Battlelines drawn in BSI over degradable polymers

Compost producers fear that attempts by manufacturers of degradable oil-based plastics to widen the accepted definition of "biodegradable" to include their materials could lead to the production of sub-standard composts - something strongly denied by degradable plastics producers.

The rapidly growing market for degradable plastics can be divided into two main types of materials. A number of companies, including multinationals such as Cargill Dow, produce polymers from crops such as maize or potatoes that biodegrade through hydrolysis. Such materials do not appear to hinder composting and have support from the Government and the National Non-Food Crops Centre as a way to help farming diversify (ENDS Report 352, p 53 ).

In addition, companies such as Symphony Environmental and EPI produce oil-based plastics which degrade through oxidation. Supermarkets including Tesco and the Co-op use these plastics for their carrier bags - even though most end up in landfill sites where they degrade to produce methane, a powerful greenhouse gas. Some composting firms have also found that such materials do not always disintegrate under compost-site conditions (ENDS Report 348, p 27 ).

Work to revise the European standard for compostable packaging, BS EN 13432, has increased tensions between the two camps. Degradable polymers such as Symphony's do not meet the standard and are therefore ineligible for the Composting Association's "compostable" logo for packaging materials.

To overcome this, the industry is involved in the development of a British standard for the compostability of oxo-degradable plastics which it hopes will lead to the European standard being amended to include oxo-degradation as a form of biodegradation.

A new standard guide formally recognising the existence of oxo-biodegradable plastics was recently approved by the US standards body, American Standard Testing Methods (ASTM).

Elements of the composting sector have claimed that the BSI sub-committee drawing up the British standard is loaded in favour of the degradable polymer producers. As well as representatives of Symphony and two other degradable polymer producers, it includes a representative of Symphony customer the Co-op and consultants - including the sub-committee chairman Professor Gerald Scott - who have carried out research for Symphony.

Professor Scott, who told ENDS he had personally invented the oxo-degradation process in the 1970s, refuted all suggestions of bias. Other members, he said, included representatives of the Environment Agency, the NNFCC and Composting Association chief executive Jane Gilbert.

BSI committees and working groups work on the principle of consensus at each stage of the process. But in practice, there is often pressure on committee members to fall into line.

Ms Gilbert, whose members include Symphony, said that while the association was happy to provide comments to the sub-committee, "this does not imply endorsement of any of the outputs of the group, nor membership of the group per se."

The current draft of the standard would, she said, be unacceptable to compost producers. "Composting Association members have worked hard over recent years to build markets for their composts, and it is imperative that these are not undermined."

Similarly, NNFCC deputy director Maggie Smallwood said her organisation was "very keen to ensure that biodegradable plastics can be dealt with by current composting techniques."

Professor Scott said that, provided enough air can reach the oxo-degradable plastic in a composting plant and the material is screened to remove contaminants, oxo-degradable plastics should not cause any problems.

However, the Environment Agency, which is conducting life-cycle assessments comparing the environmental performance of oil- and starch-based polymers, is said to be concerned that non-degraded plastic could end up in the environment through the landspreading of compost.

The Environment Department (DEFRA), meanwhile, has told the sub-committee that "the principle of allowing a non-renewable resource to degrade goes against Government policy on reuse and recycling when there are fully biodegradable products available made from renewable resources."

But describing this as a "naïve" view, Professor Scott claimed that more fossil fuels are used to make polymers from natural resources than from oil.

Professor Scott, who described himself as "BSI's specialist on degradable materials", said that he also sits on a European standards committee looking at composting after he was "asked to" by EPI, the degradable polymer producer that used to licence its technology to Symphony.