NIAB - National Institute of Agricultural Botany

Orson's Oracle

Over-precautionary principle?

Posted on 06/09/2016 by Jim Orson

Previous blogs have defined the difference between hazard and risk. Electricity is hazardous but the way we manage it means that it has a very low risk of doing harm. With pesticides, the level of risk is all about the dose likely to be received by operators, bystanders, customers and the wider environment. The way we manage pesticides can reduce the risk to acceptable levels for many pesticides hitherto classified as hazardous.

However, uniquely and for the first time, hazard cut-offs have been adopted in the current EU pesticide regulations, perhaps due to the over-zealous application of the precautionary principle. This means that however low the risk of using a particular pesticide may be, its registration will be refused or revoked if it has in any way been classified as a hazardous substance.

There are, of course, other hazards to human health involved in crop production. The most significant are the hazardous pathogens that occur in animal manures. The most prominent is E. coli, but salmonella and listeria can also be present. No one would dream of banning animal manures from crop production, despite these hazards.

The greatest risk of these hazardous organisms causing harm must be when manure is used just before or during the production of short-season crops which are consumed raw. There are guidelines for composting the manure before use, but things can go wrong. The best known example of things going wrong is the deaths caused by E. coli contamination of organic bean sprouts in Germany a few years ago. Over 40 people died and more had their long-term health ruined. In this and other cases of E. coli contamination, the risk management procedures either failed catastrophically or were not followed.

Possibly as a result of this particularly disastrous failure to provide safe food, the regulators appear to have increased their monitoring of hazardous pathogens in food. Last year the New York Times reported on the dramatic increase in product recalls of organic vegetables in the US, mainly due to contamination from animal manure derived salmonella and listeria. These pathogens can, at the very least, cause severe discomfort for the consumer. The data suggest, at least in some cases in the US, that the risk management of animal manures still needs tightening up. It is interesting that these pathogens did not appear to be an issue in conventionally produced food, whose main problem was undeclared allergenic constituents.

Over the last few decades there has not been a human death in the UK directly attributable to pesticides and in addition, I have not been aware of any proven chronic effects except, perhaps, from pesticides that were withdrawn a long time ago. Interestingly, a recently published study by Oxford University on the diets of more than 600,000 women over a decade, carried out before hazard cut-offs were introduced, suggests that eating organic food does not reduce the incidence of the wide range of cancers monitored. This suggests that rigidly applied risk management and not hazard cut-offs should also be appropriate to pesticides as well as animal manures.

Perhaps Brexit will provide an opportunity for the UK to make sure that the risk of harm from pesticides is assessed in the same manner as for other inputs used to produce food.

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