His comments follow a recent law suit against three US companies, which prompted UK oxo-bio firm Symphony Environmental to criticise the state’s marketing laws that prohibited its customers from describing plastic products with a destructive additive as biodegradable.
Scott, who is also emeritus professor of chemistry and polymer science at Aston University, told FoodProductionDaily.com:“Doubtless you’ve realised that the US legislation has been prompted by the bioplastics industries.”
He added:“[They] see their market decreasing due to the scientifically based evidence on the effectiveness of the much cheaper oxo-biodegradable plastics.
Breaking-down the polymer
Oxo-bio additives are defined by the OPA as transition metal ions of cobalt, iron or manganese, which it said should not be confused with toxic heavy metals: lead, mercury, cadmium and chromium, which are not used.
Their oxidation and disintegration involved the “pro-degradant additive” breaking-down molecular chains within the polymer, but only when oxygen was present, Scott said.
This would only occur in an open environment, or in the upper layers of landfill, Scott added, but deeper down in landfill (in anaerobic conditions) he said that the process stopped and the undegraded oxo-bio material would not emit methane.
He added: “This is important, because methane is a greenhouse gas 23 times more powerful than CO2. By contrast, ‘bio-based’ hydro-biodegradable plastics do emit methane in anerobic conditions.”
Scott said that oxo-bio plastic degradation only required oxygen (although heat and light accelerated the process), with the time taken for polymers to reach a molecular weight of 5,000 Daltons (from 250,000 at the start) would “normally be less than 6 months”.
Timetable for legislators
He said:“This is the timetable on which legislators need to focus, because the material then no longer be a plastic – it will have lost its strength and will no longer be capable of entangling wildlife or blocking drains.”
“It will not by that time be visually intrusive, and it is not toxic. Testing of oxo-biodegradable plastics includes a standard OECD test [an international standard for chemical testing] to demonstrate non eco-toxicity,” Scott added.
Reacting to the Californian suit, ENSO Plastics vice president Del Andrus told this publication that the company (as a defendant in the suit) had had to combat a sustained mis-information campaign that had influenced legislators.
He said: “What this Californian issue shows is the need for more education and understanding of innovations that can help our environment…the need for less manipulation of the regulatory process to create anti-competitive laws that perhaps only serve to allow one material [compostable plastics] to make environmentally friendly claims.”
Andrus added:“The science behind the ENSO technology has been consistently tested and scrutinized by many certified independent testing labs.”
Asked what research had been done, he cited Georgia Tech Research Institute, which recently announced research led by Lisa Detter Hoskin – including work using ENSO’s bottles – into the use of additives to trigger plastic biodegradation.
Georgia Tech research
The institute said it was working with the Plastics Environmental Council (PEC) to expand the use of chemical additives that caused polyethylene, polypropylene, styrofoam and PET products to degrade.
Georgia Tech said these additives, “simple organic substances that built on the known structures of materials that induce polymer biodegradation,” didn’t affect plastic performance, introduce heavy metals or toxic chemicals to the environment, or stop recycling.
Detter Hoskin said that research to date suggested that treated plastics could biodegrade completely within five to 10 years depending on landfill conditions.
She said: “However, legislators, regulatory agencies and consumers need more assurance that these containers will perform as expected in actual landfills.”
Andrus said pressure group Californians Against Waste had created particular problems for ENSO, but pressed as to whether ENSO had considered taking action to correct what he said were incorrect statement, said the company would just “let science speak for itself”.
There was also a need to correct the misunderstanding that ENSO’s product was either PLA (corn-based) or oxo-biodegradable, he added.
Ultimately, ENSO was committed to a stance whereby all packaging innovations that “move the market forward” had a place, he said.