Further research is needed into biodegradability standards before biodegradable bags can be made exempt from the English carrier bag charge, according to a Department for Environment, Food & Rural Affairs (Defra) review.

Under the Single Use Carrier Bags Charges (England) Order 2015, retailers with 250 or more employees are required to charge at least five pence for each single-use carrier bag, unless they are being used for carrying unpackaged food or sharp objects.

Paper bags were also exempted from the charge and as part of the order, and Defra was to complete a review of industry standards for biodegradability to determine whether biodegradable carrier bags warranted an exemption from the charge.

The report was due before the charge was introduced on 5 October this year, and has today (17 December) been released after a three-month delay.

However, the review has returned inconclusive results, stating: ‘There are a number of standards for plastic bag biodegradability. We will need to conduct further work before any of these could be used to exempt certain types of carrier bags on grounds of biodegradability.’

It states that the impact of the charge will be assessed after retailers have reported bag-use figures and proceeds from the charge in May 2016. Defra will ‘continue to consider the technical specification for a genuinely biodegradable bag, and will at that point further report on how an exemption for such a biodegradable bag can be implemented’.

Review findings

The review concluded that a number of standards exist for plastic bag biodegradability, all of which degrade in different ways and are likely to have different impact when incorporated into recycled plastic reprocessing streams.

These include plant-based biodegradable bags, which are made from plant-based material like starch that break down in composting environments, and oxo-biodegradable bags, made with normal plastics such as polyethylene but with an additive to catalyse the degradation process in the presence of oxygen.

The review was carried out to ensure that any bag exempted from the charge would biodegrade in a wide range of environments, including soil, rivers and the sea.

A technical advisory group of academics concluded that ‘it is not currently possible to assemble a standard specification that would ensure that plastic bags claiming to be biodegradable would biodegrade in all environments, in particular in the open environment’.

Meanwhile, a review of existing standards for the biodegradability of plastic carrier bags in managed organic environments found that no existing test standards on the biodegradability of filmic plastics in aerobic compost, anaerobic digestion or anaerobic landfill could be used to support an exemption on the grounds of biodegradability in the open environment.

Over complicated charge

The English carrier bag charge has been criticised throughout its development for the number of exemptions included in it. Similar schemes in the other UK countries, all implemented prior to the English charge, do not exclude paper or biodegradable bags and are enforced in all shops regardless of number of employees.

Speaking after the release of the Environmental Audit Committee’s (EAC) 2014 report into plastic bags, its former Chair, then-MP Joan Walley, called plans for the English charge ‘unnecessarily complicated’ and based ‘more on wishful thinking than hard evidence’.

When the charge was introduced in October, a number of organisations representing small retailers voiced their disappointment that small businesses were excluded from the charge, stating that the exemptions create confusion for shoppers and retailers alike, and require shops to convey ‘complex messages’ to consumers.

Investment in biodegradablity

Commenting on the report, David Newman, Managing Director of the Bio-based and Biodegradable Industries Association (BBIA), said: "BBIA welcomes the report from Defra while believing that the mandate was, in the first place, not realistic. We knew full well that no plastic material exists that is able to biodegrade everywhere. Indeed such a material could be defined as a license to litter. Nevertheless, the report recognises that a standard exists to define biodegradation in a confined space and time and that it actually works quite well, the EN13432.

"What the report fails to recognise is the investment the biopolymer industry is making in producing materials that could biodegrade everywhere – this investment is on the back of a decade of producing materials that use less resources, produce less emissions and help reduce waste. I am certain that within a few years a material will be ready that can biodegrade in every environment and the biopolymer industry is leading the research in this important sector."

The full Defra 'Review of standards for biodegradable plastic carrier bags' can be found at Defra's website.