Monday, July 07, 2008

To spray or not to spray

The difference between hazard and risk may seem academic or bureaucratic to the average citizen, but the shift in emphasis can have profound impacts on food safety as a recent decision by the European Parliament makes clear. By placing the burden of proof on the assessment of hazard before a pesticide can be used, Parliament appears to be putting the consumer's interest before that of the pesticide manufacturer's bottom line.

It will be interesting to see how this law is administered and what, if any impacts it will have on the price of produce. (GW)

A balance of risk


July 3, 2008

Pesticides keep food edible and cheap. On the other hand they are, by definition, poisonous. Europe's legislators thus face a dilemma

What is the difference between risk and hazard? Quite a lot, it seems, if you make or use pesticides. Everybody hates them (dangerous, unnatural things). But everybody likes their benefits (cheap and unblemished food). Sensibly regulating their manufacture and use is thus a minefield—but one that Europe’s politicians and bureaucrats are now attempting to cross without getting blown up.

The difference between hazard and risk, in this context, is that hazard is something you measure in a laboratory by finding out how much of a substance you need to kill or injure an experimental animal. Risk is something you measure in the real world. Risk depends not just on how toxic a chemical is, but on how it is actually used, how much of it is used and how often it is used. At the moment, Europe’s rules on pesticides are based on risk. However, a piece of legislation regulating plant-protection products, which is awaiting its final reading in the European Parliament later this year, will shift the basis of the law towards an assessment of hazard.

The legislation’s supporters claim it will lead to some of Europe’s most hazardous chemicals being withdrawn from the market. Wolfgang Reinert, an official at the European Commission’s directorate on Health and Consumers, says the new rules embrace the philosophy that something should be for sale only after the producer has proved it can be used safely.

Many agricultural scientists, however, argue that the change will have widespread, alarming consequences for farming, and will lead to further increases in food prices at a time when they are already uncomfortably high. ADAS, a British environmental and rural consultancy, has produced a report which says even the lowest-impact proposals would reduce food production by a quarter. In January an Italian report came up with a similar figure.

The threat to the use of pesticides is certainly serious. Depending on exactly how it is enacted, the legislation could outlaw all but one of the pyrethroids, a widely used class of insecticides; triazole, a fungicide used to protect cereal crops; and dithiocarbamate, a herbicide that controls a cereal-strangling weed called black grass. Yet all of these hazardous substances pose little risk if used properly.

Not surprisingly John Atkin, the head of the crop-protection part of Syngenta, a Swiss agrichemical and seed company, believes the changes are wrong. As he puts it, “current regulations are tough and we have already reached a point where some useful compounds, particularly for minor crops, have been lost, to the detriment of agricultural productivity.” (The minor crops in question include leeks, green beans and flower bulbs.) He adds that even under the existing rules some 700 substances have disappeared from the market, out of an original total of around 1,150.

Others without a commercial axe to grind agree with him. Ian Dewhurst, the principal toxicologist at the British government’s Pesticide Safety Directorate, points out that by failing to think about real-world risks, the European Union may end up acting against the wrong pesticides. It is not merely that the EU will probably ban what is, in practice, safe, but also that it might let through what is causing the most harm. Ian Denholm, head of plant and invertebrate ecology at Rothamsted Research, an agricultural institute in Britain, agrees, and judges that the present system, founded on science-based risk-assessment, is a “rigorous gold standard”.

The counter-argument is that, gold standard or not, the existing legislation (which was drafted in the late 1980s) is not working. As the chart shows, the share of food samples that exceed the maximum residue limits (MRLs) in Europe has remained constant for many years. Elliott Cannell, a spokesman for the Pesticide Action Network, an environmental group based in London, reckons the average European probably eats food contaminated with pesticides at least once a fortnight. The virtue of a risk assessment is that it captures what happens in the real world. If it fails to capture the actual threats to health, as these results suggest is happening, then it is failing to do its job.

Vyvyan Howard, a toxicologist and pathologist at the University of Ulster, and a supporter of the reform, also reckons that the existing system is not as good as it claims to be. He says it assesses exposure on a complex model of the world that is not always correct. “We know,” he says, “we get pesticides turning up where we don’t expect them.” He points to the example last month of gardeners in Britain being warned not to eat home-grown vegetables after manure they might have used became contaminated with a herbicide called aminopyralid.

The new system, according to Dr Howard, is based on science, but with pragmatism. The idea is to reduce the overall toxicity of the entire armory of pesticides. The new criteria would remove the most hazardous products from the food chain altogether. He believes this is particularly important for protecting fetuses, whose development is especially susceptible to disruption by outside chemical signals.
Just dilute before use

Science, however, is one thing. Politics is another. In response to the sceptics’ concerns, Europe’s agriculture ministers met on June 23rd to hammer out a compromise that will allow any country that feels it cannot replace a particular pesticide to ask permission to continue to use it. This has angered green groups and it has pleased neither agricultural scientists nor the British government. The exemption, Dr Denholm reckons, is “totally worthless”. The job of obtaining an exemption, he says, is too bureaucratic and could involve as much as two years of consultation.

One lesson from all this is that you cannot please all of the people all of the time. Cheap, pesticide-free food is probably an unachievable objective. The other lesson, however, is that science—so often seen as a way of arriving at clear-cut answers—is itself a process of muddling through to the truth. Hazard assessment has a certain purity, but that purity is often irrelevant to real risk. On the other hand, a true risk assessment is impossible, since not all of the variables can be identified, let alone measured and modelled.

But perhaps there is one lesson that science still can offer the politicians. It is this: by all means do the experiment and find out. But, if the experiment fails, have the guts to admit you were wrong and try something else. Politics being what it is, the new legislation is certain to be introduced. If it turns out to be a costly mistake, it should not be allowed to last.


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