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Letter to Editor
OXO-BIODEGRADABLE PLASTICS ASSOCIATION
Sir, My attention has been drawn to a letter in your Journal on May 2nd from Jim Lunt about oxo-biodegradable plastics.
In summary, oxo-biodegradable plastics will degrade, then biodegrade, in whatever timescale is required on land or sea, light or dark, heat or cold, leaving no methane, and no harmful residues.
Mr. Lunt is clearly not aware of the scientific evidence published in peer-reviewed scientific journals and in many standard texts reviewing the evidence. He appears to be a technologist who must see micro-organisms actually growing on oxo-biodegradable plastics before he can accept that they are biodegradable as well as just degradable. If so he can find a graphic demonstration in my edited book Degradable Polymers: Principles and Applications, Kluwer Academic Publishers, Chapter 3. This chapter also describes the underlying science of oxo-biodegradability.
Dealing with what happens to oxo-biodegradable plastics in landfill. It is important to understand that, since they depend on oxygen to degrade, they disintegrate rapidly in the surface layers into particles that are harmlessly inert in the depths of the landfill where the air has been displaced. The contribution of degraded plastic packaging to the volume of a landfill is minimal.
It is not beneficial to the environment that plastics should anaerobically biodegrade in landfill, because they emit methane, which is a powerful greenhouse gas. This is one of the many problems with crop-based plastics, as well as with cotton, paper, and jute.
Another problem is the use of scarce land and water resources to grow crops to make plastics, which should be used for food production.
In the aerobic conditions of the normal environment, including the oceans, oxo-biodegradable material biodegrades like nature's waste lignocellulose, and contributes to the fertility of the soil by the formation of cell biomass.
I should be pleased to provide further information on the science of oxo-biodegradation of plastics, and would suggest that interested readers look at www.biodeg.org.
Yours sincerely,
GERALD SCOTT DSc, FRSC, C.Chem, FIMMM
Professor Emeritus in Chemistry and Polymer Science
Aston University, United Kingdom
Chairman of the Scientific Advisory Board of the Oxo-biodegradable Plastics Association
Co-chairman of the British Standards Institute Panel on Bio-degradability of Plastics
Scientific Advisory Board: Professor Gerald Scott (UK), Professor Emo Chiellini (Italy), Professor Jaques Lemaire (France), Professor Norman Billingham (UK), Professor Ignacy Jakubowicz (Sweden), Professor Telmo Ojeda (Brazil), Dr. David Wiles (Canada).
The Editor
Exchange Morning Post
Canada
editor@exchangemagazine.com
FROM Professor Gerald Scott, DSc, FRSC, C.Chem, FIMMM
May 8 2008
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