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Proposed Plastic Bag Levy - Extended Impact Assessment: Volume 1: Main Report


2 Introduction

The estimates for the number of lightweight plastic carrier bags issued in the UK vary from 8 billion [Defra 2003] to 10 billion [ WRAP 2005]. From these, a range of 690-860 million has been estimated for use in Scotland based on population statistics. The calculations and assumptions behind this range are given in Section 4.3. The estimated cost of these bags to UK retailers also varies. Some sources suggest the cost to UK retailers is around £1 billion per year [ BBC, WRAP 2004b], whereas the Carrier Bag Consortium ( CBC) suggests that, based on the unit price of bags, the cost is closer to £64-80 million.

2.1 The Different Types of Carrier Bags

Most outlets currently provide free lightweight bags 3 made from conventional polyethene (polyethylene) plastic or bags made from degradable plastic (some outlets do make a charge 4). Most major supermarket retailers also offer heavyweight reusable bags known as 'bags for life', for which they charge a small sum. Some shops also provide paper bags free of charge. The main types of carrier bags are described below; Table 2.1 summarises their key features.

Disposable High-Density Polyethene ( HDPE) Bags

These plastic bags offer a thin, lightweight, high strength, waterproof and reliable means of transporting shopping. Research and development by the industry has reduced the average weight of such a bag by 60% compared with 20 years ago, while retaining the same strength and durability. Such bags are currently found in supermarkets and other food retail outlets.

Disposable Low-Density Polyethene ( LDPE) Bags

These bags are currently given away free by many UK retailers ( e.g. clothing shops). Like their HDPE counterparts, they are made from a by-product of oil refining.

Reusable Low-Density Polyethene ( LDPE) Bags,

These are heavier gauge plastic carrier bags, often called 'bags for life'. Retailers charge for these (typically around 10p). The intention is that the customer uses them repeatedly and then returns them to the store for recycling when they are worn out, receiving a free replacement. Such bags are offered in many UK supermarkets.

Paper Bags

The paper bags issued by shops range from very simple ones for small items ( e.g. from newsagents and greengrocers) to larger ones ( e.g. issued by fashion and shoe retailers). Some paper bags have plastic handles or plastic coatings. Under the terms of the Irish definition of plastic carrier bags ( i.e. a bag with a plastic content), it is assumed that paper bags with a plastic content would be subject to the levy.

It is a misconception that paper bags are environmentally friendly because they are biodegradable. The increased volume of waste and the impact of their manufacture and transportation all need to be taken into account.

Polypropylene Bags

Polypropylene 5 has many uses for producing rigid and flexible containers, as well as furniture, and is also derived from oil resources. Non-woven polypropylene bags are available at shops such as Marks and Spencers in the UK, where they retail at more than £1. They are strong and durable and, like 'bags for life', are intended to be used many times.

Woven polypropylene bags are available at J Sainsbury in the UK as well as in the Republic of Ireland at Tesco and Dunnes stores. Woven bags are produced by stretching the polypropylene in production to form "fibres", the result is a stronger bag.

Degradable Bags

Bags that can be broken down by chemical or biological processes are described as degradable. Intuitively, degradable bags are expected to be environmentally friendly and a number of retailers are actively pursuing this option. Thus, there is often some surprise when reports suggest that degradable bags are not such an 'environmentally friendly' option. Waste management protocols emphasise the need to prevent, reduce, reuse, recycle and then recover energy. Encouraging disposal via degradation runs counter to this approach.

It can also be difficult to agree whether a particular type of bag is degradable or not. This could become significant if biodegradable bags were to be exempt from the levy.

Types of degradable bags

There are two main kinds of degradable bags 6.

  • Biodegradable bags are made from natural starch sources such as maize and synthetic polyesters that degrade through the enzymatic action of micro-organisms (bacteria, fungi and algae), essentially rotting down like vegetable matter. However, starch-based biodegradable carrier bags are not available in significant numbers in the UK. They would only be covered by a potential levy on plastic carrier bags if they contained some plastic (some do for bag-strengthening reasons).
  • Bioerodable bags are made from synthetic plastics (oil-based) with trace degradation initiators ( HDPE with an approximately 3% content of heavy metals such as manganese and iron 7) and, as such, would be covered by a plastic bags levy. They bioerode primarily by oxidation and erosion of the plastic through the action of light and heat until very small particles of plastic remain (these often degrade biologically). It is reported that, in an anaerobic environment, the degradation process is halted for some types of bioerodable bags [ RMIT, Symphony Plastic Technologies].

Concerns Regarding Bioerodable Bags

  • Recycling. Conventional polyethene plastic bags ( HDPE and LDPE) can be recycled into new products such as other bags and solid items such as 'plastic' wood (known as plaswood). It will be difficult to keep the different kinds of bag apart ( HDPE and LDPE bags for recycling and bioerodable bags for composting), especially if both are available in the same community. Inevitably, bioerodable bags will get into this plastic bag waste stream and thus contaminate the recyclate. If the resulting recycled item contains a certain percentage derived from bioerodable bags, it will have inherently lower functional properties ( i.e. it will start to degrade when in contact with water, ultraviolet light, etc.). This could have serious implications if the recycled plastic is used for pipes for water, gas supply or as fencing posts or seats [ RMIT]. Some types of bioerodable bags 8 are reported not to damage the overall value of the reclaimed material as the degradant initiator is destroyed during reprocessing.
  • Shelf-life and storage. Bioerodable bags may start to decompose early if exposed to high temperatures, light or moisture. This compromises their carrying ability, though vacuum packaging is reported to prevent this [Symphony Plastic Technologies].
  • A solution to littering problems. This claim is felt to send the wrong message to the consumer, i.e. it is acceptable to discard these bags because they will eventually rot down. The argument is that consumers should be informed of the need to reuse bags to reduce litter and resource consumption [ RMIT]. In addition, the Marine Conservation Society ( MCS) reports that any littered bioerodable bags based on HDPE will still cause problems to wildlife as they will break down into smaller pieces that can be ingested [ MCS 2005]. This is questioned by Symphony Plastic Technologies, which suggests that degradation to carbon dioxide, water and humus is likely and that, should an animal ingest these smaller pieces, the degradation process will actually continue in its gut.
  • Provision of appropriate conditions for planned benign degradation. Bioerodable bags are designed to decompose through the action of sunlight, water, stress and, ultimately, the enzymatic action of microbes in an aerobic environment. Where degradable bags are simply disposed of alongside other 'household waste' and then landfilled (like most household waste in Scotland [ SEPA]), then the necessary conditions to allow degradation may well be absent and thus the environmental 'benefits' lost.

Certification and Labelling

Manufacturers of degradable polymers have signed a voluntary agreement with the European Commission to use environmentally friendly polymers in packaging that "will effectively guarantee a biodegradability standard for products such as plastic bags, cups and plant pots, enabling them to be turned into compost and soil improvers." The agreement includes a certification and labelling scheme to help consumers and manufacturers identify products made from degradable polymers [ EU Commission].

Key Features of Carrier Bags

Table 2.1 summarises some of the key features of the various types of carrier bags available, including their costs and relative sizes compared with conventional lightweight plastic carrier bags.

Table 2.1 Key features of carrier bags

Bag type


Average cost to the retailer per thousand bags *

Average weight per thousand bags (kg) *

Relative bag storage volume **


Lightweight plastic carrier

Light, strong, durable, effective when wet




Yes - but not all stores have facilities

'Bag for life'

Light, strong, durable, effective when wet




Yes - system of replacement actively encouraged

Fully degradable plastic bag

Light, strong, durable, effective when wet

£6 to £8



Degradable under the right conditions. Problematic if contaminate conventional plastic recycling.

Paper, without handles §





Yes - kerbside collections available

Paper, with handles §

More appealing to customers e.g. for shoes and clothes




Yes - kerbside collections available but can be more problematic due to mixed materials

Non-woven polypropylene

Durable, strong, effective when wet




Not at present

Woven polypropylene

Durable, strong, effective when wet




Not at present

* Data provided by CBC and Symphony Plastic Technologies plc. Based on average price of an average bag.
**The relative volume of bags (to a conventional lightweight bag) is important for transportation and storage units required compared with plastic carrier bags.
§ The average weight of all paper bags available is 99g (arithmetic mean of 51, 81 and 166g). The values of 51g and 99g are used in the LCA in Section 4 for various analysis sensitivities.

2.2 Summary of the Irish Experience

A key motivator for the introduction of a levy on plastic bags in Scotland is the experience from the Republic of Ireland, where a levy known as the PlasTax was introduced in 2002. We consulted the Department of Environment, Heritage and Local Government in the Republic of Ireland for its views on the introduction and operation of the PlasTax. The Department said:

  • The PlasTax was primarily an anti-litter measure with the secondary aims of increasing public awareness and changing behaviour. Introduction of the levy coincided with introduction of Ireland's Waste Strategy.
  • No documented evidence is available showing a reduction in visible litter in the Republic of Ireland because of the levy. The Department has commented that "littering of plastic carrier bags is no longer a problem".
  • Approximately €1 million are raised each month from the levy.
  • The decrease in bag usage was initially 90% and is now 95%.
  • The main cost to retailers was updating their software so that till receipts would itemise the sale of plastic carrier bags.
  • Theft was reported to increase at the outset but, when the Department investigated these claims, they were unable to substantiate them.
  • Some increased control measures were introduced to stop trolleys being taken away from stores.
  • Although use of paper bags has increased, it is not felt that their exclusion from PlasTax has been to the detriment of the scheme. Paper bags are reported as being used mainly by fashion and shoe shops. The grocery sector has switched largely to reusable bags.
  • The advertising campaign, which was high profile and intensive, was considered a successful element in smoothing introduction of the levy.
  • There are approximately 30,000 accountable persons registered in the Republic of Ireland. An accountable person is responsible for submitting the required information to the Revenue Commissioners.
  • Compliance levels are reported to be very good. There is a facility for 'estimating levy liability' if retailers fail to submit returns or if the return is considered too low.
  • There have not been any prosecutions. Any retailer not complying with the law has been visited, their non-compliance verified and a warning issued.
  • Funds have been used to support waste recycling infrastructure, ongoing running costs and the introduction of dedicated staff to enforce waste legislation (with a particular focus on illegal waste dumping).
  • An independent review of the scheme will be undertaken during 2005, three years after its introduction.
  • A voluntary code was considered but the advice received suggested that this would be less effective.