RESPONSE TO IBAW “POSITION” ON DEGRADABLE PE SHOPPING BAGS

The first point to note is that IBAW claims to represent the manufacturers of biodegradable polymers. In fact they represent only the manufacturers of hydro-biodegradable polymers. These have their uses, but they are quite different from oxo-biodegradable polymers with which they are in competition. Their published “position” is an attempt to disparage oxo-biodegradable polymers, not in the interests of consumers but for their own commercial purposes. Their “position” is misleading for the following reasons:

EN 13432

This European standard applies only to composting of plastic packaging, and was written before oxo-biodegradable plastics became popular. It is not appropriate for testing oxo-biodegradable plastics because it is based on measuring the emission of carbon dioxide during degradation. Perversely therefore, hydro-biodegradable plastic, because it emits CO2 (a greenhouse gas) at a high rate, is compliant with EN 13432.

Another perversity of EN 13432 is that it requires almost complete mineralisation of the carbon in the plastic, thus depriving the resulting compost of carbon, which is needed for plant growth, and wasting it by emission to atmosphere as CO2. Oxo-biodegradable plastic when composted will by contrast retain most of the carbon, and release it slowly to the plants. Oxo-biodegradable plastic is particularly suitable for in-vessel composting at the high temperatures required by the Animal By-products Regulations.

Conversion of organic materials to CO2 during the composting process is not “recovery” as required1 by the European Directive on Packaging and Packaging Waste (94/62/EC as amended), and should never have been part of a standard for composting. Nature’s lignocellulosic wastes do not behave in this way and if they did, the products would have little value as soil improvers and fertilisers.

The Directive does NOT require that when a packaging product is marketed as “degradable” conformity with the Directive must be assessed by reference to EN13432. In the first place EN 13432 applies only to composting.2 Secondly the Directive3 provides that conformity with the essential requirements may be presumed if EN 13432 is complied with, but it does not exclude proof of conformity by other evidence. Such evidence could, for example, be a report from a reputable testing agency.

There is as yet no European standard designed for testing oxo-biodegradable plastic, and the standards organisations (which are not free from commercial pressure from the hydro-degradable industry) have so far failed to provide one. Draft British standard 8472 is intended to rectify this deficiency, but is being opposed by the hydro-biodegradable industry to serve their own commercial interests, and contrary to the interests of consumers.

CERTIFICATION AND LABELLING

As mentioned above, there is no requirement for plastics claimed to be “degradable” or “biodegradable” to be certified or labelled as compliant with EN 13432, as the standard applies only to compostability. Even in relation to compostability there is, as mentioned above, no requirement to certify compliance with EN 13432.

PRODUCT SAFETY AND ECOTOXICITY

Oxo-biodegradable plastics have been tested by reputable testing agencies and have been found not to be eco-toxic.4

Metal compounds listed in European Directive 67/548/EC are not banned. The Directive simply controls their marketing and use, and they are marketed and used accordingly. In any event, cobalt is used in oxo-biodegradable plastics in the form of stearate, which is not listed in the Directive. Even this is now being phased out.

It should be understood that trace-elements are necessary for healthy plant and human growth, and that cobalt and manganese are required dietary supplements. An Expert Group on Vitamins and Minerals of the UK Food Standards Agency5 carried out a risk assessment on trace elements, and found that high concentrations of cobalt are contained in fish, nuts, green leafy vegetables and fresh cereals. The only toxicity data for cobalt reported in the literature was in 1960, when heavy beer drinkers suffered as a result of the use by the brewing industry of cobalt chloride.

It is ridiculous to point out that “cobalt has been found in concentrations higher than 4,000 mg/kg in oxo-biodegradable additives.” Nobody is going to eat the additive, and it is not sold to consumers. Manufacturers are well accustomed to handling materials in an appropriate manner, in accordance with legislation and with due regard to the safety of their workforce. The oxo-biodegradable plastic industry is no exception.

RISK OF PERSISTENCY AND BIO-ACCUMULATION

It is not of course acceptable to apply conventional plastics to the soil even if they are fragmented, since physical shredding alone does not transform the plastic into a biodegradable product.

However, oxo-biodegradable plastics are designed to fragment by a process which includes both photo-oxidation and thermo-oxidation, so it will work even in the absence of light. The properties of peroxidised and embrittled polyolefins are quite different from those of the original plastic. The transformed plastic is not “resistant to biodegradation” and behaves in the same way as nature’s wastes. It is bio-assimilated by the same bacteria and fungi, and they transform the plastic degradation products to cell biomass, like lignocellulosic materials.

The resulting compost, which contains particulate and partially biodegraded plastics, is premium quality material and passes all the usual ecotoxicity tests. These include seed germination, plant growth and organism survival (daphnia, earthworms) tests carried out in accordance with DIN V 54900-3, ON S 2200 and ON S 2300 national standards.6

Oxo-biodegradable plastics have been used as protective films in agriculture for the past 30 years in many countries (including USA, China, Japan and the EU). They are applied to the land in the same way as straw to retain moisture and to increase root temperatures. Considerable attention has been paid to the effects of oxo-biodegraded polyolefins in the soil environment. These materials have been used annually for up to 15 years in the same fields without any adverse effects on soil fertility.

Like lignocellulose (and unlike the hydro-biodegradable plastics which mineralise completely during composting), oxo-biodegradable plastics are sequestered by the soil and enhance the “land carbon sink”

LITTERING

Oxo-biodegradable plastics do indeed decompose if they become litter in the natural environment, and this is one of their principal benefits.

Discarded conventional plastics remain in the environment for many decades, and are often impossible or too expensive to collect, so recycling, landfill, composting, and incineration are not options for dealing with them. Oxo-biodegradable plastic on the other hand will harmlessly biodegrade and disappear in a predetermined time, leaving no harmful residues.

Oxo-biodegradable plastic bags have been dispensed by supermarkets in England for more than two years, but there is no evidence that people dispose more carelessly of degradable bags, and they have not been encouraged to do so. But suppose that 10% more were discarded. If 1,000 conventional and 1,100 oxo-biodegradable bags were uncollected, 1,000 conventional bags would remain in the rivers, streets and fields for decades, but none of the oxo-biodegradable bags would be left at the end of the short life programmed into them at manufacture.

Yes, people should be educated, but in the real world there will always be people who will deliberately or carelessly discard their plastic waste. What will happen to all the plastic waste that will not be recycled or incinerated, and instead will litter the countryside - would it not be better if the discarded plastic were all oxo-biodegradable?

It is nonsense to suggest that oxo-biodegradable bags will “endanger organic recovery schemes.” Indeed they will assist such schemes, because the organic waste can be put into oxo-biodegradable bags where it will not smell or attract flies. These can then be put into a composting vessel without the need to open the bags and dispose of contaminated plastic.

PLASTIC RECYCLING SCHEMES

Oxo-biodegradable products do NOT endanger recycling processes of plastics.

Oxo-biodegradable plastics can be recycled, and will not cause problems in a recycling scheme. During the cleansing, separation and re-extrusion process degradation is arrested, and the recycled plastic reverts to the properties of conventional plastic.

Oxo-biodegradable plastics can themselves be made from recyclate.

Hydro-biodegradable plastic cannot be made from recyclate. Nor can it be recycled unless extracted from the post-consumer waste stream and treated separately, at prohibitive cost.

WHAT IBAW DO NOT TELL YOU ABOUT THEIR HYDRO-BIODEGRADABLE PLASTICS

First, they are many times more expensive. They are not therefore competitive in the marketplace in the absence of subsidies or artificial legislative constraints.

Next, hydro-biodegradable or “starch-based” plastics made from agricultural produce are not a preferred alternative. They emit both carbon dioxide and methane (which are both greenhouse gases) as they degrade. Methane also causes explosions in landfill schemes.

Nor are they really “renewable” because the process of making them from crops is itself a significant user of hydrocarbon energy and a producer therefore of even more greenhouse gases. Hydrocarbons are burned by the autoclaves used to ferment and polymerise material synthesised from biochemically produced intermediates (e.g. polylactic acid from starch etc); and by the agricultural machinery and road vehicles employed; also by the manufacture, transport, and application of fertilisers and pesticides.

Degradable polymers manufactured from crops have greater impacts upon eutrophication due to the application of fertilisers to land. They also have higher impacts upon greenhouse due to N2O emissions from fertilizing crops.

Hydro-biodegradable plastic is sometimes described as made from “non-food” crops, but it is in fact usually made from food crops such as maize. Also, it often contains a proportion of synthetic plastic derived from oil.

As compared with hydro-biodegradable, the oxo-biodegradable plastics have the following advantages in addition to those already mentioned:

1.They will degrade in any normal outdoor or indoor environment, even in the absence of light and water. However, almost all of the hydro-biodegradable plastics need to be in a highly microbial environment such as a compost heap before they will degrade.

2.Oxo-biodegradable plastic can be programmed at manufacture to degrade within a timescale to suit the user’s requirements. The rate of degradation of hydro-biodegradable plastics cannot be controlled.

3.Oxo-biodegradable plastics are stronger and more versatile.

4.They are thinner, and use less space to store and transport, and less material to produce

5.They can be transparent, so that the food or other contents within can be clearly seen.

6.Bags made from them do not leak

7.Less energy is required to produce and transport them.

8.No genetically-modified ingredients

9.Safe for direct food contact

10.Ideal for frozen food because they can be kept for long periods in sub-zero temperatures and will not start to degrade rapidly until the frozen food has been used and the wrapper has become waste.

11.They can be used in high-speed machinery (such as for bread packaging) but the performance of hydro-biodegradable plastics in these machines is not acceptable.

12.They can be incinerated with much higher energy-recovery than hydro-biodegradable plastic

13.They can be made with the same workforce and machinery as conventional plastic products, but hydro-biodegradable products are made by a quite different process.

14.It seems wrong to divert land and agricultural resources away from food production when there is so much hunger in the world, and to use fertilisers and pesticides unnecessarily

Oxo-biodegradable is the plastic of the futur