and the answer is not what it seems…
Which shopping bags are most sustainable: reusable, plastic, cotton or paper bags?
Shopping bags come in all shapes, color, sizes, material… and we love them all.
I personally feel bad when I end up accepting a plastic bag where I actually do not need it. Most of the time, but not always, I refuse. When things come in a paper bag, and better even in a bag of recycled paper, I have no trouble with my eco-consciousness. But the question is, should I ? Is the answer so obvious as it seems?
You guessed right, it’s not. Cause we shouldn’t be comparing apples to oranges. Here is a list of three criteria to make you better understand the difference of impact different types of bags can have. At the end, by adding up the cost of each criteria we can calculate the total environmental impact.
I have been living in Buenos Aires for over three years now. People here finally start recycling. But it will take more than one generation to create a general awareness of the need to reuse, use less and recycle.
Below you will find a technical chart of a reusable shopping bag made in China. First , the chart does not give a clear indication, ‘material: non-woven‘, then next ‘non woven, Rpet, cotton’ of what material the bag is made from. Yet it is marketed as a 100% eco-friendly bag! This is just an example of how repeatedly misleading the product is sold. Depending on the quantity, the product sells for as low as 0,35 USD. 40% of its production is shipped to the U.S., 20% goes to Western Europe with only 11% destined for the local, Chinese, market.
In order to ‘calculate’ the environmental impact of a bag, the following 3 criteria have to be looked at:
WHAT GOES INTO THE PRODUCTION OF EACH BAG:
- Natural resources
What is the bag’s life spam ?
What happens after we dispose of the bag ?
PAPER vs. PLASTIC vs. REUSABLE
Manufacturing a PAPER bag requires about four times as much water as a plastic bag. Additionally, unless they are made from recycled material, the fertilizers and other chemicals used in tree farming and paper manufacturing contribute to acid rain and eutrophication of waterways at higher rates.
The standard grocery store PLASTIC bag is made from high-density polyethylene (HDPE). Studies agree that plastic bags are by far the least costly (i.e., carry the smallest ecological footprint) to produce. Still, there is no way around the fact that plastic is derived from petroleum. Petroleum is a finite resource, and as it becomes increasingly limited, obtaining it becomes increasingly damaging to the environment.
REUSABLE bags may be made from many different materials. The two most common types are cloth bags and nonwoven polypropylene (PP), a more durable type of plastic; Cloth bags are typically made from cotton, a particularly pesticide-intensive and water-guzzling crop. Only in few cases are they made from hemp fiber.
Reusable bags made from nonwoven polypropylene plastic are also common, and they’re actually less carbon-intensive to produce.
One additional factor which cannot be ignored is when these bags are shipped to their destination. Transportation cost and its impact on the environment are important elements too to be taken into account.
HOW LONG IS THE LIFESPAM
The environmental impact of the production is only one factor to be considered. It speaks for itself that the impact will be lower the more we use and re-use a bag.
Whereas reusable bags require more material and more energy input than disposable bags, the fact that they can be re-used reduces their impact considerably.
If we take the basic plastic bag ( made of HDPE- High Density Polyethylene ) the lightweight single-use plastic bag you find at almost every grocery store, as a standard ( for being the one with the least impact during production ), one will need to reuse
- the paper bag 4 times
- the polypropylene bag 14 times
- the cotton bag 173 times
for each bag having the same impact based on production and lifespam.
Once we have used the bag until we can or will no more, how can we dispose of the bag, its components, the materials it is made of? What impact do the materials have?
Paper bags are biodegradable and easy to recycle or compost.`
The problem with plastic bags is that they can be recycled but usually aren’t. They end up gathering in the streets, the ocean and landfills, where they endanger wildlife and never biodegrade.
Since cotton is made by nature, it can be biodegraded by nature. And biodegrading cotton to the original building blocks that nature used to create it makes these building blocks available to create new living things.
Products made with cotton are biodegradable and compostable. While the speed that cotton degrades depends on the environmental conditions (amount of oxygen, water, temperature, pH, etc.) and construction of the fabric (weight, how tightly the fibers are packed together, etc.), at least we know it will degrade over time, and not remain in the waste stream.
Yet, a study states that the global warming potential of cotton bags is more than 10 times the impact of any other bag.
Knowing this ‘breakeven’ number is important because it will help you to truly reduce your environmental impact.
In the end, your actions will make the greatest difference — not the bag itself. The most sustainable choice is one that’s sustainable for you. What are your preferences? Which considerations, environmental or otherwise, are most important to you? And which lifestyle changes will you make for the long-term?
In my next post I want to show you two case studies in Argentina. The first case, MODESTA, shows how you can, – by taking one little effort in collecting your daily plastic bags, – soon be the proud owner of a 100% recycled plastic handbag.
The second case study is another Buenos Aires based company, MACETELA. This fairly young company turns plastic bottles into garden pots and shopping bags.
Watch out for my next post !