Some "green" polypropylene bags are not made to last and end up in landfill just as a plastic bag would. Most of these bags made from polypropylene fibres come from China where hundreds of manufacturers compete with each other to sell them to the rest of the world. As the quality of the bags varies nfrom those that can last years to those that rip easily after a few shopping trips.
“There are very poor quality bags because there is no standard for these bags in Australia and the industry is very competitive. Competitors undercut on price and deliver poor-quality bags. There are retailers who buy from the cheaper manufacturers just for a higher profit margin,” says a spokesman from Non Woven Bags Direct Australia, a South Australian company which manufactures these bags in China.
The bigger problem is that buying and using poorer quality bags cancels out your efforts to be sustainable. RMIT’s Centre of Design conducted research on the lifecycles and the environmental impact of plastic, paper and cloth bags between 2002 and 2003 (commissioned by the federal Department of Environment and Heritage) and found that one green bag (loaded with about 70 items a week), if used for two years, would offset the use of 114 plastic (polyethylene) bags. They also found that the production of one polypropylene bag produces 373g of greenhouse gases compared with 16g for one plastic bag.
“How environmentally friendly a polypropylene bag is depends on its lifecycle, or how many times it is reused,” says Dr Katherine Dean, research scientist at CSIRO Materials Science and Engineering. “When buried in landfill, polypropylene, like polyethylene, takes hundreds of years to break down.”
It appears that consumers are trying to do the right thing, looking at the strong consumer demand for these bags. Woolworths sold 5.7 million green bags in the 2008 financial year compared with 3.4 million in 2007. Sales are expected to spike as the legislative and voluntary ban of plastic bags around the country kicks in. South Australia became the first state to ban retailers from providing lightweight plastic checkout bags. Target also followed suit, charging a levy for plastic bags in their stores nation-wide.
The claim that these polypropylene bags are good for the environment, then, is based on the assumption that they last long enough and can be used many times to reduce your use of plastic bags. A Woolworths spokesman told CHOICE that it supports this by ensuring that all its polypropylene bags - which are sourced from a number of different manufacturers in China - weigh 90gsm. “This gives us the correct strength to enable long-term use for our customers' everyday shopping needs,” he said.
Manufacturers told CHOICE that a bag should be made from polypropylene that weighs between 80gsm and 100gsm for it to be able to last between four and five years of use. Generally, the thicker the bag and the better the stitching, the longer it will last.
Buying a durable green bag
- the thicker the material, the better.
- Seams should be firmly sewn, with no loose threads.
- A piping, or small plastic board at the bottom of the bag acts as a weight distributor and will help the bag last longer.