. (Edwards, and Meyhoff Fry)
“Because the norovirus has been reported to survive on surfaces up to four weeks at room temperature,
disinfection is recommended with commercial products or a solution of ½ cup of bleach to 1 gallon of
water. Norovirus is killed at temperatures above 140 F…” (www.emedicinehealth.com, 2012)
“A full 90 percent of the energy used in washing clothes goes toward heating the water…”; “It turns out
that pressing the cold/cold button (instead of the hot/warm button) on your washing machine has the
same impact as driving about 9 miles in a car or the production, transportation and storage of a six pack
of beer. It may not be too surprising that one load of laundry doesn't make a huge amount of difference
…But, multiply those impacts by 392 -- the number of laundry loads an average U.S. home washes in a
year -- and, all of the sudden, there are some real impacts.” (www.treehugger.com, 2008)
References
Repp, Kimberly, and William Keene. "A Point-Source Norovirus Outbreak Caused by Exposure to
Fomite." Journal of Infectious Diseases Advance Access. (2012) Print.
Gerba, Charles, David Williams, and Ryan Sinclair. "Assessment of the Potential for Cross Contamination
of Food Products by Reusable Shopping Bags." Department of Soil, Water and Environmental Science,
Univeristy of Arizona; School of Public Health, Loma Linda University. (2010) Print.
Edwards, Chris, and Jonna Meyhoff Fry. United Kingdom. Environment Agency. Life Cycle Assessment of
Supermarket Carrier Bags. Horizon House, Deanery Road, Bristol BS1 5AH: Environment Agency, 2011.
Print.
Waste and Resources Action Programme (WRAP), 2005. Carrier Bag Usage and
Attitudes. Benchmark and Target Market Study.
Green, Kenneth. "A Punching Bag No More." American: The Online Magazine of the American Enterprise
Institute. 26 March 2011: n. page. Web. 9 Sep. 2012.
<http://www.american.com/archive/2011/march/a-punching-bag-no-more>.
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Dunn, Collin. "Washing Laundry in Cold Water is the Same As...." TreeHugger.com - Discovery
Communications, LLC . 15 December 2008: n. page. Web. 9 Sep. 2012.
<http://www.treehugger.com/culture/washing-laundry-in-cold-water-is-the-same-as.html>.
Davis, MD, PhD, Charles. "Norovirus." emedicinehealth - WebMD. 02 February 2012: 11. Print.
<http://www.emedicinehealth.com/norovirus/page11_em.htm>.
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