Plastic bags aren’t that bad for environment, study finds

A typical grocery bag is a lightweight carrier made of high-density polyethylene (HDPE). Depending on whether the bag is reused, it may have a lesser environmental impact than others. The study also looked at low-density polyethylene (LDPE), often called 'bags for life', more durable bags made from non woven polypropylene (PP) and cotton bags.

Bag use
If the HDPE bag is used for what is called 'primary reuse' — when the bag is reused for shopping — then it will have to be reused fewer times to lessen its environmental impact. They can also be used in 'secondary reuse', which would be using the bag for things such a lining bins. The greater the combination of primary and secondary reuse, the lesser the carbon footprint of the bag.

The study showed that if the HDPE bag is not reused, then a paper bag must be used three times to have lesser impact, an LDPE bag must be used four times, a non-woven PP bag must be used 11 times and a cotton bag must be used 131 times. The number of times the bags must be reused goes up if the HDPE bag is reused as a bin liner.

Retailers have made a conscious effort to reduce their bag use in recent years, but the British Retail Consortium (BRC) welcomed this week’s study, saying the focus on the plastic bag was a distraction from other more important waste, such as food waste.

"We’re pleased to see the Environment Agency’s report acknowledges single-use carrier bags can have less impact than the alternatives," said Andrew Opie, BRC Sustainability director. "Yes, the plastic bag has become symbolic but this report confirms it is not the great environmental evil some would have us believe.

"Agonising over bags misses the point. There are much bigger targets supermarkets are helping customers to work on, such as reducing food waste," Opie said. "To obsess over bags distracts consumers from making bigger changes to their habits which would do more to benefit the environment."

Efforts to reduce bags
Between 2006 and 2011, retailers and customers cut the number of bags they used by 4.6 billion each year.

In December 2008, seven high street supermarkets and the Department of Environment, Food and Rural Affairs made a voluntary agreement to reduce bag use by 50 per cent compared to 2006 numbers. The stores nearly made their goal by reducing plastic bag use by 48 per cent.

The Republic of Ireland saw significant reductions in plastic bag use when stores began charging for them. Shoppers in Wales will have to pay for plastic carrier bags in stores from May 2011. In the UK, IKEA and Marks and Spencer charge for plastic bags, which has also helped them cut down on plastic bag use by 80 to 90 per cent.

While the efforts to reduce bag use are still important because of the resources that go into their production, the bags aren’t necessarily the most important target for reducing carbon emissions.  

"Efforts to cut down bag use will continue but they must not be the only focus," Opie said.