The Rann government’s ban on lightweight plastic shopping bags starts today. I predict chaos and frustration at supermarkets around the state.

Tim Blair notes that the people who grow marijuana are subject to a fine of $300, while those who provide their customers with a plastic shopping bag are subject to a fine of $315.

This is a letter I wrote to my local paper about this late last year. ‘The Islander’ is the Kangaroo Island paper. The arguments still apply.

I am all in favour of more thought about environmental issues, including the use of plastic shopping bags.

Thinking without acting is pointless, but acting without thinking is dangerous.

A basic level of thinking is ensuring that one has one’s facts correct. Bernard Baruch once said “Every man has a right to be wrong in his opinions. But no man has a right to be wrong in his facts.” Those who undertake to change public policy have a special responsibility to ensure they present their case fairly and without distortion.

This is one of the reasons I have become concerned about the debate over the use of plastic shopping bags.

Three weeks ago the front page of The Islander claimed that the government was going to ban single use polypropylene bags. This claim was repeated on page nine of the November 6th edition: “Old Bags Day is about shoppers saying no to single-use poly-propylene bags.”

I would wholeheartedly support a ban on single use polypropylene shopping bags. Polypropylene is a tough plastic which does not easily break down.

There is only one problem. The government is not proposing to ban single use polypropylene shopping bags, because single use polypropylene shopping bags have never been available in Australia. What the government is proposing to ban is light-weight polyethylene bags.

I was astonished to see, also in the November 6th edition of the Islander, a photo of a shop employee putting a product packaged in plastic into a reusable bag printed with the words “Put an end to plastic bags.”

This is almost beyond parody, given that the bag with these words printed on it is made of a highly durable plastic – about fifty times as much as plastic as a light-weight shopping bag. Just as astonishing was the caption “x  (the shop assistant) packs a reusable bag instead of using plastic.” No, the reusable bag is made of plastic.

Imagine this conversation. “So you’re going to ban light-weight plastic shopping bags to benefit the environment. Sounds great! What are you going to replace them with?”

 “Well, instead of giving people light-weight bags made in Australia, we are going to sell them bags which contain about fifty times as much plastic, of a type which takes much longer to break down, and which are made in China.”

“Oh.”

The argument is that because they last longer, re-usable plastic bags will in eventually result in less plastic waste.

The state government, on its Zero Waste website, thoughtfully tells us that its calculations of the environmental benefits of the ban are based on the assumption that one reusable polypropylene plastic bag will replace ten ordinary light-weight plastic bags each week for two years. Does this strike anyone else as manifestly ludicrous?

This means that if you take home ten bags of groceries and other products each week, the government’s case for banning light-weight bags is based on the assumption that from now on you will take all those groceries home in a single reusable “green” plastic bag.

A more reasonable estimate would be that each reusable plastic bag will replace two light-weight shopping bags a week for six months. At the end of the six months the total amount of plastic used is about the same.

But instead of light weight polyethylene mixed with starch or oxidising agents, which breaks down over 12 to 18 months, you are left with a dense mass of polypropylene which may take up to 1000 years to break down.

But it gets worse. Once ordinary shopping bags are replaced by denser reusable plastic bags, people will have to buy other plastic bags; bin liners, dog poo bags, nappy bags, etc to replace the light-weight shopping bags they used to re-use for those purposes. The end result is more plastic waste, not less, much of it a harder plastic to dispose of.

People are right to be concerned about the impact of plastic waste on wildlife. Plastic shopping bags are a very small part of this problem. Of course any wildlife lost to plastic bags is unacceptable. But it doesn’t necessarily follow that the best solution is to ban them, any more than rusting car bodies left in the bush is a reason to ban motor vehicles.

Instead, we should ensure that litter regulations, and the already stringent international laws banning the disposal of plastic at sea to which our government is a party, are rigorously enforced.

Don’t be bullied into a “solution” which is inconvenient, more expensive and offers no benefits to the environment.