A plastic fantastic mess

Posted on August 20, 2009 by A Free Man


Courtney’s post on the proposed plastic bag surcharge in Seattle got me thinking about these ubiquiotous flimsy ‘flags of the consumer era’. Here in South Australia, a total ban on light weight plastic shopping bags was enacted back in May. It has been, in large part, a popular measure and these days nearly everyone in the city center can be seen carrying around reusable canvas shopping bags as well as their briefcases and backpacks. Anecdotally, there seems to have been a notable reduction in the amount of plastic bags strewn all over our fair state – certainly the biggest bonus of the ban.

But I’m The Greenists science guy and thus tasked not with telling happy stories of litter free Australian countryside, but with breaking down the facts. So, I wanted to take a look at the science surrounding consumer packaging. Are these bags as bad for the environment as we think? Are they really clogging our waterways and choking wildlife? What is the most environmentally beneficial alternative?

There are two main types of plastic bags used in the retail sector – the bags that we commonly take our groceries home in, and those that are vilified by environmentally conscious consumers, are made from high density polyethylene (HDPE). The heavier weight bags that you get from clothing shops are made from low density polyethylene (LDPE). Both materials are made from ethylene, a by product of oil refining and thus a non-renewable resource and therein lies one of the biggest issues with these bags. According to a report produced for Environment Australia by Nolan-ITU Pty Ltd, the fuel consumed by driving a car 1 km is equivalent to that used in making 8.7 HDPE bags. So, yes, plastic bags have a relatively high energy cost. However, the current alternative – paper bags – are actually worse in terms of energy consumption. The same report estimates that making plastic bags uses 40% less energy, produces 80% less solid waste, 72% kess atmospheric emissions and 90% less waste than making paper bags. Despite being made of a renewable resource, paper bags are actually worse for the environment.

This does not make plastic bags the environmentally friendly option. HDPE bags take an estimated 200 to 1000 years to break down, which means they’ll be festering away in our expanding landfills long after we ourselves have broken down. And as they slowly decompose, many of these bags are oozing toxic heavy metals. A report prepared by the Toxics in Packaging Clearinghouse for the U.S Environmental Protection Agency in 2007 found that 16.7% of plastic shopping bags tested contained unacceptable levels of mercury, lead, chromium or cadmium – mostly in inks that were used to print the bags. A 2009 update found some improvement, with only 9% of HDPE bags decorated with ink containing toxic heavy metals.

Another problem with plastic bags that is often cited by opponents is that they are responsible for a virtual marine genocide. An oft cited figure, one that has been roundly debunked by the scientific community, is that plastic bags are responsible for the death of 100,000 marine animals and one million seabirds. The shocking figure stems from a Canadian government study commissioned in 1987 to look at the effects of fishing debris on marine wildlife. The Canadian report was focused on plastic debris from synthetic nets, fishing lines and the like, not plastic shopping bags. There have since been a number of reports describing whales, dolphins and other marine life that have choked to death on plastic debris, but again these are not attributed to plastic shopping bags. With the exception of anecdotal reports and photographs, I was unable to find a legitimate report of a marine animal that had been killed by a plastic shopping bag. I don’t like the things either, but they are not responsible for killing hundreds of thousands of turtles. That is just junk science.

That being said, plastic shopping bags definitely make their way into the marine ecosystem. Of the 500 billion to one trillion HDPE bags that are consumed worldwide every year, only 1% of them are recycled. The bags are extremely difficult to recycle and are mostly downcycled into decking material and other non-recyclable items. It would seem like good news that only 1 – 3% of bags find their way into the ‘litter stream’ - however that means that 5 – 30 billion bags a year go wafting around our streets, rivers and oceans. We know that there are great islands of garbage out in the Pacific Ocean, manmade masses of junk in which there is more plastic particulate matter than there is plankton. I’ve been unable to find a legitimate estimate of how much of the garbage in the Gyre is plastic bag waste, but 80% of the trash in the ocean originates on land and a majority of that is from consumer products.

What have we learned? There is no damning scientific evidence to warrant outlawing or taxing plastic bags. However – and it pains me to say this – science sometimes doesn’t tell the whole story. I’m a big fan of the SA bag ban, not for scientific reasons but for aesthetic ones. For society, there are bigger issues with plastic bags, the most obvious of which is litter. Plastic bags are a very visible and unsightly component of litter. While things like cigarette butts are more plentiful, plastic bags are more of an eyesore. I challenge you to walk one city block and not find at least one discarded plastic bag flapping in the breeze. They are everywhere – wrapped around street signs, hanging from the trees, floating ghostly through creeks and streams, and dotted along beaches.

Even if you don’t mind your neighborhood being soiled with errant plastic bags, there is a cost associated with litter cleanup. The State of California estimates that they spend $375 million per year cleaning up litter in the State. Similarly, Australia spends $200 million a year on clean up, a figure that the State of South Australia hopes to cut significantly behind the bag ban.

It isn’t just the cost of litter cleanup. Plastic bags cost retailers money – up to $4 billion a year in the U.S. You can be fairly certain that cost is being passed on to you and I when we get to the till. The South Australian government estimates that the bag ban will save consumers $10 to $15 per year – a modest amount, to be sure, but that is $10 – $15 per year on something that at best I use to pick up after my dog and throw in the bin.

Let’s assume that I’ve convinced you, gentle readers, that a ban is the way to go and talk alternatives. Paper is, in many ways, worse than plastic. There are concerns about the new compostable (or bioplastic) bags as well. These bags are made from corn or soy and may contain harmful chemicals. Biodegradable plastic bags are usually made of HDPE but include an additive that causes the plastic to break into smaller and smaller pieces when exposed to light and oxygen. This is an extremely slow reaction and thus not much of an improvement over the non-degradable bags. Both compostable and biodegradable bags cost five to seven times as much to make as HDPE bags – a cost that would no doubt be passed on to the consumer.

In my non-scientific opinion, the best alternative is a ban or heavy surcharge on plastic bags. It is too early to generate data on the South Australian ban, but the so called Plastax in Ireland (a 15 cent surcharge for bags) has resulted in a 95% reduction in their use without a collapse of the Irish consumer economy. There is a truly green alternative to plastic bags, paper bags and compostable plastic bags – reusable bags. Yes, they are inconvenient. Yes, sometimes they are forgotten at home and you end up buying more at the supermarket. Yes, they cost you money. But, you see a lot fewer canvas bags littering the highways and byways. But green isn’t always convenient. Plastic bags are a convenience item and certainly not a necessity for modern life. I and a million or so other South Australians are walking evidence that you can get by pretty well without plastic shopping bags. How do you like that for scientific data?

Image from Inhabitat.


  1. Great post as always, A Free Man. It surprises me to hear that paper bags are more harmful than plastic ones in many ways.

    Yes, there are so many reasons to get rid of plastic bags altogether. I’m glad to hear the ban works well in places like Australia and hasn’t resulted in mass chaos. After all, we’re not talking about major lifestyle changes here; just a different way to carry groceries from your car into your house. A minor thing, for sure.

    August 20th, 2009 at 11:37 am
    Comment by Courtney
  2. [...] Allie’s Answers new today, filling my role a as resident science guy. I’m looking at the contentious science surrounding plastic shopping bags today. Head on over and have a look and check out the rest of The Greenists as [...]

    August 20th, 2009 at 5:49 pm
    Pingback by When I was younger I thought I knew everything. Now I’m older I know I know everything. | A Free Man
  3. A lot of people like to think that they are getting their plastic bags for “free” (thus if we ban them consumers lose). I think I used to have this attitude (if I don’t get plastic bags for free when I shop, I’ll actually have to buy plastic bags for garbage, poop and what-have-you).

    Good point that this is actually a cost passed onto the consumer.

    August 20th, 2009 at 10:22 pm
    Comment by zayzayem
  4. If only we could get the conservatives to see this from a selfish point of view, I think we might make some headway in the U.S. Ultimately it affects quality of life for human beings. Certainly in the aesthetic sense, but also health-wise. I don’t care about marine animals dying, until it becomes apparent that the reason they are dying might have an effect on me also. I really began to wake up to what we are doing when I moved to a pastoral setting in the country — and found my air and water polluted by industry miles away. I became sensitized to it, seeing it everywhere, and realized that we are very much like the frog in the pot of heating water. It’s happening slowly enough that people don’t realize what has been lost, what we are losing.

    As for the ban or surcharge, here we don’t have it, but it seems to me to have been very effective for major chain stores to simply put up signs saying “bring your own bags!” Not too long ago I would bring my own bags and the checkers would be hostile about it; naturally if people are socially discouraged about something they won’t be inclined to do it. Now that it’s officially approved by the management, there’s an air of justification about it which makes it much easier to do.

    August 22nd, 2009 at 1:54 pm
    Comment by Linda
  5. Regarding the issue of plastic bags, I am posting this in an attempt to get some helpful suggestions- I also posted something over at my blog, but maybe a reader of this post can help me?

    I live in the city and have two dogs. Two dogs that poop. Being a good resident and neighbor, I pick up that poop. Normally for that purpose, I use the plastic bags that I get from the store, or that my parents get (they give me their extra for that purpose)- so I’m re-USING, but not really re-CYCLING since in the end the bags still end up in the trash. The greenest option for shopping is of course the re-USABLE bag- but reusable bags don’t help me pick up and dispose of poop.

    I would really appreciate any suggestions on what is the greenest way to clean up after one’s pet. Just to give you an idea of what I have to work with, I live in a small row house with a tiny backyard, so space is at a minimum. I’ve seen biodegradable poo bags, but are they truly ‘green’?

    Please leave me comments if you have any ideas for me. I would really appreciate any insight and would like to make whatever earth-friendly change I can while dealing with a daily chore.

    August 25th, 2009 at 12:25 pm
    Comment by Hope
  6. Hi there. You wrote, “With the exception of anecdotal reports and photographs, I was unable to find a legitimate report of a marine animal that had been killed by a plastic shopping bag. I don’t like the things either, but they are not responsible for killing hundreds of thousands of turtles. That is just junk science.”

    I just wanted to direct you to a site that is currently collecting images of sea turtles that have swallowed plastic bags and other plastic objects. Check out this link:

    a href=”http://www.seaturtle.org/cgi-bin/imagelib/index.pl?si=&stype=1&thumb=1&perpage=28&sort=3&cat=663&user=”>http://www.seaturtle.org/cgi-bin/imagelib/index.pl?si=&stype=1&thumb=1&perpage=28&sort=3&cat=663&user=

    I realize it’s not proof of numbers, but I have spoken with marine biologists who have witnessed marine animals harmed by plastic bags.

    But I agree with you that paper bags are not the solution either. Bringing our own bags is the way we need to go!

    August 26th, 2009 at 10:50 pm
    Comment by Beth Terry
  7. Oops. My link did not work. Trying again:


    August 26th, 2009 at 10:53 pm
    Comment by Beth Terry
  8. Isn’t ethylene also produced by apples as they age? It’s part of the ripening process, how flowers open, etc. I wonder if the presence of the bags in the natural environment has any effect as the materials age.

    September 30th, 2009 at 10:14 pm
    Comment by mattmc

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