Bad Science. Ben Goldacre

feet are filled with special ‘pores’ (discovered by ancient Chinese scientists, no less); you put your feet in the bath, the toxins are extracted, and the water goes brown. Is the brown in the water because of the toxins? Or is that merely theatre?

      One way to test this is to go along and have an Aqua Detox treatment yourself at a health spa, beauty salon, or any of the thousands of places they are available online, and take your feet out of the bath when the therapist leaves the room. If the water goes brown without your feet in it, then it wasn’t your feet or your toxins that did it. That is a controlled experiment: everything is the same in both conditions, except for the presence or absence of your feet.

      There are disadvantages with this experimental method (and there is an important lesson here, that we must often weigh up the benefits and practicalities of different forms of research, which will become important in later chapters). From a practical perspective, the ‘feet out’ experiment involves subterfuge, which may make you uncomfortable. But it is also expensive: one session of Aqua Detox will cost more than the components to build your own detox device, a perfect model of the real one.

      You will need:

      • One car battery charger

      • Two large nails

      • Kitchen salt

      • Warm water

      • One Barbie doll

      • A full analytic laboratory (optional)

      This experiment involves electricity and water. In a world of hurricane hunters and volcanologists, we must accept that everyone sets their own level of risk tolerance. You might well give yourself a nasty electric shock if you perform this experiment at home, and it could easily blow the wiring in your house. It is not safe, but it is in some sense relevant to your understanding of MMR, homeopathy, post-modernist critiques of science and the evils of big pharma. Do not build it.

      When you switch your Barbie Detox machine on, you will see that the water goes brown, due to a very simple process called electrolysis: the iron electrodes rust, essentially, and the brown rust goes into the water. But there is something more happening in there, something you might half-remember from chemistry at school. There is salt in the water. The proper scientific term for household salt is ‘sodium chloride’: in solution, this means that there are chloride ions floating around, which have a negative charge (and sodium ions, which have a positive charge). The red connector on your car battery charger is a ‘positive electrode’, and here, negatively charged electrons are stolen away from the negatively charged chloride ions, resulting in the production of free chlorine gas.

      So chlorine gas is given off by the Barbie Detox bath, and indeed by the Aqua Detox footbath; and the people who use this product have elegantly woven that distinctive chlorine aroma into their story: it’s the chemicals, they explain; it’s the chlorine coming out of your body, from all the plastic packaging on your food, and all those years bathing in chemical swimming pools. ‘It has been interesting to see the colour of the water change and smell the chlorine leaving my body,’ says one testimonial for the similar product Emerald Detox. At another sales site: ‘The first time she tried the Q2 [Energy Spa], her business partner said his eyes were burning from all the chlorine that was coming out of her, leftover from her childhood and early adulthood.’ All that chemically chlorine gas that has accumulated in your body over the years. It’s a frightening thought.

      But there is something else we need to check. Are there toxins in the water? Here we encounter a new problem: what do they mean by toxin? I’ve asked the manufacturers of many detox products this question time and again, but they demur. They wave their hands, they talk about stressful modern lifestyles, they talk about pollution, they talk about junk food, but they will not tell me the name of a single chemical which I can measure. ‘What toxins are being extracted from the body with your treatment?’ I ask. ‘Tell me what is in the water, and I will look for it in a laboratory.’ I have never been given an answer.

      After much of their hedging and fudging, I chose two chemicals pretty much at random: creatinine and urea. These are common breakdown products from your body’s metabolism, and your kidneys get rid of them in urine. Through a friend, I went for a genuine Aqua Detox treatment, took a sample of brown water, and used the disproportionately state-of-the-art analytic facilities of St Mary’s Hospital in London to hunt for these two chemical ‘toxins’. There were no toxins in the water. Just lots of brown, rusty iron.

      Now, with findings like these, scientists might take a step back, and revise their ideas about what is going on with the footbaths. We don’t really expect the manufacturers to do that, but what they say in response to these findings is very interesting, at least to me, because it sets up a pattern that we will see repeated throughout the world of pseudoscience: instead of addressing the criticisms, or embracing the new findings in a new model, they seem to shift the goalposts and retreat, crucially, into untestable positions.

      Some of them now deny that toxins come out in the footbath (which would stop me measuring them): your body is somehow informed that it is time to release toxins in the normal way—whatever that is, and whatever the toxins are—only more so. Some of them now admit that the water goes a bit brown without your feet in it, but ‘not as much’. Many of them tell lengthy stories about the ‘bioenergetic field’, which they say cannot be measured, except by how well you are feeling. All of them talk about how stressful modern life is.

      That may well be true. But it has nothing to do with their foot bath, which is all about theatre: and theatre is the common theme for all detox products, as we will see. On with the brown goo.

       Ear candles

      You might think that Hopi Ear Candles are an easy target. But their efficacy has still been cheerfully promoted by the Independent, the Observer and the BBC, to name just a few respected news outlets. Since these people are the authoritative purveyors of scientific information, I’ll let the BBC explain how these hollow wax tubes will detox your body:

      The candles work by vaporising their ingredients once lit, causing convectional air flow towards the first chamber of the ear. The candle creates a mild suction which lets the vapours gently massage the eardrum and auditory canal. Once the candle is placed in the ear it forms a seal which enables wax and other impurities to be drawn out of the ear.

      The proof comes when you open a candle up, and discover that it is filled with a familiar waxy orange substance, which must surely be earwax. If you’d like to test this yourself, you will need: an ear, a clothes peg, some Blu Tack, a dusty floor, some scissors, and two ear candles. I recommend OTOSAN because of their strapline (‘The ear is the gateway to the soul’).

      If you light one ear candle, and hold it over some dust, you will find little evidence of any suction. Before you rush to publish your finding in a peer-reviewed academic journal, someone has beaten you to it: a paper published in the medical journal Laryngoscope used expensive tympanometry equipment and found—as you have—that ear candles exert no suction. There is no truth to the claim that doctors dismiss alternative therapies out of hand.

      But what if the wax and toxins are being drawn into the candle by some other, more esoteric route, as is often claimed? For this you will need to do something called a controlled experiment, comparing the results of two different situations, where one is the experimental condition, the other is the ‘control’ condition, and the only difference is the thing you’re interested in testing. This is why you have two candles.

      Put one ear candle in someone’s ear, as per the manufacturer’s instructions, and leave it there until it burns down.* Put the other candle in the clothes peg, and stand it upright using the Blu Tack: this is the ‘control arm’ in your experiment. The point of a control is simple: we need to minimise the differences between the two set-ups, so that the only real difference between them is the single factor you’re studying, which in this case must be: ‘Is it my ear that produces the orange