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Fantastic plastic

In today’s world of blacks and whites, plastic waste is becoming a major target both of environmentalists and policymakers, and the benefits are being forgotten. This is an unfortunate trend, but typical of the highly precautionary mind-set that has put so much pressure on synthetic chemicals in general and crop protection and agricultural biotechnology in particular. Without a balanced view of risks and benefits, there is a danger of throwing the baby out with the bathwater.

But it wasn’t always like that. As synthetic polymers became commercially available in large quantities from the mid-20th Century, they were seen as new wonder materials with a host of valuable uses. Where wood, paper, cotton, wool or glass had been the only raw materials available, polyethylene, nylon, PET, polyester and a host of other polymers came to compete.

In some cases, their claimed advantages were transitory. Those who remember drip-dry nylon shirts and sheets will not miss them. But in other cases, the changes were profound and long-term. Without polymeric resins, mdf (medium density fibreboard and its variants) could not have been made, everyday furniture would have been considerably more expensive and our reliance on mature trees much greater, for example.

There is one area in particular in which plastics have been highly successful, but also have created problems: packaging. Plastics can be moulded, shaped and printed to give packs that both protect food and other goods and make them attractive to us. However, the durability that is a plus in the distribution chain is a liability once the packaging has served its purpose. When discarded, many polymers are essentially indestructible, even if the packs they form physically break down into smaller pieces.

The particular focus today is on plastic waste in the oceans, brought into especially high profile via the BBC Blue Planet 2 series. If a national treasure like David Attenborough highlights a problem, people tend to take notice. As some marine creatures feed, they ingest tiny pieces of plastic, and these may increase the mortality of their young in particular, by diluting the nutritional value of their food. Some creatures may even become entangled in plastic bags.

There is also the sheer scale of the problem to consider. Because of the nature of ocean currents, there are some places in the open sea where waste tends to gather in quantity, with the ‘great Pacific garbage patch’ being the most widely known. Mental pictures of floating rubbish are, however, very wide of the mark. This is in effect a large area of sea in which tiny degraded pieces of plastic (and other materials) are concentrated, with little if any large pieces visible to the naked eye. But it is these tiny pieces that can be ingested and build up in the food chain.

The problem is a much more visible one on shorelines and land, where discarded rubbish accumulates until it is physically removed. This is unsightly and unpleasant but, by and large it presents little real hazard to wildlife.

At heart, the problem is one of human behaviour. A minority of people choose not to dispose of rubbish properly and drop it in the street or dump it from cars or boats. If we could eliminate this behaviour, then there would be no environmental problem. However, this is too much to hope for in most societies and, in any case, we have to find suitable ways of disposing of or reusing packaging once it has served its immediate purpose.

There are those who call for the use of plastic packaging to be ended. ‘Plastic free’ aisles may soon appear in supermarkets, and Iceland is the first food retailer to announce their intention to eliminate all plastic packaging from their own-label products. While this may sound fine in principle, in practice it would make shopping for many items much more difficult.

In many cases, when what may appear to be excessive packaging is eliminated, food waste is increased. Carefully packaged ripe fruit would be more likely to become unsaleable. Meat in a modified-atmosphere packaging would have a shorter shelf life. In many ways, food waste would be easier to deal with – it could serve as a fermentation substrate to make a range of useful products, or methane as a fuel – but the logistics of collection have not yet been devised and food waste is itself an emotive issue at present.

If there is still to be a large quantity of plastic packaging in circulation, an effective way of increasing collection rates is needed. Many countries already have a deposit scheme for plastic bottles, as well as glass ones. In the UK, deposits are rarely seen, but whether 5p on a bottle of drink would make a difference to the kind of person who doesn’t think twice about throwing an empty bottle into the hedgerow is a moot point.

In Singapore, litter-free streets are the rule because of fines for littering, which are enforced. In the UK, it is almost unheard of for someone to be prosecuted for casual littering, despite the penalties in law. But where there is already a litter problem, regular clear-ups plus education campaigns may be the only way to change public attitudes.

Although recycling rates have increased, not all plastics can be recycled and there is insufficient demand for some recycled material to make it worthwhile to recycle all of it. China has recently stopped dealing with British plastic, for example.  And ‘green’ plastics made from renewable raw materials (for example, various grades of polyethylene) do nothing for the waste problem.

In the short to medium term, we are left with just two practical solutions, neither of which is popular in today’s climate. One is landfill. Although out of favour, this cannot be completely ignored, particularly if the material buried is as inert as plastic. The other is incineration. Modern, high temperature incinerators produce clean exhaust gases and have the added advantage of recovering some of the energy inherent in plastics (and other materials) as heat. Combined heat and power plants can be very useful when situated in areas of high density housing.

The choices may not seem attractive ones, but realistically we are unlikely to see a major reduction in plastic packaging anytime soon. Given that, we have to find sensible and effective ways to deal with the waste problem. Efficient collection systems are a vital prerequisite, but in the present absence of viable ways to recycle the material, incineration must be regarded as a credible option.