The secret message of plastic bags


I got interested in plastic bags and their environmental impacts compared to other alternatives to packaging and carrying your groceries every day from the list of things to think about given in the lecture slides.

As a result of concerns of the environmental impacts of plastic bags, a number of countries and cities have already introduced regulations to reduce consumption of the bags or to eliminate them completely. Some retailers here in Finland have also taken action to reduce bag consumption in the absence of regulation; for example Hok-Elanto has stopped completely selling regular plastic bags, at least in S-markets, and only sells recycled ones.


Some interesting facts I found:

(Evaluating the sustainability impacts of packaging: the plastic carry bag dilemma)


• Plastic carry bags require 20–40% less energy than paper carry bags at a zero recycling rate for both bags. As recycling rates increase the energy difference decreases because of the higher energy saving from recycling paper compared to plastic. The energy requirements become equivalent at a 60% recycling rate.

• Plastic bags contribute 70–80% less solid waste than paper bags and this difference remains stable at all recycling rates.

• Atmospheric emissions for the plastic bag were 63–73% lower than the paper bag and these differences continue regardless of the recycling rate.

• At a zero recycling rate the plastic bag contributed over 90% less waterborne emissions than the paper bag. This difference increased at higher levels of recycling because of the process involved in recycling paper.

In this article they used the LCA (life cycle analysis) and further found out that reusable carry bags have the lowest impact across all of the measured impact categories, assuming that the bags are reused at a high rate (according to this LCA, at least 50 times).  They also suggest that a policy of promoting reusable bags to customers and discouraging use of plastic bags is better from an environmental perspective because they are more efficient in their use of materials, energy and water, safer for the environment and more cyclic if reused many times. The single-use paper bag was found to have the highest impact, or equal highest impact, for all categories included in their LCA. One of the implications and further suggestions in this article was that consumers should be encouraged to buy reusable bags, and then to keep using their existing bags rather than continuously buying new ones. They concluded also that reusable bags should never be given away free because this would only encourage over-consumption.

The LCA results here suggested that replacing one single-use bag (plastic) with another (e.g. paper or a biodegradable plastic) may increase (!) rather than decrease environmental impacts.

Finally the study concluded by saying that the best overall environmental outcome requires retailers and regulators working in partnership and providing a shared and consistent message to consumers. Quite obvious the partnership part I say, but what is the shared message to consumers? Has it do with the different bags at all, or has it more to do with over consumption?


Evaluating the sustainability impacts of packaging: the plastic carry bag dilemma

By Helen Lewis, Karli Verghese and Leanne Fitzpatrick


Packag. Technol. Sci. 2010; 23: 145–160

Published online 29 January 2010 in Wiley InterScience ( DOI: 10.1002/pts.886

1 comment
  1. Elina said:

    I decided to continue writing about the shopping bags as it seems to be a topical issue. Finland’s environmental administration made a research in 2004 about the environmental impacts of paper, plastic, and biodegradable bag. The following writing is based on this research.

    The environmental impacts of a shopping bags are not significant when they are compared to people’s overall consumption. From the annual amount of household waste, shopping bags cover around 0,2 – 0,3 %. Compared to one person’s daily consumption, shopping bags have a minor impact. For example, the impact of 100 shopping bags are approximately 1/5 of one person’s daily greenhouse emissions. In other words, all the shopping bags that one person consumes during 5 years causes as much emissions as one person causes with his/her daily activities in one day. However, regardless of the minimal overall impact, shopping bags have a high symbolic value as an artifact of disposable culture.

    In many countries, plastic bags are banned or their use is controlled by taxes. The grounds for these actions have been based either on minimizing littering, reducing dependence on oil, or controlling climate change. During the years, various life cycle analyses have been made of shopping bags, but none of these research studies can be applied directly to Finland, because of the differences between Finland and other countries, such as consumer habits, waste management, and energy production. For example, the LCA of a paper bag is different in Finland than in Central Europe, because Finnish paper industry uses less fossil fuels. In addition, shopping bags’ environmental impact is also dependent on the amount how much they are used per person. In Finland, the average amount of shopping bags is 50/person/year, when in turn in Hong Kong, one person consumes 1460 bags per year.

    The conclusion of the various international LCA research have been, that the emissions of the plastic bags are smaller than the emissions of a paper bag, and according to many studies, the emissions of biodegradable bags are smaller compared to the traditional HD-PE plastic bags. According to the Finnish research, the plastic and paper bags have pretty much an equal impact in Finland when they are examined by their overall carbon dioxide emissions. The best solution according to the study, would be the plastic bags that are manufactured of recycled plastic. The biodegradable bags, on the other hand, are the worst option in Finland compared the paper and plastic bags. However, although these results are directional, the real impacts depend always on how many times the bag is used, and the weight of each shopping bag (e.g. in Finland the most used plastic bags weight 22 g, when in Australia the regular plastic bags weight only 4-6 g). Because of this, we should be careful if we are making any generalizations, because what is good option in one country, might actually be a bad one in another place.

    More information can be found from the following link (in Finnish):

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