How long does it take for waste materials to decompose?

How long does it take for aluminum cans to decompose?

How long does it take a plastic bag to break down or a glass bottle to decompose? What about a milk carton or a Styrofoam cup?

Sources for rates of decomposition of litter (trash) on the web give you different rates. Once you’ve done quite a few of these searches, you realise that it boils down to about three different lists, all repeatedly quoted (but not always mentioned as the source):

1. The New York Times (Nemve E. Metropolitan Diary, October 1, 2001):
Paper- 2.5 months; Orange Peel- 6 months; Milk Carton- 5 years; Cigarette Butt- 10-12 years; Plastic bag- 10-20 years; Disposable diaper- 75 years; Tin can- 100 years; Beer can- 200-500 years; Styrofoam- never (immortal)

2. Penn State University*: Paper-2-4 Weeks; Leaves-1-3 Months; Orange Peel- 6 Months; Milk Carton- 5 years; Plastic Bag- 10-20 Years; Plastic Container- 50-80 Years; Aluminium Can- 80 Years; Tin Can- 100 Years; Plastic Soda Bottle- 450 Years; Glass Bottle-500 Years; Styrofoam-Never.
*This list is widely quoted, but I could never actually find the original source.

3. “Pocket Guide to Marine Debris,” The Ocean Conservancy, 2004*
Paper towel – 2-4 weeks; Orange or banana peel- 2-5 weeks; Newspaper- 6 weeks; Apple core- 2 months ; Waxed milk carton- 3 months; Plywood- 1-3 years; Wool sock- 1-5 years; Cigarette filter- 1-50 years; Plastic Bag- 10-20 years; Plastic film canister- 20-30 years ; Nylon Fabric- 30-40 years; Leather- 50 years; Tin can- 50 years; Foamed plastic cup- 50 years; Rubber boat sole- 50-80 years; Foamed plastic buoy- 80 years; Aluminium can- 80-200 year ; Disposable diapers- 450 years; Plastic beverage bottles- 450 year; Plastic beverage bottles- 450 year; Monofilament fishing line- 600 years; Glass Bottle- 1,000,000 years.
* Quoted in U.S National Park Service; Mote Marine Lab, FL and “Garbage In, Garbage Out,” Audobon Magazine, Spt/Oct 1998.

So what does all this mean, and how do we explain differences above?

Lets separate the first two lists from the third. People seem to have missed the word “ocean” in the source, and it stands to reason that degradation at sea for some materials would be different to that on dry land.

Then there’s some clear overlap between the first two lists, so it is likely the NY Times article was using the Penn State info to some degree, and topping it up from other sources.

Then a couple of further observations:

1. Plastic bags: Although all three lists above say it takes 10-20 years for a plastic bag to degrade, there are quite a few references on the Net saying that plastic bags actually take hundreds of years to degrade. So where does this discrepancy come from? Well, it seems that scientists don’t actually know the answer to that one, although the time it takes a plastic bag to degrade is obviously a lot longer than on the lists popularly quoted on the Internet.

2. Different rates of breakdown: It turns out that materials decompose differently depending on a lot of factors, including temperature, oxygen levels and many others. One important factor is the presence of water. Many landfill sites are hermetically sealed with plastic (and covered at night), so water doesn’t seep into the waste. Ohio State University has shown that adding water to waste sites increases their rate of decomposition. And of course material degrades differently in the ocean.

Context: Where does most household garbage eventually end up once it leaves the home? Clearly in landfills. That’s where the next set of stats should come from.

Happy recycling!


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47 comments on “How long does it take for waste materials to decompose?

  1. Pingback: All Things Eco Blog Carnival Volume Five | Focus Organic.com

  2. Mac Breneradal on said:

    That you very much what a great site! I have a french project to do on how long things take to decompost. It is amazing. I dont think we are going to have a earth to live on because people are not worring about it and yes you might not now but as a teen we are not going to live to see our grandchildren can everyone help it will be alot easier that way! Thanks for reading.

  3. hello on said:

    cooooooooooooooooooool

  4. dheyo on said:

    thanks for sharing…i m gonna put this info up at my office :)

  5. sheleiey on said:

    i can use some of this info for my science project! thnx

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  7. adriana marchi on said:

    that’s a very interesting site. i am developing a school project with my students about this subject. I hope they enjoy this site.

  8. Chloe on said:

    This is for my homework and I think I will get a gold star. Thanks!

  9. Soe on said:

    I was looking for these information for my research. Thanks a lot

  10. Rabecca on said:

    why doesn’t any internet sit have info on potato chip bags or polyolefin materials?

  11. Rabecca on said:

    i’m very unhappy because i can’t find my info

  12. leiling on said:

    thank u it is very helpful i think you put alot of effort on this awesome

  13. Elizabeth on said:

    This is unbeliavable! I mean I believe it but just… wow! I cant believe this! I’m going to recycle more than ever now that I know. I am not sure if i should send out paper fliers to some friends and family members and put some signs up in the street. I am not sure if I should but I am going to do it any way. Also, you people that made the sight might not know this, but did you know that having your computer on is wasting a lot of energy? well it is. I hope people recycle more. Well thanks for the information about this!

  14. pinkcheeks on said:

    i will use it for a lesson plan

  15. micheal jackson on said:

    Thank u so much now iwill own in science

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  17. gioliart on said:

    Thank you so much for this info. It will really help us desiminate information on waste segregation and to prohibit the use of styro and plastics in our community and eventually the whole country.

  18. hamishdsdssd on said:

    i agree we wont have a earth to live on. it is a sick mater we need to do somthing about it

  19. Kenny.A on said:

    if we don’t recycle things, we would be forced to live on other planets… (by the way, I’m looking for materials about this for a debate against other classes, so thanks for posting this ;)

  20. Thanks it is a great help, I’m now doing a research paper on how to resolve that problems and I hope many people will be aware with that figures on how long does it take before a plastic, carton, glass, aluminum or a Styrofoam to decompose.

  21. Thankyou heaps

  22. Eco-to-go!!!!!
    :) it’s a great alternative offered
    by many college dining halls in place of
    styrofoam to-go plates.

  23. What a fantastic source! Thank you!! This is always a focus of discussion when I speak to community groups and schools. Thank you for the summary and sources. It has always been my hope that educating the public of they damage they actually do when littering will be the best preventative.

  24. Laura on said:

    Thank you so much, this is gonna help me on my science project!

  25. harshad on said:

    hi, Dear Rabecca
    As indicated in further observations,it takes hundreds of years for plastc based materials including potato chips bags which are made from same material as plastic soda /beverage bottle in film form.

  26. Magicub on said:

    How do you measure that a diaper is going to take 450 years to decompose if we have been using diapers for maybe 75 years?

  27. Brooke on said:

    This helps alot for my science project on decomposition. It was a great attention getter! Thx!

  28. sheri on said:

    we all need to make a change !!!

  29. skip on said:

    Trying to get the school I work for to stop using styrofoam, very helpful!!

  30. aron rivera on said:

    i can use thiz for my sci project

  31. bobby on said:

    Thanks for this great insight

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  34. i am sooio gunna put thisz on facebook!!!!! thanx

  35. seeker on said:

    Even though you will all attemt to recycle and do the ‘right thing’, every minute of every day plastic continues to be produced to add to the already gowing plastic pile. Walk down your supermarket isle and count the number of goods contained in plastic. What you see will be there for generations to come… your childrens childrens children will be left with our rubbish. Tomorrow when you go and buy your water in a plastic bottle, or your soft drink, or your milk, or chips… what thought will cross your mind.

  36. bob on said:

    thanks for the information, i can use it on my english product :)

  37. I just wanted to let you know that this article was featured in my first blog post on http://dailygreentasks.tumblr.com/

    Excellent article!

  38. Pat C. Trii on said:

    SHANK YOU. VERY VERY MUCH. GO ECO-FRIENDLY-NESS!

  39. Thank you for all this information, it will certainly beneficial to my project. Tomorrow, it will be shown to the public and I hope they enjoy it because I have done my best.

  40. not wat i needed but still realy cooooollll

  41. l sherrill on said:

    a capri sun pouch. . how long does it take to decompose

  42. this is really helpful. thanks!!!

  43. kvick on said:

    its incredible how long it takes for these things to take place, and we have people all over the world who don’t know and don’t care. They may call us tree hugers but i’m a 17 year old who cares. I’m not a tree hugger but i’m definetly concerned! Thank you so much for this awesome info! :)

  44. Winston on said:

    Thank you for sharing this information to us. The world needs to see these facts to have a better understanding on that is happening in our present time. Many people don’t care but still there are few who attempt to make this Earth a better place for the next generations. Let’s just not understand these bits of information but also implant these in our hearts and minds! Good day from Philippines! :)

  45. Justin on said:

    I used too not care what happened to my old fishing string while fishing. After reading this I will be sure to properly dispose of it from now on. Thanks.

  46. cassian henrick m on said:

    guys,it is a serious issue,we ave to protect our environment

  47. jayson frias on said:

    this so important

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