The UK government is set to introduce a 5p charge for plastic bags in supermarkets after the 2015 election, following the lead of Wales and Northern Ireland (where a charge is already in place) and Scotland, where charging starts this October (Plastic bag charge to be introduced in England). The Northern Ireland Environment minister claimed that plastic bag use had been reduced by 80% since free bags were withdrawn.
In England, this charge will only apply to supermarkets and large shops, leading some to question its usefulness. The House of Commons Environmental Audit Committee, for example, is not impressed (Plastic bag charge a ‘complete mess’). Their concern is that the system will be overly complicated, as not only are small convenience stores exempted, but no charge will be paid on paper or biodegradable bags.
Encouraging waste of any kind should, of course, always be avoided. Campaigners for reducing the use of plastic bags argue that they are a threat to marine life and the countryside, and anyone who sees them caught in hedges or lying at the side of roads would agree they are unsightly. But the counter-argument is that plastic bags are simply the wrong target, chosen because of their visibility rather than their degree of environmental impact.
It is reported that over eight billion disposable carrier bags are used in England every year: that’s something like 120 per head. With a typical bag weighing about eight grams, that’s 64,000 tonnes of plastic, or just under a kilo per head. In the overall scheme of things, that is pretty small compared to the packaging of the goods carried home in the bags.
None of this primary packaging will be reused, though increasingly it will be put out for recycling. This is better established for plastic bottles, but according to WRAP, 17% of local authorities were offering collection schemes for plastic bags and other plastic films in 2013 (Fast facts for plastics). ‘Single trip’ carrier bags are often reused at least once more if not recycled. Many families use them as waste bin liners, which saves on purchase of other, more specialised single-use bags.
In areas where plastic bags are not collected, consumers have the option of returning them to supermarkets. If not recycled when thrown away, bags may be incinerated and used to generate heat or power. The final option is landfill, although this is being discouraged via taxation and the sorting technology available to local authorities should allow most burnable waste to be recovered from general rubbish.
If plastic bags are not used, then we need to look at what would replace them: in general either thicker plastic ‘bags for life’, paper or reusable cotton bags. The Environmental Audit Committee report gathered evidence from many sources and has a lot of useful, up to date information. Some of this is rather counter-intuitive.
For example, “The evidence from life-cycle analysis suggests that a paper bag needs to be reused at least three times to make its emissions impact lower than that of a typical single-use plastic carrier bag” (study from the Environment Agency). Paper bags also use more material and are less robust; it is unlikely that large numbers are reused. Admittedly, they can be composted or burnt, but their impact on carbon dioxide emissions is surprisingly high.
In comparison, what are characterised as ‘thin’ bags for life, made from LDPE, would need to be used only four times to have a lower environmental impact and thicker bags (non-woven PP) eleven times. For families who use such bags – often kept in car boots ready for shopping trips – reuse will often be many times that.
As for use of material bags, the report says “A reusable cotton bag, for example, would need to be reused over 130 times (equivalent to daily use for over four months) to have the same impact as a thin plastic bag used once. This would increase to 393 times if the plastic bag were used three times.” At the end of its life, a cotton bag would need to be incinerated or go to landfill; the fibre cannot sensibly be reused.
With at best a very modest reduction in carbon dioxide emissions, one of the main justifications for the bag tax is to reduce littering. This may happen, but it is difficult to find hard evidence one way or the other. After all, there are many other types of litter, and individuals who are happy to dump drink cans, cigarette packets and fast-food containers on the ground would probably have little compunction about doing the same with a carrier bag, even if they had been charged 5p for the privilege. If we want to reduce the unpleasant and antisocial habit of littering, charging for bags is just going to scratch at the surface.
There is, however, another factor, which is the effect on wildlife, and marine creatures in particular. There are many reports of seabirds, whales and turtles being found dead with significant numbers of plastic bags in their stomachs. The animals consume them – sea turtles are said to mistake plastic bags for squid and other species can eat them with other food – and, of course, they are not broken down in their digestive systems. Even degraded plastic particles can be eaten, and these may have adsorbed toxins.
The extent of this is unknown, but it is part of a wider picture of waste being disposed of in the sea. In the same way as on land, littering is something which must be actively discouraged, but plastic bags are only a small part of the overall problem. This leads to the conclusion that a major motivation for the government is to be seen to be taking action on an environmental issue which is both high profile and with little economic consequence.
Martin Livermore
The Scientific Alliance
St John’s Innovation Centre
Cowley Road
Cambridge CB4 OWS
______________________________________________