Why do plastics take so long to break down in landfills?



  1. 0 Votes

    Scientists test the time it takes to break down an item with a respirometry test.  This test takes a solid waste sample and puts in a compost mixture to test how long it takes a sample to break down.  From the resulting break down, scientists can measure the levels of CO2 given off by the decomposition process. 

    When a plastic bag is put through one of these tests, no CO2 is recorded which means microorganisms are not biodegrading plastics.  The reason for this is that plastics come from a man-made polymer called polyethylene, which soil microorganisms do not recognize as food.

    Though microorganisms will not break down plastics, they will eventually degrade through a process called photodegrade.  Ultraviolet radiation from the sun will, over a long span of time, break the bonds of the polymer and the bag will degrade into tiny particles.  This process can take hundreds or even thousands of years.

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