Social issues and GM crops
Social issues and GM crops

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Social issues and GM crops

3.2 Communicating Pusztai's findings

In mid-1998, the Rowett Institute released a succession of press releases describing Pusztai's findings. The safety, or otherwise, of GM foods was a hot issue at the time and his preliminary findings gained widespread publicity. Pusztai gave an extended interview to the World in Action TV programme 'Eat up your genes', broadcast in August 1998. He described some of his experiments and outlined his interpretations in ways that helped shape the general tone of the programme, which was highly sceptical about the safety of GM foods in general.

The descriptions of Pusztai's work in the early Rowett press releases were far from clear or consistent, and some of the early claims made were later withdrawn. It was unclear who was responsible for these releases; soon Rowett were sufficiently embarrassed to pronounce that it 'regretted the release of misleading information about issues of such importance to the public and the scientific community'.

Pusztai was suspended from the Institute, in an atmosphere of increasing bitterness and recrimination. It was alleged that the Institute's management came under direct pressure from senior Government ministers to silence Pusztai.

What's especially important to note is that at this time, none of the key data from Pusztai's experiments had been submitted for publication. The work had not been 'peer reviewed' as a means of testifying to the quality of the experiments and the appropriateness of the conclusions. The Rowett then established a four-person audit committee to look at Pusztai's work and they drew the conclusion (posted on the Institute's website - click here to see an overview of the report) that 'the existing data do not support any suggestion that the consumption by rats of transgenic potatoes expressing GNA has any effect on growth, organ development or immune function'. Pusztai disputed the findings of the audit committee, but they were disinclined to modify their findings in the light of his objections.

Such developments helped fuel the significant amount of press coverage that took place at the time (late 1998), much of it raising doubts about the safety of GM food and expressing a good deal of sympathy for Pusztai, whom many thought had been shabbily treated. Much of the information that fuelled the dispute was available on the Web, including Pusztai's own more detailed account of his experimental design and conclusions, in his 'Alternative Report' (also available on the Rowett Institute's website).

Pusztai's findings attracted some support from fellow scientists, in particular 20 individuals from 14 countries produced a widely distributed memorandum. But the majority of the other opinions expressed were hostile, focusing on concerns about the rats' inadequate diets, whether appropriate control experiments had been run, the number of rats used in each group and the appropriateness of the statistical tests that had been applied to assess the significance of the data - concerns that Pusztai and his co-author attempted to answer, though not in a way that satisfied critics.

In June 1999, the UK's premier scientific body, The Royal Society, published a review of Pusztai's work. The review process involved the assembly of existing information, the elicitation of further information from Pusztai, his co-workers and his critics and the invitation to six referees (intended to be both independent and anonymous, following standard peer-review practice) to critically evaluate the information available. The Royal Society report claimed that the experiments were poorly designed, with little information on how the GM and control diets differ. For example, the Royal Society team felt that lack of information about differences in the chemical composition between strains of GM and non-GM potatoes meant that firm conclusions were difficult. The use of a diet of raw potatoes for feeding rats was questioned, given that potatoes are renowned for containing high levels of natural toxins. They also pointed out that, as far as they could ascertain, Pusztai's measurements were not conducted 'blind'; which should be standard practice.

Question 7

How might such experiments have been conducted 'blind' and what would have been the advantage in doing so?


The scientists performing the measurements - in this instance, measuring body mass or looking for effects on the immune system - should be unaware of (i.e. 'blind to') the particular treatment that any one rat has been subjected to. This is to guard against unconscious bias in the recording and interpretation of results; the risk is that data are recorded in ways that favour expectations.

The Royal Society group concluded that:

The uncertainty and ambiguity of the data urge great caution in the interpretation of the results presented. A much improved experimental design, with stringent controls, would have been needed if the claims made for the study were to be convincing. Even if the results of the particular study had supported the claims that have been made for them, it would have been unwise to use them for making statements about the safety or otherwise of all GM foods.

Pusztai disputed the Royal Society team's findings and expressed strong resentment that he had not been sufficiently involved in drawing up of the Royal Society report. He also emphasised that he and co-workers had

never inferred from the results of the work with GM potatoes that GM foods were harmful to human beings. Indeed, we have never said that GM potatoes were harmful to anything but rats. However, we have to point out that the genetic modification method we used is almost identical to the methods used in most presently marketed GM foods in the UK without any biological testing.

Pusztai's arguments continue as follows:

A great deal has been said about the design of the experiments, which is quite remarkable because no design is described in the reports [..] no diets, methods, analytical techniques, rat ages, methods of feeding and other animal experimentation methods are described but as it has been pointed out on innumerable occasions these were reports (and not scientific papers) compiled for people who were fully aware of all these and not written for peer-reviewing. The implication by the RS report that we had bias in our measurements is highly offensive and therefore fully rejected by us.

The one area where Pusztai and the Royal Society review team seem united is in their recognition of the need for further work and clarification, though they do so from different stances. Pusztai continued to defend the quality of his disputed data claiming that 'the data reliably and convincingly demonstrate that the inclusion of GM potatoes in the rat diet had a number of harmful effects on growth, organ development and immune response'. He claimed that though these were preliminary experiments, they were 'well designed, expertly carried out and subjected to correct statistical analysis'. In Pusztai's view 'the results could serve as the basis for further developments'. But the Royal Society review team thought that:

The only way to clarify the current situation would be to refine the experimental design of the research done to date and to use this as the basis for further studies in which clearly defined hypotheses were tested, focused on the specific differences already claimed. It would be necessary to carry out a large number of extremely complex tests on many different strains of GM and non-GM potatoes. It would be important to ensure that these studies had sufficient statistical power (in the sense that numbers in each experimental group were sufficient to deal with the variability in individual response) to come to a clear conclusion. It would also be important to take adequate account of the age and the susceptibility of the animals and the wholesomeness and adequacy of the entire diet. Careful thought would have to be given to the specific targets for any hypothesised damage.

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