When I posted about my disappointment with Alastair Darling's plans for a plastic bag tax, all sorts of responses came in arguing that this was an excuse to introduce a tax; that plastic bags should be celebrated for their lightweight durability and that they are a necessary part of modern life. I'm afraid I don't agree.

It's easy to recycle them
That's rubbish. Rarely collected by local authority kerbside collections (tell me if yours does, I'd love to know what it does with them), your best chance is to find a supermarket with a recycling bank for bags. But this is far from ideal. The UK lacks its own developed plastic recycling facilities so, like most of Europe, sends the majority of its plastics to China to be recycled over there, an arrangement which lead to a BBC Real Story scandal two years ago. It uncovered our plastic being piled into Chinese landfill rather than being recycled. The problem with the plastic used in bags is that it is low quality: cheap to make from new, but tricky and energy intensive to recycle. Look at most plastic items and you'll see a triangle containing a number; the higher that number the harder the product is to recycle. PET, numbered one, is the best sort for recycling. Decent carrier bags are numbered four. The more lightweight variety can be as high as seven. For more info on these codes, see here.

They only take up a tiny proportion of landfill
Taking up landfill space has never been one of the main accusations levelled at plastic bags. That they are made from a non-renewable resource, yes. That each of us in the UK uses an average of 290 of them every year, definitely. Not to mention the impact they are having on the natural world - see here. But taking up landfill space is only a small concern. In fact, it is worrying itself that only an estimated third of the bags we use end up in landfill when we are getting through so many - 145 billion last time I looked here. Where are they if they're not in landfill? As they can't all be in your special plastic bag holder. Many seem to find their way to the sea. There has been debate recently about the extent to which plastic bags cause marine deaths. The plastic industry points out that many of the numbers quoted are based on estimates with little scientific support. What has clearly emerged from this debate is that plastic bags are only one kind of plastic that threatens animals, and probably not the worst. Damage done by solid lumps of plastic is even more serious.  Reports suggest that many birds can die because they ingest enough small lumps of plastic that their stomachs are filled with nothing else and they starve to death.

They don't take long to breakdown
The fact is that no one knows precisely how long a plastic bag takes to disappear without digging one up every decade to see how it's getting on. Few scientists have given a figure of less than 100 years; most estimate between 200 and 1,000 years, depending on whether the bag finds itself buried in a light and air deprived landfill site or up a tree, where sunlight will help to break it down. A few weeks ago, the Association of Plastic Manufacturers at the Cyprus Chamber of Commerce and Industry, claimed that:
"They decompose within one and a half to two years because of ultraviolet
sunlight." I would love to know where that figure came from.

They require less energy to manufacture than paper bags
In part this is true, but paper bags are not the only alternative to plastic bags, and while they require more energy, they also come from a renewable resource. Paper bags made from fibres from sustainably managed forests, or even better, recycled paper are environmentally superior to an oil based product. It takes 430,000 gallons of oil to produce 100 million plastic bags, according to Worldwatch Institute. In short, paper may consume more resources to produce, but it is more recyclable than plastic, breaks down more easily and does not come from oil, a resource that we should be decreasing our reliance upon.

They are durable and reusable
True, it has been claimed by the plastic industry that a bag can be used 15 times to carry shopping before it falls apart. This is the theory, but how many of us do this? They have become a one-use disposable item because we know the shop will hand out more for free, next time we go. The ten billion bags handed out to British shoppers are used for an average of 12 minutes before they are discarded. A material bag that you paid for is more likely to accompany you to the shops countless times. In the wake of I'm Not a Plastic Bag fever, scores of bags have followed, made from every imaginable material ' from jute, hemp and bamboo to corn starch, string, recycled paper and even banana leaves.

Yes, there is an energy cost in the production of these, but the idea is that this is negated if you use them enough times. And of course, the habit of using something time and time again - whether this is a bag, a cloth in the kitchen or an item of clothing - is simply good environmental practice.