What's more dangerous - the bute or the burger?

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understandinguncertainty.org was produced by the Winton programme for the public understanding of risk based in the Statistical Laboratory in the University of Cambridge. The aim was to help improve the way that uncertainty and risk are discussed in society, and show how probability and statistics can be both useful and entertaining.

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There is reasonable public outrage at possible criminal conspiracies to adulterate meat products with horsemeat, and additional concerns raised about the presence of the anti-inflammatory known as bute.

While not in any way questioning this concern about adulteration with a chemical compound, it is helpful to get a sense of magnitude. When bute was given as a human medicine, it was reported to be associated with a serious adverse reaction in 1 in 30,000 (over a whole course of treatment), but at a dose giving concentrations at least 4,000 times that arising from eating a diet of horse meat - see the excellent information from the Science Media Centre

So making all sorts of heroic assumptions about there being a linear-no-threshold response, we might very roughly assign a pro-rata risk of a serious event as 1 in 100,000,000 per burger.

Compare that with the risk from the meat itself. There is good evidence that red meat consumption is associated with an increased risk of bowel cancer, and specifically a large recent study from Harvard associated a daily habit of 80g (3.5 oz) of red meat with an increased all-cause mortality rate of 13% - I recently showed in this British Medical Journal paper that this was as if, pro-rata, each portion of red meat was associated with ½ hour loss in life-expectancy, around 1,000,000th of a young-adult’s future life.

So my rough guess is that for a burger made out of horse-meat containing bute - or indeed any kind of red meat - the burger itself carries around 100 times the apparent risk of the bute. Even taking into account that the bute reaction would occur quicker than any harm from the red meat, this still is a notable disparity.

Of course I know very well that people, including myself, feel very differently about risks that are chosen as part of daily life, and appear ‘natural’, to those imposed by outside (probably criminal) agencies and involve unnatural substances. I fully respect those feelings, but I still believe some perspective is valuable.


The risks from the anti-inflammatory drug phenylbutazone are unlikely to be linear with dose, especially the risks of developing aplastic anemia and thus if anything I agree 1 in 100,000,000 is probably too high an estimate. However I do think that it is reasonable to assume that evidence that a burger has been adulterated with a chemical or DNA that you are testing for might indicate that there is also an increased risk of adulteration or poor handling of the meat with other things that you aren't necessarily testing for. After all if a criminal is prepared to carry out such a fraud on the public, how concerned are they likely to be about food quality or standards in general? So perhaps the horse and bute contaminated burger is of a significantly greater risk to the public than is an unadulterated beef burger, but the risks may be for another associated reason. (As a declaration of interest, I've been a vegetarian for nearly 20 years.)

If we replace the word 'bute' with 'sewage sludge', the whole thing gets even more confusing. I'm not sure that an understanding of risk would help, because the disgust level is not related to it (assuming for the moment that there is no risk from eating sludge contaminated food (which is probably vanishingly small in a cooked, processed food, in my opinion)). And so we're left in the confusing situation where we are perfectly happy to eat food when we don't know what is in it. The more information we have, even if that information indicates that the risk is vanishingly small, the more disgust we feel. Even though the risk attached to other foods (for example eating baked potatoes which may have somehow been slightly contaminated with faeces) might be much higher. I don't think we really want to know, hence we only ever get worked up by things when we are forced to know them.

Both the excellent comments above show that perceptions about risk are about far more than statistics and calculations, but are affected by deeply-held feelings of trust and taboo. The idea that 'we don't really want to know' is particularly relevant for food: most non-vegetarians would not want to see the food they eat being killed and prepared, or even how it lived its life, let alone see into the kitchens of some restaurants.

Absolutely, and most vegetarians ALSO don't want to see how these animals are treated! Although, having already decided on their behaviour (and assuming, as I do, that it's unproblematic to be vegetarian), it's less important for the vegetarians to see.