Tesco began rolling out its new degradable plastic carrier bags to all its stores earlier this month (see letsrecycle.com story). The bags contain an additive, TDPA, created by EPI Environmental products which causes the plastic to become brittle and begin to break down after 18 months.
The plastic bags have not been certified by the American ASTM or European EN standards for compostable products.
Diana Meskauskas, environmental officer for EPI, said while the bags did not meet the standards as such, they did meet three of the four criteria within them.
”EPI currently meets 3 of the 4 requirements of compostability as outlined by ASTM and the European Standard“
– EPI Environmental Products
She explained: “As it relates to certification as being compostable, plastics containing EPI’s TDPA additives meet the critical requirements as outlined by ASTM and EN, the United States and European Standards bodies, except to the rate of carbon to carbon dioxide conversion… EPI currently meets 3 of the 4 requirements of compostability as outlined by ASTM D6400-99 and the European Standard EN 13432.”
Both standards state that in order for a product to be compostable the following criteria need to be met:
- 1. Disintegration, the ability to fragment into non-distinguishable pieces after screening and safely support bio-assimilation and microbial growth;
- 2. Inherent Biodegradation, conversion of carbon to carbon dioxide to the level of 60%, over a period of 180 days (ASTM D6400-99) and 90% in 180 days for the European standard (EN 13432);
- 3. Safety, that there is no evidence of any eco-toxicity in finished compost and soils can support plant growth; and
- 4. Toxicity, that heavy metal concentrations are less than 50% recommended values.
Ms Meskauskas added: “TDPA additives meet all criteria except number 2, the rapid carbon to carbon dioxide conversion rates. Plastics made with TDPA additives degrade and ultimately biodegrade slower than required by ASTM D6400-99 and EN 13432. This does not mean that they will not biodegrade, they just convert the carbon to carbon dioxide in a slightly longer time frame. Many naturally occurring materials, all biodegradable, do not rapidly convert in the time frames established by the ASTM D6400 and EN13432.”
Din Certco
In December 2003, the Composting Association launched the German Din Certco standard for compostability which is based on the EN certification (see letsrecycle.com story).
Jane Gilbert, chief executive of the composting association, said: “We are running a compliance scheme so that when customers, local authorities and retailers buy compostable bags they know they are complying with European standards.”
Norbett Muller of the German standard company Din Certco told letsrecycle.com that Tesco has not applied for the company's standard for compostability and biodegradability for the new degradable bags. He said: “There are many many questions behind these products and we would want a statement from Tesco that these products are biodegradable.”
“They are allowed to call it biodegradable but we think that without certified proof or tests the biodegradability is not in fulfilment of the requirements,” Mr Muller added, “This must be proven by an independent company or independent body like Din Certco.”
Update February 5, 2004:
Further to this article, Ms Meskauskas has commented: “I would like to point out that EPI has not made any claims that TDPA incorporated carrier bags (including Tesco's 100% degradable bags) are compostable and have pointed out that we do not meet the European “compostable” standard for certification.”
She added: “EPI has a number of tests and test results that support degradability and biodegradability, for example the Raninger Report (1998), as well as the University of Pisa (Italy) and the Centre National d'E;valuation de Photoprotection (CNEP) of the Universite de Clermont II (2001) (France) which reported, based on testing and data, that TDPA incorporated plastics biodegrade.”
As there are currently no standards for oxo-biodegradable plastics, EPI's TDPA has to be tested against existing standards for biodegradation. EPI is now working with ASTM to develop oxo-biodegradable plastics standards and intends to work on similar standards for Europe.
Ms Meskauskas noted: “Though it does not meet the current European Standard for Compostability, EPI's TDPA technology does work in well maintained and managed commercial composting operations and will oxidize and fragment in 30-60 days and ultimately biodegrade, leaving no harmful residues or toxins to human or the environment. Bags suitable for commercial composting are not the carrier bags used by Tesco in their 100% degradable program, rather they are bags specifically designed with a different formulation and different addition rate.”
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