A peer-reviewed study, authored by Australian scientists from the Institute of Health and Environmental Research has shown pigs fed on a diet of genetically modified grains developed inflamed stomachs at a much higher rate than those fed on conventional grains.

IHER is a research institute in Adelaide, which says it has "a scientific interest in the safety of genetically modified (GM) organisms". Working with colleagues from the United States, including veterinarians and an Iowa pig farmer, the IHER researchers fed 84 pigs on a diet of feed containing GM maize and soy, while a well-matched control group of 84 other pigs ate the equivalent non-GM diet.

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Both groups' feed was sourced from regular commercial suppliers. The GM group's feed contained three separate GM crop varieties. After five months (the length of a pig's commercial lifespan) the pigs were slaughtered and autopsied. Vets carrying out the autopsies were not aware which pigs had been fed the GM diet and which were from the control group.

The study is one of the first to have been carried out on a commercial farm. The researchers said that collecting results 'in the field' provided extra ecological validity to their trial.

Results show severe inflammation

Overall, pigs fed on GM maize and soy were found to be 2.6 times more likely to develop inflammation of the stomach, however the results varied between sexes.  Inflammation in GM-fed males was 4 times more common than amongst the control pigs, whereas females fed on the GM diet were 2.2 times as likely to suffer severe inflammation of the stomach.

Females also suffered other effects, the researchers said; uteri of pigs fed on GM were 25 percent heavier on average than those fed on the GM-free diet. Dr Judy Carman, the study's lead author said, "Because male pigs were neutered at 3 days of age in order to provide meat free of boar-taint, we were only able to look at the female reproductive system in these pigs."

The study was published this week in the Journal of Organic Systems. The authors said that their findings highlight a gap in current GM risk assessments; they said that no consideration has so far been given to the combinatory effects of GM crops.

Dr Carman, director of IHER and an associate professor at Flinders University in Adelaide, explained, "Regulators do not require animal feeding studies on mixtures of GM genes and their proteins, regardless of whether the genes are all 'stacked' into the one plant or spread across several plants that are eaten in the same meal. We chose pigs because they have a similar digestive system to humans, and because some of the investigators had been observing reproductive and digestive problems in pigs fed GM crops."

The seeds in question had been altered, as is the case with almost all GM seeds currently on the market, to resist applications of herbicide or to produce toxins designed to kill insect pests. Although the biotech industry and its supporters maintain the crops are safe and suggest "hundreds of [scientific] studies" back their stance, there are still scientists who believe that the modification process, which remains relatively crude, has given rise to novel proteins which could have unintended effects.

Last year, a French professor from Caen University conducted a feeding study on rats in a laboratory, which found the rats developed tumours at a much higher rate when fed GM maize. However, the study was widely criticised upon its release and the European Food Safety Authority declared it to be "inadmissible" as evidence of health effects related to consumption of GM crops, following a review.

Reaction to Australian GM study

The IHER study caused a furore upon its release this week, with industry groups and supporters of the controversial technology rushing to discredit the authors. Critics have pointed out that the study appeared in a minor journal, with a pro-organic farming stance. They suggest that the study was funded by GM-sceptic organisations, though the authors claim research was part-funded by the Australian government, which currently supports GM technology.

Pro-GM activist and author Mark Lynas was one of the first to respond to the study. He too highlighted the anti-GM stance of a number of its major contributors and backers. He also pointed out that pigs fed on the non-GM diet were shown to be twice as likely to develop liver problems, but suggested "negative results were not what Carman et al were looking for".

Lynas claimed that incidences of 'mild' and 'moderate' inflammation in the stomachs of non-GM animals outweighed cases in animals raised on the GM diet, and suggested that, although 'severe' inflammation was far more common in the GM group, "You can immediately see how the data is all over the place… It's clearly just chance, and all the pigs are not doing well and suffering stomach problems."

Dr Carman said in response to Lynas' accusations that, "There were 38 people in the acknowledgement section, including an ex government Minister, an ex Chief of Staff to the Govt Minister and an ex member of the Board of Australia's food regulator, as well as numerous scientists with more qualifications than Mr. Lynas has… and numerous farmers who were involved in the research."

She continued, "Mr. Lynas either did not read the paper well enough or saw the analyses but did not understand them. The level of inflammation in the non-GM fed group was concentrated in the mild to moderate range of inflammation. Feeding GM crops boosted that to severe inflammation, and this was a significant finding."

Dr Carman concluded, "Our findings are noteworthy for several reasons. First, we found these results in real on-farm conditions, not in a laboratory, but with the added benefit of strict scientific controls that are not normally present on farms. Our results provide clear evidence that regulators need to safety assess GM crops containing mixtures of GM genes, regardless of whether those genes occur in the one GM plant or in a mixture."

Also commenting on the study, Professor Thomas Lumley of the University of Auckland, who is not affiliated with the researchers, said "This study is much better designed and analysed than the controversial French GM/glyphosate study from last year." He recommended, "The study should not change policy on its own, but it is worth taking seriously for future research."

However, Prof Lumley cautioned, "The results provide only modest evidence of harm, even for pigs on a 100 percent GM diet, because many possible effects were tested, making it quite possible that some difference would turn up just by chance."

By contrast, Prof Tom Sanders of Kings College London slated the IHER study. He said, "It does not look like a convincing adverse effect as it was a minor incidental finding."

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