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
PACKAGING TECHNOLOGY AND SCIENCE
Packag. Technol. Sci. 2010; 23: 145–160
Published online 29 January 2010 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/pts.886