Carcinogenic concerns

Food panics are far worse for us than modern farming, argues Julian Morris

No technology is risk-free. More importantly, experience suggests that while new technologies bring with them new risks, these tend to be less serious than the risks they replace. Take pesticides: insects represent a significant threat to crop productivity, and if unchecked they will typically consume anything from 20 to 80 percent of a crop. Synthetic pesticides prevent such losses by targeting the crop-consuming insects. By using synthetic pesticides, farmers have been able to increase agricultural output dramatically without increasing the area of land under cultivation. As a result, we are better fed than at any time in history. If the world were to produce the same amount of food without synthetic pesticides, millions of acres of wilderness would have to be put under the plough - hardly an environmentally preferable option.

In spite of this, environmentalists claim that pesticides are harmful both to health and the environment. In her bestselling 1962 book, Silent Spring, Rachel Carson claimed that synthetic pesticides were killing bird species. While there is some evidence that DDT, the primary focus of Carson's wrath, caused a decline in some populations of some raptors, the majority of her claims were refuted by subsequent research. DDT and other organochlorine pesticides have relatively little impact on birds and are not known to have any significant impact on humans or other mammals.

The campaign against organochlorine pesticides led to an increase in the use of organophosphate pesticides, which are known to be toxic to mammals at high doses. Nevertheless, at the low doses at which pesticides are present as residues on food, they are not a health threat.

Environmentalist claims that pesticide residues are carcinogenic are based on linear extrapolations of high-dose rodent experiments. Bruce Ames, professor of biochemistry and molecular biology at the University of Berkeley and among the most highly regarded cancer experts in the world, points out that such extrapolations ignore the fact that animals are constantly exposed to natural carcinogens, and that our immune systems have evolved to deal with the kind of low-dose exposure likely from pesticide residues. The fact that there are more known rodent carcinogens in a single cup of coffee than in an entire year's worth of pesticide residues should also caution scepticism about the health effects of pesticides - and Professor Ames still enjoys an espresso after lunch.

What about fertilisers? In the days before synthetic fertilisers, farmers typically used a combination of crop rotation and manure spreading to replace nutrients absorbed from the soil by crops. These old technologies are now being hailed as the 'sustainable' alternative to synthetic fertilisers and are an essential part of 'organic' farming. But such techniques are less sustainable and present a greater danger to health than synthetic fertilisers.

Crop rotation entails growing plants that replace lost nutrients (for example, by fixing nitrogen from the air) and leaving fields fallow. But growing certain crops because of their nutrient-giving qualities alone inevitably results in a reduction in efficiency. Leaving fields fallow has the additionally adverse consequence of encouraging soil erosion: bare earth is more susceptible to both the wind and the rain.

Spreading manure on land, even if that manure is treated, runs the risk that plants may be contaminated with bacteria. Dennis Avery, director of the Centre for Global Food Issues, analysed data produced by the US Centers for Disease Control and found that people who consumed organic and natural food were eight times more likely to become infected with Escheria coli 0157:H7, a potentially deadly bacterium.

By contrast, synthetic fertilisers seem positively benign. Modern satellite-based guidance systems mean that they can be applied with great precision, so that yields can be optimised and waste cut to a minimum. Not all farmers employ such methods, with the result that there is fertiliser run-off into nearby watercourse, damaging the aquatic life. But commercial necessities will drive such efficiency improvements.

Another alternative promoted by environmentalists in their bid to rid the world of modern technology is free-range farming. Justifications range from claims that the animals are healthier to claims that they are happier. Both claims are highly contentious.

Comparisons made for the magazine Consumer Reports in 1998 found that free-range chickens were three times as likely to be infected with salmonella as battery-farmed chickens, as well as being more likely to be infected with listeria and campilobacter.

Measuring 'happiness' in humans is difficult enough. Measuring happiness in animals is nigh on impossible. Among other things, animals are not known for their ability to perform psychometric tests. However, proxy measures, such as the number of eggs produced by hens, might provide some insights. It is supposed that happier hens should produce more eggs because happiness is brought about when their environment is favourable to the rearing of chicks. Intriguingly, research suggests that battery chickens can be at least as productive as their free-range counterparts under the right conditions - which might entail, for example, having a Mozart cantata playing in the background - indicating that even the welfare claims about free-range animals are open to question.

Studies do suggest that chronic anxiety has a detrimental effect on the body's immune system, rendering us less able to fight diseases from the common cold to cancer. By encouraging us to fear the food we eat, environmentalists contribute to our anxiety - and so are probably more carcinogenic than anything we eat.

Julian Morris is co-director of the Environment Unit at the Institute of Economic Affairs and co-editor of Fearing Food: Risk, Health And Environment