Reusing is the best option
The discussion on the use of plastic bags, which are no longer available for free in some supermarket chains around the country, has gained strength in the last few months. Part of the retail chains already encourages consumers to use the returnable model – considered to be less aggressive to the environment. Another part continues to hand out plastic bags, which, in some residences, are reused for waste disposal. The question is: are the disposable models indeed nature’s villains?
The best answer to this question is: not always. This is what is revealed by an unprecedented study in Brazil developed by Espaço ECO Foundation in partnership with Akatu Institute, and Braskem, the greatest producer of thermoplastic resins in the Americas. The comparative study has assessed different types of bags available in the Brazilian market, among them are the disposable ones (made of traditional polyethylene, sugar cane polyethylene, and the ones supplemented with oxo-biodegradation promoter), and some returnable ones (paper, raffia, fabric, and non-woven fabric).
The study demystifies the fame of villain carried by the traditional polyethylene bags – the most common type in supermarkets in Brazil. From a scientific analysis, which took into consideration the economical and environmental impacts of each alternative, what was concluded is that it all depends on the consumer’s attitude. “The best bag is determined by the context in which it is used, which can vary according to the volume of items purchased, the number of trips to the supermarket, and the frequency of waste disposal”, explains Beatriz Luz, coordinator of the study at Braskem.
From birth to death
The study was based in Life-cycle Assessment (LCA), a methodology which measures environmental impact of products since their “birth” to their “death.” Aspects such as raw material extraction, productive processes, consume and disposal of the bags were assessed. “LCA gives us a more realistic result of the environmental impact, and it is a crucial working tool for those companies which are concerned about uniting development and sustainability”, highlights Beatriz.
The study shows, among other things, that the degradation time of the bags is not a criterion to be taken into consideration before choosing the best option when taking purchases home. This is because the material’s decomposition is less important than its life cycle in nature, which can be extended by recycling and by domestic habits, such as reusing the same package several times.
Beatriz explains that a LCA study on bags had already been conducted by the UK Environment Agency, focusing in the United Kingdom. Therefore, the idea was to replicate it in the Brazilian reality. In a year, several situations were assessed: larger or smaller volume of items purchased, higher or lower frequency of trips to the supermarket, larger or smaller disposal of waste, type of raw material used in the production of bags, load capacity, cost of each bag and its reutilization, in addition to possible recycling.
The combinations of each of these scenarios, crossed between them in a graph which established different weights according to the generated impact, lead to interesting conclusions. One of them is that the disposable polyethylene bags – the most common, available at supermarkets’ checkout – present a better eco-efficiency in situations in which consumers have a smaller volume of purchases, go less frequently to the supermarket (up to twice a week), and dispose of a lot of waste, reusing the same bags.
“On the other hand, returnable bags made of fabric or plastic have a better eco-efficiency when the consumer shops greater volumes, goes very frequently to the supermarket (more than three times a week) and disposes little waste”, says Sônia Chapman, Director-President of Espaço ECO Foundation, during the launch of the study. An important detail: the study did not find scenarios in which the paper bag presented advantages over the other alternatives. This happens because, when compared to other packaging, it requires a greater amount of raw material to be produced.
The study shows, additionally, that the main challenge is to reach the maximum point of durability with less raw material. It also reveals that there were no significant elements which could prove an ecological advantage of the oxo-degradable bag (the degradation process of which is faster, of approximately 18 months after its disposal) compared to the other disposable options. This is due to its decomposition process, which depends on specific climate conditions, besides liberating polluting gases and heavy metals.
“Every bag has an impact. So, the consumer must always use the maximum load capacity of the bag, and must reuse always, when possible. This way, the environmental impact of the chosen option will be reduced”, emphasizes Beatriz.
When going to the supermarket, it is worth giving this some thought. And then some more. Because the best choice does not depend only on the technology used for the manufacturing of the indispensable shopping packages. The best choice lies in the consumer’s good judgment.