Oxo-degradables and GreenBlue’s Not-So-Scientific Rooftop Lab

This article is by GreenBlue’s experimenters extraordinaire: Project Manager Adam Gendell and Project Associate Eric DesRoberts.

Back in August 2011 we serendipitously came across an oxo-degradable LDPE film wrap (for those of you who may not be enveloped in packaging lingo, that means it’s a thin piece of plastic with special additives that are activated under prolonged exposure to sunlight and oxygen to make the plastic film decompose into plastic dust, which may then be biodegraded by microbes).

Degradable plastic packaging like this is pretty controversial in the packaging community. In favor of oxo-degradable plastic is the argument that it will cease to persist in the environment if littered. Against oxo-degradables are arguments that the plastic dust is equally hazardous to human and environmental health, that they pose a risk to the plastic recycling stream because they downgrade the durability of the plastic with which they are mixed, and allegations that the degradability additives simply don’t work as advertised.

At GreenBlue we strive to maintain a level head and objective viewpoint, so we decided to conduct a scientific, on-the-ground (okay, on the roof) experiment to test the validity of the latter allegation that oxo-degradable additives don’t work. We did not measure the amount of sunlight and oxygen present, nor did we conduct multiple trials, nor did we use a non-degradable LDPE film as a control. What we did do is open a roof-accessible window in the GreenBlue office, place the film on the roof, throw some rocks on top of it to weigh it down, write down the date on which the “experiment” commenced, and proceeded to forget about it. About a week ago we had noted that 180 days had passed*, so we pulled it back in the office. It looked like this:

The film was definitely still recognizable as its original self, but noticeable fragmentation had indeed occurred. The film was brittle to the touch, and little bits of plastic ranging from quarter-size to dust-size were everywhere as pictured on the sticky note below.

Did we prove or disprove anything? Not really. We successfully littered little bits of plastic on the office roof, so we earnestly hope that they will continue to disintegrate until they are small enough to become a meal for some microorganisms. Our “test” results have suggested to us that this particular oxo-degradable additive works as advertised, and we threw it back out onto the roof for further observation.

It’s possible that the film may in fact disappear one day, but these authors remain skeptical that degradable plastics are a step in the direction of sustainability. After all, that LDPE film was likely made from petroleum resources, of which we only have a limited (and coveted) quantity. Can we find other ways to combat litter so that we can keep that valuable material from becoming dust in the wind?

* 180 days is the standard amount of time in which a compostable plastic is required to disintegrate completely, but oxo-degradable plastic is not intended to be compostable. Oxo-degradable manufacturers acknowledge that the time period necessary for total disintegration is considerably longer than 180 days, so it should not be expected that the film was supposed to have disappeared when we pulled it back in the office.

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