ngin - Norfolk Genetic Information Network

Prof Trewavas requires a health warning

Prof Trewavas requires a health warning

Prof Anthony Trewavas is often the expert of choice whenever a critical perspective on organic food and farming is required by the UK's media. From the media's perspective Trewavas presents as a prominent scientist who has written extensively on organic farming, including two articles in the prestigious science journal Nature. However, Trewavas is also a scientist with a history of propagandising on behalf of GM foods and against organic farming and there is more than ample evidence that in the course of that crusade he has put into circulation many statements which are both extreme and unsupported.

In October 2001 "Professor Trewavas,  Professor of Plant Biochemistry at the University of Edinburgh" was named in the High Court in London as the source of a letter making libellous allegations against Lord Melchett and Greenpeace in relation to organic farming and GM foods. [Greenpeace wins damages over professor's 'unfounded' allegations - Education Guardian, Monday October 8, 2001]

A published apology in the Scottish newspaper, the Herald, on the 6th October confirmed that, "On 3 November 2000 the Herald published a letter it had received from Anthony Trewavas." The conclusion of the libel case led to critical comment on the fact that Prof Trewavas was not only a leading Fellow of the Royal Society but is even listed in the Society's media directory as an expert available to help journalists get their science stories right. [see: The Ecologist vol 31 no. 10 p.11, ISIS News, Institute of Science in Society, Private Eye 1040, p.4]

In response to this adverse publicity, Prof Trewavas, in letters to the Herald and others, has sought to deny responsibility for the libel letter published under his name. However, Trewavas has admitted to encouraging others to circulate the material in question as widely as possible, and to sending the material to, amongst others, a newspaper editor and a PR operative with this intent. More recently it has emerged that the original author of the material that Trewavas circulated was another PR operative involved in a Monsanto dirty tricks campaign.

The libel case is, in fact, only the latest controversy centering on Prof Trewavas and his views and activities. Take, for instance, the advice he gave to US scientists on a listserv supporting GM foods in April 2000, where he describes critics of genetic engineering as, "bloody minded, anarchist and frankly merely destructive." According to Trewavas, opponents of the technology are interested solely "in destroying US agribusiness". In the same message Trewavas describes the international environmental group Greenpeace as "controlled by extremists/nihilists and other subversives... whose only interests [sic] is in destroying business/damaging trade and who have no solution to world population problems except to let people die." He also advises enlisting the help of far right US congressmen like Jesse Helms by alerting them, "that a subversive organisation directed from europe is attempting to destroy US agriculture and US farming."  [advice to US scientists from: "Tony Trewavas" <>]

In the same piece Trewavas advises GM supporters to take every opportunity to contact the media to attack the critics and put forward pro-GM views and Prof Trewavas certainly cannot be faulted for failing to take his own advice! As part of his tireless crusade, Trewavas has even had two articles attacking organic farming published in the journal Nature. However, both are simply opinion pieces involving no original research and the arguments he presents and the sources he draws upon are open to very serious question.

The second of the two Nature pieces is taken apart in the article below by Angela Ryan.  The inadequacy of Trewavas' scholarship is equally apparent in the first, 'Much Food, Many Problems' [Nature 402, 231 (1999)]. Here, for example, he presents his readers with a litany of alarming claims:

"Going organic worldwide, as Greenpeace wants, would destroy even more wilderness, much of it of marginal agricultural quality15."

"Mycotoxin contamination [of organics] , and infection from the potentially lethal Escherichia coli O157, are additional problems15."

"average crop yields [for organics] on a variety of soils are about half those of intensive farming15-17"

The reference given by Trewavas for all three points is, "15. Avery, D. in Fearing Food. Risk, Health and Environment (eds Morris, J. & Bate, R.) 3-18
(Butterworth-Heinemann, Oxford, 1999)". Anyone who actually follows up this reference discovers that it's to a piece by the controversial US journalist and commentator, Dennis Avery - author of the book, 'Saving the planet with pesticides and plastics' - who just happens to (a) work for the biotech-industry-funded Hudson Institute and (b) have no credible scientific credentials. What's more, all Avery's highly partisan claims about organic agriculture in 'Fearing Food. Risk, Health and Environment' lack any specific references to supporting evidence! In other words, Trewavas' trail of evidence for this series of damaging claims leads nowhere but to the assertions of a highly dubious commentator.

Indeed, the article by Avery to which Trewavas repeatedly refers appears in a book edited by two notorious pro-industry propagandists connected to a corporate front funded by Big Tobacco! Nor is this Trewavas' only connection to the book's editors, Morris and Bate, and their pro-corporate propaganda. In early 2000 Trewavas appeared as a witness against organic farming in the Counterblast TV programme put together and presented by Roger Bate in his role as Director of the tobacco-industry funded European Science and Environment Forum.

Needless to say, Prof Trewavas is not entirely disinterested in his simultaneous promotion of GM crops and crusade against organic farming. Trewavas is himself a GM crop researcher. He also serves on the Governing Council of the John Innes Centre, a plant biotech institute which has itself been mired in controversy over its pro-GM propagandising.

So while Trewavas issues lurid warnings about organic farms acting as "repositories of disease", in reality it is Prof Trewavas himself who is in real need of a health warning!

ISIS News No 11/12 October 2001,
Institute of Science in Society, 

Prominent scientists have been denigrating organic agriculture recently on both sides of the Atlantic. This debate has even reached the pages of
the top science journals. Angela Ryan reviews and rebuts the arguments put forward.

Sir John Krebs, Head of the UK Food Standards Agency (FSA) said, "in my opinion and in the opinion of the FSA, consumers who buy organic produce
are not getting value for money if they think they're buying food with extra nutritional quality or extra safety"[1].

Soon afterwards, as if on cue, an article appeared in Nature entitled, Urban Myths of Organic Agriculture, by Anthony Trewavas, Prof. of Plant
Biochemistry, Edinburgh University. It sets out to refute a common argument "that organic farming is ‘holistic’ and superior to reductionist ‘chemical’ agriculture".

This dichotomy is false, and "neither is superior". He claims "there is very little science to organic farming" [2].

Organic agriculture bans the use of synthetic pesticides, herbicides, fertilizers, fungicides, veterinary drugs (antibiotics, growth hormones), synthetic preservatives and additives, and irradiation, many of which are associated with harmful effects on health and biodiversity. Not only that, a United Nations Food and Agricultural Organisation (FAO) 1998 report on organic farming suggests con-siderations like ethical values and sustainable production principles are gaining weight in the food sector as "integral product values" for consumers [3].

The former UK Ministry of Agriculture Fisheries and Food (MAFF) 1998 Review examined comparative studies on biodiversity, and concluded,
"organic regimes have the greatest benefit for biodiversity at the farm level".

But according to Trewavas, organic farming practices do not "necessarily conserve the environment". He claims that "current synthetic pesticides
are very unstable; only transient declines of most field insects are reported even at full pesticide dosage". And conjectures, "lower levels of aphids observed on organic farms could well reflect lower nitrogen and protein content of organic crops".

A new study comparing arthropod communities and pest damage levels to fresh market tomato, Lycopersicon esculentum, was carried out on 18
commercial farms in California, representing a range of management practices, half operating as organic and half as conventional [4].

The study found that insect pest damage varied across the spectrum of farm management practices and organic and conventional farms did not
differ significantly for any type of damage to tomato foliage or fruit.

However, there was a significant difference between the actual community structures of arthropods. There was higher abundance of natural enemies,
and greater species richness of herbivores, predators, parasitoids and others in organic farms where arthropod biodiversity was one-third

Trewavas claims "developments in the past 25 years have shown how conventional agriculture can be much more sustainable and environmentally friendly than organic farming". He cites the Institute of Arable Crops Research (IACR) website as reference.

The scientific literature contradicts his claim. A new study in Nature compared the sustainability of organic, conventional and integrated apple production systems in Washington State from 1994 to 1999 and found the organic systems ranked first for environmental and economic sustainability, with the integrated second, and the conventional last[5].

The researchers measured soil quality, horticultural performance, orchard profitability, environmental quality and energy efficiency, which are all specific indicators of sustainability.

They found that all three systems gave similar apple yields. The organic and integrated systems showed higher soil quality and lower negative
environmental impact. But the organic systems produced sweeter and less tart apples, higher profitability and were more energy efficient. Tree
growth was similar for all three systems but analysis of fruit firmness at harvest and after storage showed that the organic fruit was firmer.

Environmental impacts were assessed using the rating index employed by scientists and growers. The total environmental impact rating of the
conventional system was 6.2 times higher than that of the organic system, and the integrated system was 4.7 times higher.

Energy accounting was divided into inputs (labour, fuel, fertilisers and so on), output (yield) and output/input ratios (energy efficiency).
Energy efficiency for the organic system was 7% greater than the conventional system and 5% greater than the integrated system.

Enterprise budgets were generated each year to calculate net returns from total costs and gross receipts. There was no price premium for integrated fruit but the price premium of organic apples averaged 50% higher than conventional prices. Hence, the organic system was more profitable.

The use of manure on organic farms results in higher, beneficial levels of biodiversity, especially earthworms, but Trewavas claims there are "numerous problems", including "possible effects on human health".

Manure is also widely used on conventional farms. Faecal matter is known to contain a range of human pathogens but properly treated manure is effective and safe. Furthermore, unlike conventional regimes, mandatory organic certification bodies inspect farms to ensure standards are being met.

Trewavas states, "ploughing in of legume crops on organic farms to improve soil fertility and continued manure breakdown leads to nitrate leaching into aquifers and waterways at identical rates to conventional farms".

The occurrence of nitrates is a major public health hazard as they can be converted to nitrosamines, which are carcinogens and nitrates impair the ability of blood to carry oxygen.

But FAO reports that nitrate content on organic farms is "significantly lower" due to absence of soluble fertilizers and the governments of Germany and France encourage conversion to organic farming in a bid to improve water quality in certain areas.

Furthermore, the use of ‘biosolids’ from wastewater treatment facilities (sludge) on conventional farms raises concern over heavy metals, toxic organic compounds, such as dioxin, PCBs and persistent microbial pathogen contamination. The Codex and EU organic standards prohibit the use of sewage sludge and the US National Organic Programme also bans it.

Organic regulations recommend hay for animal feeding, but Trewavas claims "hay-fed animals infected with Escherichia coli 0157 incubate
this dangerous organism longer than conventional animals fed with grain".

FAO report that the US Centres for Disease Control (CDC) identifies the main source of E. coli infection as meat contaminated during slaughter.
Virulent strains of E. coli such as 0157, develop in the digestive tract of cattle that are fed mainly with starchy grain [6]. Cows fed with hay generate less than 1% of E.coli found in faeces of grain-fed animals. FAO concludes, "ruminants like cattle and sheep fed in the organic system reduce the risk of E. coli infection".

Trewavas writes, "food mycotoxins from contaminating fungi definitely contribute to European cancer rates, and fumonisin and patulin are both
reported to be higher in organic products". He claims "failure to use effective fungicides on organic farms has led to these farms acting as repositories of disease" and "organic farms may be protected from the full effects of disease outbreak because they are surrounded by conventional farms using proper fungicides."

Mycotoxins are toxic by-products of certain moulds that can grow on food. Since fungicides are not allowed in organic systems, many studies have investigated their presence in both organic and conventional foods [7]. From these, FAO conclude, "it cannot be concluded organic farming leads to an increased risk of mycotoxin contamination".

FAO report two studies that found aflatoxin levels in organic milk were lower than conventional, suggesting additional risks involved with feeding mainly grain to conventionally raised livestock. Aflatoxins are most toxic and can induce liver cancer at low doses if ingested over time. The report states, "as organically raised livestock are fed higher proportions of hay, grass and silage there is a reduced opportunity for mycotoxin contamination."

Several other hazards are associated with conventional food production. In Central and Eastern Europe, there are areas of high contamination due
to industrial activities, from mining, smelting, the energy sector, agricultural practices and disposal of hazardous and municipal wastes.

FAO reports, "A more widespread use of organic agriculture would contribute to a reduction of environmental degradation, ultimately resulting in reduced levels of contaminants in food". Furthermore, "EU member states increasingly see organic agriculture as a tool for improving rural economies and stability, while simultaneously increasing biodiversity and environmental sustainability".

It is clear that holistic approaches that link ecology and economics benefit both the ecosystem and human health, and are competitive in commercial markets.

[1]Urban Myths of Organic Farming, by Anthony Trewavas, Nature, Vol 410, 22 March 2001 pp 409-410

[2]'Nutritionists question study of organic food', Nature, Vol 412, 16th August 2001

[3]Twenty Second FAO Regional Conference for Europe, Porto, Portugal, 24-28 July 2000, Agenda Item 10.1, Food Safety and Quality as Affected
by Organic Farming, Available for download at

[4]D.K. Letourneau & B Goldstein (2001) Pest damage and arthropod community structure in organic vs. conventional tomato production in
California, Journal of Applied Ecology, vol 38, pp 557-570

[5]John P Reganold, Jerry D Glover, Preston K Andrews and Herbert R Hinman (2001), Sustainability of three apple production systems, Nature,
Vol 410, 19th April, pp 926- 930

[6]Couzin, J et al (1998) Cattle Diet Linked to Bacterial Growth, Science Vol 281, pp1578-1579

[7]Marx H, Gedek,B & Kallarczil, B (995) Comparative investigation of mycotoxicological status of alternative and conventional grown crops, Z
Lebensm Unters Forsch, 20, 83-6