David Fisk considers the concept of risk

To protect bystanders from pesticide sprays, the Royal Commission on Environmental Pollution (RCEP) has recommended a statutory 5m cordon.(1) The Advisory Committee on Pesticides (ACP) thinks it unnecessary.(2) Just another expert dispute? As ever, things are a little more complicated.

In determining the low dose health effects of pesticides we cannot be truly scientific, because the definitive experiments are blatantly unethical. It is a matter of guessing the truth, aided by some scientific insight, and knowing what it is we are supposed to be protecting.

In the event, with relations between the UK government and farmers already at a low ebb, the government had no appetite for more precautionary measures in a sector not famous for precautionary compliance. It concurred with the ACP. Many might see that as a pragmatic, if interim, position.

Calculating the risk

Now suppose, as a worried bystander or farmer, you were to try to re-compute the risk yourself.

You would start with a reproducible effect in the laboratory on a test mammal. You would need a factor to translate that dose to a human scale. You would need another factor for genetic variability in the general population. Then you would need to calculate how that dose comes about.

But if you have got this far, you have had to make several non-scientific decisions. Are you protecting babies or grown men? How far a genetic outlier are you protecting? Fundamentally, were you intending to protect the rights of the neighbours to use their property when and how they like? In that case, the dose is derived from the worse case event – let us say a young child with exposed skin playing on the ground. Or are you reducing accidents associated with farming, effectively giving the farmer a property right up to the boundary? In that case, you would need to know in what proportion of all sprays a small child would be in the path of pesticide when the wind gusted.

Assessment problems

The fundamental property rights are not pre- established. The RCEP approached the problem with the traditions of urban environmental legislation, ACP with the traditions of worker safety. So different guesses as to what is appropriate precaution are to be expected.

Matters are made worse because legislators are not consistent on the status of psychosomatic reactions. In worker safety you would be advised to take another job. In food standards you spray the crop with pesticides just so customers can avoid eating the odd nutritious maggot. For psychosomatic reactions we have no analogue animal model to set up in the laboratory, so even the first step of the risk assessment is problematic.

Finally, you would also need to compute the likelihood that the government could respond to new evidence of harm. On the evidence presented by the detailed responses to RCEP recommendations, this does not look a very high number.

Government response

The detailed technical responses from Defra (the Department for Environment Food and Rural Affairs)(3) to the RCEP read like pure, unreconstructed, pre-Philips-Inquiry MAFF (Ministry of Agriculture, Fisheries and Food). In some cases, as far as I could judge, they do not actually directly answer the corresponding RCEP recommendation. Indeed, in a response that was supposed to assure us that all-was-well-in-Wiltshire, the Ministry of Defence (MoD) has been allowed to elbow in a critique of a small appendix – itself only a short précis of a Congress Report on the Gulf War Syndrome (which the MoD apparently needs to assure us does not exist). The hapless appendix is not directly related to any of the recommendations and only referenced twice in passing in the main text. Presumably the critique is either to convince conspiracy theorists that Gulf War Syndrome considerations were relevant to forming the overall response (ouch!) or, much more likely, to demonstrate that the MoD does not believe that Cabinet Office guidance on communicating risk applies to it. 

Back at the farm

So what are farmers and their neighbours to do? The Nobel prize winner Ronald Coase pointed out over 30 years ago(4) that if the land rights are clear, then you could cut out the public sector altogether in cases like this and leave the parties to strike a financial bargain. With a Texan judge behind you (English judges can be a little flaky on restrictive covenants), just buy as much cordon as suits your bill fold. Otherwise wise farmers, facing encroaching urbanisation in an island determined to overcrowd itself, might just leave all this behind and get their spraying contractors to start mugging up on the Green Code and buffer zones.

References

1. RCEP report: Crop Spraying and the Health of Residents and Bystanders
2. ACP commentary on the RCEP report
3. Government response to the RCEP report
4. Wikipedia information about Coase Theorem

David Fisk is Professor of Engineering for Sustainable Development at Imperial College London