Plastic wastes that litter cities, parks, beaches and countryside look depressingly the same everywhere on earth. They have come to symbolise the mass throwaway culture: cheap, trashy, transient yet stubbornly non-degradable and inassimilable. These by-products of the oil industry are icons of the industrial economy built on the over-exploitation of oil and other fossil fuels that’s turning the planet literally into a terminal wasteland. Dealing with plastic wastes has taken on significance not far short of ultimate redemption.
The world consumes 100 million tonnes of plastic materials - 36.8 million tonnes in Europe, 5 million tonnes in the UK - and growing at 3 to 4 percent each year [1, 2]. The largest single sector, 37.3 percent, is in packaging. There are about 50 different groups of plastics with hundreds of different varieties.
The amount of plastic wastes generated annually in the UK was estimated at 3 million tonnes in 2001. Although all types of plastics could be recycled, only 7 percent actually were. The rest were buried in landfills (80 percent) or incinerated (8 percent). Most plastics are non-biodegradable, which means they take a long time to break down naturally.
Significant amounts of fossil fuels are required to make plastics, both as a raw material and as energy for manufacture. About 4 percent of the world’s annual oil production is used for as raw material and another 3-4 percent for manufacture.
Plastics manufacture requires a lot of water, produces waste and greenhouse gas emissions, and involves using harmful chemicals, especially with polyvinylchloride (PVC), the second most common kind of plastics in the world, where further toxic chemicals are generated during manufacture [3,4]. Burying plastic wastes in landfills or burning them in incinerators create still more hazards for health and the environment (see Box).
The best way to cut down on plastic wastes is to reduce use, to eliminate unnecessary packaging, and to reuse items such as plastic bags, toys, cosmetic bottles, etc. The next best way is to recycle.
PVC, polyvinyl chloride, is the second most commonly used plastic in the world, and causes the most problems for health and the environment. It is the largest source of dioxin when burnt in incinerators and in accidental fires in buildings. Dioxin is also created during the manufacture process, and toxic chemical additives are incorporated in PVC products.
The largest use of PVC is in building materials: cables, window frames, floors, walls, panelling, water and wastewater pipes, vinyl flooring, wallpaper, window blinds and shower curtains. It is in consumer articles such as credit cards, records, toys, office furniture, binders, folders, and pens, in the car industry as underseal, in hospitals for medical disposables, as imitation leather, and garden furniture.
The production of PVC involves transporting dangerous explosive materials such as vinyl chloride monomer (a carcinogen), and creating toxic wastes, notably ethylene dichloride tars. Tar wastes contain huge quantities of dioxins, which when incinerated or dumped, spread dioxins into the environment. Numerous additives are incorporated into the product, including softeners to make it flexible, heavy metals to stabilise colours, and fungicides. Dioxins are generated during manufacture, which end up in the process wastes, and sometimes in the product itself. Plasticisers are not bound to the plastic and can leach out over time; plasticisers in vinyl floors evaporate into the room. The most common plasticiser, the phthalate DEHP (Di(2-ethylhexyl)phthalate), is a suspected carcinogen, and over 90 percent are used solely to make soft PVC plastic, including baby toys and teethers. Since 1999, the European Union has prohibited phthalates in toys intended to be place in the mouth of children under three years of age [5].
The disposal of PVC creates more problems. If burned in open fires or incinerators, it releases an acidic gas along with dioxin. If landfilled, it releases additives that contaminate the groundwater, and landfill fires involving PVC are a further source of dioxin.
TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin), the most lethal member of the dioxin family, is a known human carcinogen and hormone disrupter, and is recognized as the most toxic synthetic compound ever produced. All humans and animals now carry burdens of TCDD and other dioxins in their bodies.
As much as 3.2 million tonnes of PVC are discarded as waste in the US every year, 70 percent consisting of packaging and bottles. PVC is difficult to recycle and contaminate other plastics. Concerned environmental groups want it to be phased out altogether.
Producing carrier bags from recycled rather than virgin polythene reduces energy consumption by two-thirds, produces only a third of the sulphur dioxide and half of the nitrous oxide; it reduces water use by nearly 90 percent, and carbon dioxide emission two and a half times. For every tonne of recycled polythene produced, 1.8 tonnes of oil are saved [1].
Recycling is done mechanically or chemically. In mechanical recycling, the waste plastics are sorted, then melted, shredding or turned into granules and moulded into new shapes.
In chemical recycling, the plastic polymers are broken down into their constituent monomers by heat treatment (thermal depolymerization), which can then be used again in refineries or petrochemical and chemical production. The UK does not operate any full-scale chemical recycling plants, as according to UK’s Department of Trade and Industry [2], capital investment requirements are much higher than for mechanical recycling plants (but see “Waste plastics into oil”, this series).
Despite the wide range of recycled plastics applications, the actual tonnage of waste plastic returned to the material cycle is relatively small. Currently, recycled plastics are rarely used in food packaging – the biggest single market for plastics – because of concerns about food safety. Another constraint on the use of recycled plastics is that, to be economically viable, plastic processors require large quantities of recycled plastics manufactured to tightly controlled specification at a competitive price compared to the virgin polymer.
The 1994 European Union Directive on Packaging and Packaging Waste 94/62/EC (the Packaging Directive) aimed to establish producer responsibility for packaging waste. The directive was implemented in the UK through the Producer Responsibility Obligations (Packaging Waste) Regulations 1997 and the Packaging (Essential Requirements) Regulations 1998. The former sets targets for the recovery and recycling of packaging wastes, including plastics packaging waste. The UK government published the national packaging recycling and recovery targets for 2004 and beyond. These required 21.5 percent of plastics waste to be recycled by 2004, rising to 23.5 percent by 2008.
The Waste and Resources Action Programme (WRAP) was established in the UK in 2001 to promote sustainable waste management. WRAP’s particular focus is creating stable and efficient markets for recycled materials and products.
WRAP runs a specific programme on plastic wastes. It set a target to increase mixed plastic reprocessing by 20 000 tonnes by 2003/2004, which has yet to be met [6]. Its target for 2004/2006 is to work with the wider plastics industry to increase the acceptance of recycled plastic throughout the supply chain, to deliver an additional 20 000 tonnes of domestic plastic bottle recycling capacity, and to ensure an additional 11 000 tonnes of non-bottle plastics are recycled.
UK’s Department for the Environment, Food and Rural Affairs has put out an action plan for a nationwide farm plastics collection and recovery scheme last year, and Waste Management Regulations will apply to agricultural waste in 2005 [7]. Farms produce more than 80 000 tonnes of waste plastic a year, such as fertiliser bags, animal feed bags and agrochemical containers, silage films, crop covers and tunnel films. Burning waste plastics ether in the open or in a drum incinerator – the current disposal option for most farmers - may no longer be available in future.
But what really happens to the plastic packaging and bottles that the British consumer diligently places in the recycling bin for collection by the local authorities, and, more so, those that supermarkets, the biggest users, are supposed to be responsible for recycling?
It turns out that more than a third of the waste paper and plastic collected by British local authorities, supermarkets and businesses for recycling have been sent 8 000 miles to China [8]. Exports to China are running at 200 000 tonnes of plastics rubbish a year. UK’s supermarket chains, some of the largest generators of plastic packaging waste in Britain, are getting their recycling done in China. Environmental groups and Members of Parliament were shocked at the scale of the trade. No studies have been done on the environmental costs of shipping wastes to China.
Article first published 24/11/05
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