Synthetic chemicals: killing us softly?
Baseless scare stories are contaminating our enjoyment of food.
It’s the silly season, which is usually the time for stories about how bad eating is for us. Unless, that is, we’re sensible and informed enough to eat organic food. Aficionados will tell you that organic food is natural and therefore better for you. The nub of the argument is that organic produce is untouched by chemicals (a word that sends a shiver down the spine of any self-respecting foodie). In particular, no pesticides are used, so the organic vegetable is therefore full of goodness, and you can eat it with a warm glow of self-satisfaction.
To paraphrase Blackadder, there’s one tiny flaw in this argument: it’s utter rubbish. Everything we eat is made of chemicals: they just don’t happen to be manmade. Many of the minor components of plants are in fact natural pesticides: they repel or harm insects or other creatures that want to make a meal of them. What is more, using the standard ways employed by scientists to test toxicity or carcinogenicity (eg, feed increasing amounts of a substance to rodents until a level is reached where half of them die), many of these compounds can be shown to cause harm. But because they’re not manmade, we neither test them nor worry about them. When they are tested, they are found to be equally damaging to the health of rats as manmade pesticides (1).
Yet we seem to worry incessantly about the use of synthetic crop protection chemicals that have been extremely thoroughly tested. Yes, these are toxic and harmful if misused, but the risk is to farmers rather than consumers. And farmers are intelligent people who have been trained how to use pesticides correctly. Despite agricultural workers’ potentially much greater exposure to carcinogens than the general public, they actually have a lower incidence of cancers: in 11 out of 12 studies on farmers, covering some 300,000 subjects in total, cancer rates were found to be substantially lower than for the population as a whole (2).
There is no evidence that legal levels of pesticide residues cause health problems. During the past 50 years, as agriculture has become more intensive and use of pesticides increased, we have become healthier and longer-lived (3).
Of course, if you sincerely believe that synthetic chemicals pose a health risk, no amount of evidence will convince you otherwise. The standard response to the fact that there is no evidence of harm is: ‘more testing is needed.’ To figures that show a steady decline in the levels of pesticide residues detected (4), we hear: ‘what about the build-up over time; what about the “cocktail” effect?’
Cast your mind back to the Sudan 1 contamination that occurred earlier this year. A batch of chilli powder had been brightened up at source by the addition of this red dye. The dye is not allowed for food use, not because there is hard evidence of any hazard, but because it’s never been positively approved. The chilli powder was imported and used as an ingredient to make Worcester sauce, and this sauce in turn was used as a minor component of numerous processed food products. Clearly, the use of this dye was illegal: there was a failure of the system. But was there a real risk?
One article pithily summed up the extent of the ‘risk’: ‘To ingest Sudan 1 in the amounts that were shown to cause harm in rats, a human would have to consume Crosse and Blackwell’s Worcester sauce at the rate of three tons every day for two years.’ (5) But that doesn’t assuage fears: if something has been withdrawn ‘as a precautionary measure’ then it has been condemned.
Consumers can be made to feel frightened of their food if they are given misleading information by campaign groups and their accomplices in the media. Left to their own devices, most people choose food they like to eat and can afford. They don’t read labels. They don’t think about additives, or the conditions under which the food was packed. If there were fewer negative stories about food in the media, we would be no less safe, but a lot of people might worry a lot less.
Martin Livermore is a freelance science communicator, commentator and consultant. He is also an occasional blogger – see Out of step? and Rational Agriculture
(1) Paracelsus to parascience: the environmental cancer distraction, BN Ames and LS Gold, Mutat Res 447, p3-13, 2000
(2) ‘A critical assessment of organic farming-and-food assertions with particular respect to the UK and the potential environmental benefits of no-till agriculture’, A Trewavas, Crop Protection 23 p757-781, 2004
(3) For a good discussion of this, see The Skeptical Environmentalist, B Lomborg, 2001, p226-236
(4) See for example Pesticide levels ‘pose no threat’, BBC News, 29 June 2005
(5) ‘Food, poisonous food’, Sunday Telegraph, 27 February 2005
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