Study Shows Many Additives Designed to Biodegrade PE, PET Don't Work
23. February 2015
A recently-released study from Michigan State University indicates that many additives that claim to break down PE (i.e., plastic bags) and PET (i.e., soda bottles) simply do not work in common disposal situations such as landfills or composting.
Featured in the current issue of Environmental Science and Technology, are a culmination of a three-year study that focused on five additives and three categories of biodegradation, which cover the majority of methods available on the market today. The team studied biodegradation with oxygen, such as composting; biodegradation without oxygen, such as anaerobic digester or a landfill; and simply burying plastics.
“There was no difference between the plastics mixed with the additives we tested and the ones without. The claim is that, with the additives, the plastics will break down to a level in which microorganisms can use the decomposed material as good. That simply did not happen,” says Rafael Auras, co-author and MSU packaging professor.
William Rathje, the late Arizona paleontologist and founder of the Tuscon Garbage Project, revealed that even after years underground, chicken bones still has meat on them, grass was still green, and that even carrots still maintained their orange color. Since organic materials take so long to decompose, it’s not surprising then that plastics, even with the aid of additives, would take decades or longer to break down, if at all. So, if the additives don’t work, what’s the solution? Says Susan Selke, co-author of the study and MSU packaging professor, “The solution is not to make claims that are untrue. The proper management of waste plastics is the proper management of waste plastics.” And, for now, that means not using any of the disposal methods or additives included in the study as feasible option, she adds.
The study was funded by MSU’s Center for Packaging Innovation and Sustainability. Noted Selke, “Package-use companies funded this study because they wanted to know if the additives that are being marketed to them work. They wanted scientific proof to evaluate the products and disposal approaches that are available to them to break down plastic.”