Plastic fantastic! Carrier bags 'not eco-villains after all'

Unpublished UK Environment Agency research shows polythene may be less harmful than cotton or paper
Martin Hickman, The Independent 20 Feb 11;

Unpublished government research suggests the plastic carrier bag may not be an eco-villain after all, but – whisper it – an unsung hero. Hated by environmentalists and shunned by shoppers, the disposable plastic bag is piling up in a shame-filled corner of retail history. But a draft report by the Environment Agency, obtained by The Independent on Sunday, has found that ordinary high-density polythene (HDPE) bags are actually greener than supposedly low-impact choices.

HDPE bags are, for each use, almost 200 times less damaging to the climate than cotton hold-alls favoured by environmentalists, and are responsible for less than one-third of the CO2 emissions of paper bags given out by retailers such as Primark.

The findings suggest that, in order to cancel out the tiny impact of each lightweight plastic bag, consumers would have to use the same cotton bag every working day for a year, or use paper bags at least three times rather than sticking them in the bin or recycling. Most paper bags are used only once, and one study assumed cotton bags were used only 51 times before being discarded, making them – according to this new report – worse than single-use plastic bags.

However, despite being commissioned in 2005 and scheduled for publication in 2007, the research has not been released to the public. Officially, the Environment Agency says the report, Life Cycle Assessment of Supermarket Carrier Bags, by Dr Chris Edwards and Jonna Meyhoff Fry, is still being peer-reviewed. However, it was submitted to the peer-review process "more than a year ago". The Environment Agency does not have a date for its publication, except to say that it will be soon.

The report set out to find out which of seven types of bags have the lowest environmental impact by assessing pollution caused by extraction of raw materials, production, transportation and disposal. It found that an HDPE plastic bag would have a baseline global warming potential of 1.57kg CO2 equivalent, falling to 1.4kg if reused once, the same as a paper bag used four times (1.38kg CO2e). A cotton bag would have to be reused 171 times to emit a similar level, 1.57kg CO2e.

The researchers concluded: "The HDPE bag had the lowest environmental impacts of the single-use options in nine of the 10 impact categories. The bag performed well because it was the lightest single-use bag considered."

The 96-page report comes amid an ongoing controversy over plastic bags and plans in Wales to introduce a 5p plastic bag tax in October.

Six billion plastic bags are used in the UK annually, and there is no doubt that they cause environmental problems and that reusing them reduces the harm. However, the new report suggests that if shoppers switch to alternatives, they have to use those time and time again to be greener.

Barry Turner, chief executive of the Packaging and Films Association, which represents plastic bag manufacturers, suggested the report had been "suppressed". "They [the Environment Agency] have kept it fairly quiet and tried to suppress things," he said. "It was a report that could have been done relatively quickly, but it has gone on for years. If these are the conclusions they have arrived at, it wouldn't really surprise me. It was buried because it didn't give the right answers. It doesn't support the political thrust at the moment."

The Environment Agency denied the report had been suppressed. "The initial draft went to the review panel just over a year ago but they have not been constantly engaged in the review," a spokesman said. "Also we amended the report after the comments from the first review and then the revised report was resubmitted to them last summer but, because it was a panel and because of their other commitments, it has taken them some time to complete." Asked whether the draft findings had been seriously challenged, he said the reviewers had "questioned some aspects of the original draft, although much was about emphasis and balance".