Space City Skeptics

The Official Blog of the Houston Skeptic Society

Paper or Plastic?

with 7 comments

(This is a brief overview of the manufacture of paper and of plastic, and is not intended to be comprehensive, or a chemistry class.)

How do you answer?  If you give what you think is the ‘correct’ answer, you say ‘paper’ or you’ve brought your own bags.  Let’s examine that choice.

The paper bags used in grocery stores begin in the forest, with the timber industry.  Even though trees are a renewable source, there is more to producing new paper than planting new trees.  The paper industry is one of the dirtiest industries around.   The chemicals used in the paper pulp process include sulfur, bleaches, and acids.  The process uses huge quantities of water, which must be treated and cleaned, a process which also uses chemicals.  According to a representative of the Texas Commission on Environmental Quality, paper manufacturing also receives a larger number of complaints than refineries on ‘nuisance odors ‘ which is a term meaning that the facilities emit very strong, disagreeable odors, as unpleasant to live near as a feedlot.   Processing facilities must control odors to the same extent that they must control pollutant emissions. Odor is a non-trivial pollution problem.

Paper has a limited ability to be recycled.  On each trip through recycling, paper must be chopped and shredded, which shortens the fiber length.  Eventually, the fibers become too small to use and must be discarded into landfill, as do many of the manufacturing byproducts from paper manufacture.

What about plastic?  Grocery stores bags are made of polyethylene, which begins as the ethane component of natural gas.  The primary emission from polyethylene manufacture is from natural-gas fired heaters, which supply heat or steam for the process.  Natural gas is the cleanest burning fuel, and natural gas wells are clean and low-profile – a valve sticking up out of the ground as opposed to the ‘pumping units’ associated with oil wells.  The conversion of ethane into polyethylene is close to 99% efficient.  The feedstocks for ethylene are basically ethane – clean and odorless, and steam.  Additionally, polyethylene can be recycled almost infinitely.  Even though the molecular weight of the polymer chains will change with recycling, it’s still plastic and can be reused.   It is also inert- in some locations, polyethylene has been chopped into sand-sized bits and incorporated into heavy clay soils, to lighten them as you would do with sand.

The manufacture of polyethylene requires about 6% of the water that paper manufacture requires.  As our population grows and the supply of fresh water becomes increasingly scarce, industrial usage of water becomes an important consideration in the chain.

Transportation adds more cost to the paper product than to plastic.  Paper is heavier, so trucking costs, for a given ‘carrying capacity’ of the bag, are higher, as is the amount of pollution from the gasoline needed to transport the denser product.

Frequently, the public’s attitudes and beliefs about environmental consequences of our choices are shaped by sound bites and pictures from the media.  Pictures of sea turtles with a plastic grocery bag stuffed into their throat, or a sea mammal with a set of six-pack rings caught around its head, are moving and emotional.  These items do end up in the oceans, due to sloppy handling.  However, legible newspapers from 70 years ago have also been mined from landfills. Searches on the EPA’s website will turn up studies showing that the TOTAL environmental impact from the manufacture and long-term landfill storage of paper bags exceeds that of plastic bags – from the mining of the raw materials (trees or natural gas), through manufacture including energy requirements, pollutants, water use, and hazardous wastes, to the volume of a bag in the landfill.

As skeptics, we must look at the entire picture.  The issue is more complicated than I can discuss in a short blog post, but critical thinking skills can be used on these issues just as readily as they can on issues of quackery and pseudoscience.   I posted this article in a slightly different format on a well-known skeptic website a few months ago, and was attacked for either being a shill for Al Gore or a shill for Big Oil. I’m not sure how I can be both at the same time, but it shows the knee-jerk reaction of people on hot-button issues.  Although most people wanted to disagree with my statement that plastic is a better choice (as compared to paper), the only evidence given was that sometimes “bags end up in the ocean and get caught on bird beaks or swallowed by whales”.  This is true, but the answer is not to ban plastic over paper, but to handle any bag properly through reuse, recycling, and proper disposal.

The option with the least environmental impact is to carry reusable shopping bags, or carry personal bags.  However, if you are faced with a choice between paper or plastic, plastic is the environmentally responsible decision.

Written by Geek Goddess

May 26, 2009 at 4:02 pm

7 Responses

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  1. Yes, and the debate over disposable diapers plays in here too. Phosphates in the water and energy cost versus plastic and poop in the landfill. I suppose that’s why the “no diaper” movement came into being. But most people have their minds made up one way or another on environmental issues, and don’t go stepping on their cherished and noble ideas!


    May 27, 2009 at 11:42 pm

  2. We just lay down newspaper.


    May 28, 2009 at 12:08 am

  3. I think if you live in a place with scarce water and lots of land, disposable diapers are better, but if you have plenty of water and no landfill, cloth diapers. That being said, I am just old enough to remember my nephews having cloth diapers with plastic waterproof pants to go over them, dealing with the dirty diapers which have to be washed off in the toilet, etc. An old friend who was a pediatrician said that diaper rash was endemic with cloth diapers, and that allow babies still get diaper rash, the incidences greatly decreased when people stopped using cloth diapers.


    May 28, 2009 at 5:09 am

  4. Oh, absolutely. The diaper rash was terrible, the plastic pants LEAKED when you used them and scalded the bottoms when left on too long. And you haven’t lived until you have dealt with dirty cloth diapers. Rinsing off the poop, then soaking the diapers, then washing with detergent strong enough to get them clean but gentle on baby’s bottom, rinsing completely, drying, the SMELL in the house, and trying not to run out!! Those were NOT the good old days. Disposables now are so wonderful – take it from an OLD hand!


    June 1, 2009 at 10:33 pm

  5. I’m as much of an old hand at cloth diapers and diapering as anyone I know is, and I’m always taken aback whenever I come across articles and comments related to cloth diapers/cloth diapering in general.

    If it’s not rubber pants and diaper pins at the forefront, then it’s the rinsing, the washing, and the folding. If people spent more time promoting the use of cloth diapers and all related necessities surrounding cloth diapering–rather than demoting them, more mothers would choose cloth diapers.

    I never found it to be a problem rinsing out a dirty cloth diaper in the toilet, before depositing it into the plastic diaper pail. It took but a minute, and was all part of the process of saving money as well as the environment when I was cloth diapering my children.

    I used rubber pants 24/7-365, and never did any one of my children suffer a scalded bottom or chronic diaper rash as a result of. When change time reared it’s head, I could usher off a child’s pair of rubber pants in seconds, unlatch the pins holding the diaper, remove, clean, and re-diaper the baby in question, replace rubber pants, and baby was back in business again–often in under 2 minutes.

    No smells in the house, no inconvenience of line drying them on laundry day, and for surely no ridiculous expense and waste that disposable diapers bring. It’s time people realized what throw away is costing us and our environment.

    Mary Ellen

    June 16, 2009 at 2:12 pm

  6. You have valid points, but in some parts of this country, there are serious water shortages, so the washing of diapers in a given city would have a larger environmental impact that a place that has plentiful water but no landfill.

    I will try to find the EPA study and post it here.

    Geek Goddess

    June 16, 2009 at 2:18 pm

  7. Please do Geek Goddess. All things environmental are good.

    I fully understand water shortages across the land, but relying solely upon non-renewable resources and wastefulness is not the answer either.

    I am not looking for any sort of argument pertaining to this age old debate, however I always view a little constructive back and forth as being positive.

    Mary Ellen

    June 17, 2009 at 11:33 pm

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