Green with prejudice: why a fair hearing is needed for pesticides

Green with prejudice: why a fair hearing is needed for pesticides

by Martin Livermore
article from Friday 23, June, 2017

FOOD PLAYS A UNIQUE part in our lives. At minimum, it is essential for life, but it also has great cultural significance. For those of us lucky enough to live in peaceful, prosperous societies, eating can be an important source of pleasure rather than simply a means to keep us alive.

But eating is not entirely risk-free. The present-day surge in rates of obesity and type 2 diabetes is strongly related to the ubiquity of affordable food, and food poisoning of varying severity can still be an unpleasant fact of life. But, alongside these very real risks, many people choose to minimise other perceived or hypothetical risks and eat food they consider safer or healthier, which has led to a view of organic food being superior.

While choice of variety and freshness of produce can undoubtedly make food tastier and more enjoyable, there is no intrinsic reason why such quality cannot be delivered via ‘conventional’ farming and, indeed, it often is. Nevertheless, the ‘organic’ branding has proved to be very successful, despite there being no consistent, demonstrable differences in terms of safety or nutritional value.

A key part of the organic message is, of course, the eschewing of synthetic fertilizers and pesticides. The use only of animal and green manures is for environmental rather than safety issues (the environmental impact is actually not a black and white issue, but these arguments are for a separate occasion), but the refusal to use synthetic crop protection chemicals has a food safety component.

A strong association between the words ‘natural’ and ‘safe’ has become established in the general psyche, while ‘synthetic’ and ‘chemical’ are seen as hazard warnings. With the concept of dose-related risk being lost on the general public, the detection of even tiny amounts of pesticides is regarded as a risk to health. No amount of quoting Bruce Ames, talk of safety factors or analogies of drops in Olympic-sized swimming pools seems capable of changing this. It is a view based on emotion rather than rational argument.

While minimisation of risk for all concerned (with due regard for benefits) should always be the aim, the most recent formulation of EU pesticide regulations in terms of hazard is regarded by many scientists as an unnecessary step too far. The negative impacts on farmers and the food supply have been put forward as reasons to retain the previous risk-based regulations, but to no avail. The orthodoxy among regulators now is that pesticides must become ever safer.

A significant victory for the anti-pesticides brigade is the temporary banning of neonicotinoid insecticides, based on their unproven link with major declines in bee populations. The aim is now to make that ban permanent if possible. But an even bigger target for the campaigners is glyphosate, the world’s most widely used weedkiller, which has made a fortune for Monsanto under its Roundup brand.

Glyphosate has been attacked for many years because of hypothetical environmental damage. It is, however generally regarded as one of the most benign crop protection chemicals; it targets a particular biochemical pathway found in green plants, but has very low toxicity to animals. That doesn’t mean that it is not used in combination of adjuvants with higher toxicity, but that can be true of any crop protection chemical. In any case, the major suppliers and distributors have an excellent record of minimising risk and training spray operators.

Things changed when the International Agency for Research on Cancer (IARC), a part of the World Health Organisation, declared glyphosate to be a potential carcinogen in 2015. This category (2B) includes a wide range of common materials, including bitumen, titanium dioxide, carbon nanotubes, bracken, aloa vera extract, as well as doing carpentry, dry cleaning, printing or working shifts as a living. This is a lower risk category than many components of coffee, which have been shown to be mammalian carcinogens.

This re-categorisation was controversial but has, of course, been seized upon by campaigners who want to see glyphosate banned (the reasons for this are many and varied, with human safety not necessarily being the highest on the list). It has, not surprisingly, delayed the re-approval of the herbicide in the EU. Despite EFSA’s continued view that re-approval is justified, some MEPs are pressing for this to be refused.

However, a report this week from Reuters provides some interesting and important background to this issue (Special report: cancer agency left in the dark over glyphosate evidence). The key point is that the person who chaired the IARC meeting at which the decision was made – epidemiologist Aaron Blair – was aware of unpublished data that significantly weakened the case against glyphosate.

The Agricultural Health study was a large-scale study of about 89,000 farm workers and their families, capable of showing statistically significant links between a range of chemicals and various cancers. However, the published results did not include the work on pesticides, said to be “to make the paper a more manageable size”. Blair himself was one of the authors, and has testified that access to this data would probably have changed the committee’s decision.

Reuters asked for independent assessments. This is what they got:

Tarone [a retired statistician who had worked alongside Blair] said the absence of herbicide data in the published 2014 paper was "inexplicable," noting that volume of data had not been an issue in any previous published papers. He said updated AHS data and analyses on herbicides "should be published as soon as possible" to allow "a more complete evaluation of the possible association between glyphosate exposure and NHL risk in humans."

Spiegelhalter [Cambridge Professor of the Public Understanding of Risk] told Reuters: "In the drafts I saw, none of the herbicides, including glyphosate, showed any evidence of a relation" with non-Hodgkin lymphoma. He noted that the study was statistically strong enough to show a relationship for other pesticides - so had there been any link to glyphosate, it should have shown up.

The motivation for all this we can only guess at, but it seems that there is a predisposition among some scientists to damn pesticides unfairly. If evidence that glyphosate caused harm had remained unpublished, there would have been an outcry. We can only hope that scientific evidence wins out in this case. If not, a further dangerous precedent will have been set and farmers (and gardeners) will have lost an extremely useful weedkiller. 

Martin Livermore writes for the Scientific Alliance, which advocates the use of rational scientific knowledge in the development of public policy. To subscribe to his regular newsletter please use this link.


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