How GREEN is your shopping bag

Its estimated that only 2 per cent of plastic bags are in fact recycled. Where does that leave the reusable 'green' bags?

Single-use plastic shopping bags were introduced in the 1980s and we continue to use massive numbers of them - around 1 billion a year in New Zealand believe it or not. Over 40,000 plastic bags are dumped in landfills every hour and around 16 million of them a year end up as litter in the sea, on beaches, streets and parks and they take between 15 and 1000 years to biodegrade.

The Warehouse charges for dispensing plastic bags but huge numbers of retailers don't - including supermarkets which are arguably the greatest users. Nearly four years ago Foodstuffs introduced pay-to-use on plastic bags but because other supermarket chains didn't follow suit they were forced to withdraw the initiative to remain competitive in an industry that operates on narrow margins.

David Hannan, owner-operator of New World in Kerikeri, says legislation forcing supermarkets and other retailers to reduce the use of plastic bags would place everyone on an equal footing. As a community incentive New World Kerikeri counts the number of reusable bags brought in by customers and then donates 5 cents per bag to the committee raising funds for a covered swimming pool in the town. Around $5,000 has been bestowed to date.

The reusable 'green' bags are often provided free-of-charge by supermarkets but how eco-friendly are they? Some critics suggest the only thing green about them is the colour and their value lies in the fact they last longer and can carry more items than a plastic bag. According to Gmagazine Australia, if a household buys 70 items of groceries each week for a year they'd use 520 plastic bags in that time. The same purchases for the same period require just 4.15 reusable bags which can last 104 trips, or two years, before they need to be replaced. The plastic bag is generally one-use - before being used as the ubiquitous domestic bin liner and thus ending up back in the landfill.

Although plastic bags are recyclable they are often excluded from council recycling systems because they get caught up in the machinery. It's estimated that only 2 per cent of plastic bags are in fact recycled. Like their plastic cousins the reusable bags are made from non-renewable fossil fuels and the removable base is manufactured from nylon or PET - another plastic.

The majority of reusable bags, 99.5 per cent, end up in landfill. Only the material is recycled, the stitching and the base is not which makes the recycling process labour-intensive and costly. What the 'green' bag doesn't do is float away on a breeze like plastic bags that end up in waterways, clog up storm water and outlet drains or escape to the sea. Wind-born plastic bag infestation is so prolific in some countries they're called the national 'flower' as they hang from tree branches or infiltrate fence lines.

In the end, the multi-use bag out-weighs any downsides. To be greener still, a hemp, jute or organic cotton bag is by far the best choice.

- Sandy Myhre