Dr Eamonn Butler investigates whether recycling certain materials is actually worth the effort. If one looks in closer detail of how these materials are actually created, they may be just as, if not more harmful, to the environment than the materials we have substituted.
A four-year study by the Environment Agency has confirmed what many of us, with our back-of-the-envelope calculations, had already worked out: that disposable nappies are no worse for the environment than washable ones.
It might seem intuitively obvious that washables are best. You just wash and re-use them, instead of throwing them into a plastic bag and letting them mount up at landfill sites, leaking methane into the air and other unmentionables into the soil. But when the agency looked at the whole life-cycle of washables and disposables, it found "little or no difference" in the environmental impact.
After all, washing nappies requires water. You need gas or electricity to boil it. You use bleach and detergent, which goes down the drain and into our waterways.
Disposable nappies are certainly bulky to transport but the cotton in washable ones is flown here over long distances from China, Pakistan, or the United States. If you send washable nappies to the laundry, you have to think about the pollution, congestion, accidents and noise caused by the laundry van.
Add it all up, and disposables come out no worse. Which at least proves something else we had long suspected - that the armies of Real Nappy Officers appointed across the country in Gordon Brown's public jobs binge are themselves disposable.
A lot of the modern recycling religion turns out to be pure garbage. When you've finished with a polystyrene cup and are about to pitch it into the bin, you probably feel faintly sinful, and embarrassed that you didn't use one of those virtuous ceramic mugs.
Well, don't be. It takes a lot more energy to make that ceramic mug; and then each washing uses more energy, plus water and detergent. The Canadian chemist Martin Hocking calculated that you would have to use the mug 1,000 times before the energy consumed per use fell below that of the foam cup. And of course if you break it before then, it's no contest. And you are much less likely to pick up nasty bacteria from a foam cup.
Aluminium drink cans, though, certainly are worth recycling. Re-working the metal uses just a fraction of the huge amount of energy that is required to process bauxite into aluminium, and to mine it in the first place.
But sometimes the way we do that recycling is so wasteful it is almost laughable. My local authority has a recycling plan, so now we all have three plastic bins, which themselves are no great beautification of the environment. But the recycling commandments are complicated and people often put the wrong things in each one.
So when the dustcart comes round, the driver sits there (revving the engine, pumping out diesel fumes and holding up the traffic), while another guy sorts out our rubbish into the various compartments. Human time is a more precious resource than old bottles; but here we are, just wasting it.
Families in Mexico City throw out far more rubbish than families in the United States. That is because more of their food is unprocessed: it does not keep, and much of it is unusable. The outer leaves of American supermarket cabbage, the excess fat on the meat, or the skins of the oranges used for juicing, all go for animal feed.
In Mexico such things just rot in the rubbish: more material needs to be transported into people's homes and then out again to the rubbish dumps.
The plastic packaging of American food also ends up in landfill but it is thin, cheap and degrades easily. William Rathje, an Arizona archaeologist who (remarkably) digs through landfill sites, reports that plastic packaging and disposable nappies together occupy less than 2pc of landfill volume.
Paper, cardboard and other supposedly eco-friendly materials don't actually degrade well in airless dumps; plastic grocery bags are now so thin that 100 of them take up the same space as just 20 paper bags.
Juice cartons, too, take up about half the landfill space of the bottles they replaced. There was a time when bottles were expensive and we all took them back to the shop to claim our deposit. These days, we realise that by the time the bottles have been transported (diesel), washed (water, electricity) and sterilised (who knows what), it is a costly non-gain for the environment.
And what about all the trees that are cut down to make newspapers? Well again, to justify recycling you have to look at the whole life cycle of the process. Newspapers are covered in ink: getting rid of that costs money and also uses some pretty nasty bleaches.
Moreover, the more paper we recycle, the fewer trees are planted. People don't plant trees if they cannot sell the timber. And the fewer trees we have, the less of the greenhouse gas carbon dioxide is absorbed from the atmosphere. Recycle a ton of paper and you need 17 fewer trees, which I am told would have absorbed three tons of carbon dioxide over their lives.
Experts can argue about the exact figures in each case. But the good thing the Environment Agency has done, in its laborious four-year nappy review, is to show us that things which look environmentally virtuous at first sight may well turn out to be environmentally vicious on closer inspection.
We should recycle if it is rational, not because it is a religion.