A very topical issue at the moment is single-use plastic bags referred to in the industry as lightweight HDPE bags. We have all seen the horror pictures of autopsied sea creatures and the plastic contents of their digestive systems. This is moving stuff and there has been a groundswell of public opinion urging companies to stop using single-use bags. This has been reasonably successful with several NZ supermarkets committing to phasing out single-use bags in their stores. The public, in general, has applauded this shift and we have proudly purchased our sets of reusable shopping bags knowing that in some small way we are doing our bit. But do we really understand the relative benefits of moving to paper, low-density polyethylene (LDPE - common supermarket reusable), non-woven polypropylene (PP - heavy duty stiffened bags) or cotton based reusable bags?

Here’s some information for you to consider and apply to your actions when it comes to
reusable bags.

  • Regardless of the type of bag you use the key to reducing its impact is to use it as many times as possible.
  • The reuse of single-use HDPE bags as bin liners immediately reduces its footprint and when they are replacing traditional heavy-duty bin liners the benefits are even greater.
  • Reinforced paper, starch-polyester or cotton-thread based reusable bags have significantly greater footprints due to resource-intensive production and increased transport energy requirements (as they are heavier).
  • In order for reusable bags to have a similar carbon footprint as single-use HDPE bags (that have been used as a bin liner) they need to achieve the following;
    • Paper bags used 7 times
    • LDPE reusable bags used 9 times
    • PP heavy-duty reusable bags used 26 times
    • Cotton bags used 327 times

It is clear that moving away from single-use bags is the right thing to do. However, we need to be informed and smart about what we replace them with. If you do have single-use bags do what you can to make them multiple use. If you haven’t already make sure their final use is as a bin liner. Challenge yourself to get the maximum number of uses out of that bag as possible. When choosing reusable bags be clear that you will need to use that cotton bag 327 times before there is any positive outcome compared to single-use HDPE bags, so choose one you really like.

What we need to talk about is our consumer habits. What can we do in our day-to-day lives to limit our reliance on quick fixes often justified as convenience? When we do reach for convenience we can soften the impact by challenging ourselves to maximise use and reduce the footprint of those choices.

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1 comment(s)

  • Tristan Vine

    Single Use Plastic bags for us get used twice, once to carry the shopping, twice as rubbish bags - which contain household rubbish - and into the curb-side bin. We don't buy additional plastic bin liners. As much as we do to mitigate the amount of single use plastic we obtain, I think to instantly reduce this to zero - for anyone - is pretty hard. Awareness and small steps are key. There are several factors for my wife and I have to consider, even just for groceries: We are irregular shoppers - both working intense, full-time jobs, living another town away. Having last minute social lives, sporadic meetings and things on in the evening means we cannot pre-prepare a big shop-up, resulting in one of us quickly grabbing food on the fly for that night's meal. This means we don't always have re-usable bags with us. We also shop at the most easy accessible supermarket - which is not Pack-n-Save who have boxes I'd gladly use. While I'm glad supermarkets are removing plastic bags, they need to supply old boxes, not bags you have to buy. Those fabric bags are another cost; (to the consumer and the company - and probably increase the carbon footprint through extra supply-chain, manufacture and delivery...). For us they will pile up at home and probably get thrown out. Better sustainable practice for these supermarkets would be to supply the boxes for shoppers to pack in, minimizing their own waste in the process as well. The cardboard for us gets used in the fire - which is sustainable for us too. Pack-n-Save had it right from day one, before they introduced their OWN yellow bags.