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on his way back from the pub! It could be older than everything in your street–all the trees, the houses, the cars, the people… everything. Now of course that’s not actually true because plastics weren’t invented in 1511. But roll the clock forward five hundred years from now, to 2511, and it’s quite possible that the person living in what’s now your house will dig up the garden and find bits of plastic you left behind. Or that a 25th-century Tony Robinson will make archaeology programmes on TV about sifting through all the random bits of plastic in a 21st-century landfill.

But  we’re recycling so much more plastic now?

Or are we? Over 90 percent of the plastic stuff we buy still ends up in a landfill. That’s bad for all kinds of reasons. Landfill is just a more polite word for litter; it’s litter on a grand scale! Not only that, it’s such a waste. Most plastic comes from petroleum–and we know oil is going to run out sooner or later. Apparently, something like 200,000 barrels of oil a day are used to make plastic for packaging, just in the USA–a huge waste, and most of it going to landfill in a matter of days or weeks. There’s also the question of energy. It takes far more energy to make disposable plastic things than it does to use the same things over and over again. Recycled plastic is much better than brand new plastic: it saves about two thirds of the energy used in manufacturing. But, quite frankly, recycling is only a little bit better than throwing things away. It’s far better not to use plastic at all than to recycle it. It’s much better, for example, to have a reuseable aluminium water bottle that you fill up from the tap each day than to buy plastic bottles of water and then very conscientiously recycle them. Where do they go after you’ve recycled them? It takes a lot of energy to transport them, melt them down, and turn them into new plastic products that may (or may not) be recycled. Far better to eliminate the plastic completely if you can.

Do plastics have to be so bad for the environment?

Absolutely not. The thing to remember about plastics is that humans created them. Chemists in laboratories engineered pretty much all these polymers and designed them to do very specific jobs. There’s nothing random or accidental about it, so why should there be anything random or accidental about how we dispose of them? In other words, there’s no reason why chemists can’t engineer plastics that can be disposed of more easily. In fact, they’re already doing just that. We’ve had biodegradable plastics for several decades and now the industry buzzword is “bioplastics”: plastics made from more natural ingredients that break down much faster when we dispose of them.

That sounds brilliant! How do they work?

A really good example is the kind of packaging you now find on many sandwich containers. Go back ten or twenty years and take-away sandwiches always came in plastic triangles that you simply threw away. Who knows what happened to them? Well most of them–hundreds of millions of them–are sitting in landfills under our feet. What a waste! And what a disgrace! Buy yourself some sandwiches today and it’s a very different story. You’re probably going to get a cardboard container (which is easy to compost or recycle) with a thin window made of what looks like ordinary, thin plastic. But it’s more likely to be a bioplastic based on corn starch (the stuff you put in sauces to thicken them up). The bioplastic has these little chunks of cornstarch embedded in it. As it picks up moisture, the starch swells up (just like your sauce thickens) and cracks the plastic into tiny fragments that break down more quickly–typically in just a few months. Things like greetings cards are now being packed in the same stuff. Other bioplastics (ones that don’t use cornstarch) are designed to be broken down by sunlight, water, or high temperatures.

Does bioplastics have any drawbacks?

It would be great if all the plastic we couldn’t avoid using was either reused in some way or recycled. Realistically, though, that’s never going to happen: most bioplastic is going to end up in a landfill, just like ordinary plastic. So we still need to think about that very carefully. Some bioplastics disappear very cleanly in landfills. Because they’re made from plants, they absorbed carbon dioxide when they grew in the first place and they release that carbon dioxide again when they break down–so effectively, ignoring the energy used in manufacturing, they’re carbon neutral: they don’t add to global warming. Other bioplastics break down and release methane, which is a really powerful greenhouse gas (much worse than carbon dioxide). That’s a serious issue. Some also leave a toxic residue in the landfill, which could cause water pollution or soil contamination. Another problem is that bioplastics can’t be recycled the same way as ordinary plastics so if they all get mixed in together in a recycling container, you can end up with a huge pile of unprocessable waste that has to go to a landfill. There are other issues too. Some bioplastics are described as “compostable”, but they only compost in the kind of high-temperature digesters operated by councils, not on your average, low-temperature, home compost heap.

So not really a complete solution?

Definitely not. You have to go back to what we were saying right at the beginning–about how many different kinds of plastic we use and in how many different ways. You can’t really make a plastic washing up bowl from bioplastic–it would slowly disintegrate before your eyes! But what else are you going to make it out of? And if you accept that it’s not something you’re going to keep forever, what happens to it when you throw it away? Ditto with a toothbrush: it’s something you have to throw away and replace (if you want to keep your teeth).