The debate surrounding genetically modified organisms (GMO) is heating up right now, especially with a proposition in California which would require labeling of such foods (I’ll ignore the blatant violation of the Commerce Clause right now).
It is no surprise then that the people supporting such a law would want to bolster their claims for labeling. A study released just a couple days ago did just that. According to the results, rats that were fed a diet high in modified corn and small doses of herbicides grew tumors faster than the rats not being fed this stuff. Immediately press releases and headlines read out: BREAKING NEWS: New Study Links Genetically Engineered Food to Tumors as if this was now a foregone conclusion.
But it hasn’t taken long for the scientific community to summarily reject this study altogether.
The biggest problem with the study is that the groups only consisted of 10 male and 10 female rats — hardly a large enough sample to make any type of statistical determination. Additionally, 80% of this type of rat will normally end up with tumors within 2 years (the length of the study). Scientists also don’t believe rats are a good test subject, since they can’t eat enough corn to actually make a difference.
Other problems with the study included:
• Small sample size
• Maize was minimum 11% of the diet – not balanced
• No non-maize control?
• No results given for non-gm maize
• For nearly 20 years, billions of animals in the EU have been fed soy products produced from genetically modified soybean, mainly from Latin America. No problems have been reported by the hundreds of thousands of farmers, officials, vets and so on.
• The same journal publishes a paper showing no adverse health effects in rats of consuming gm maize (though this is a shorter 90-day study)
• Statistical significance vs relative frequencies.
• We also have to ask why the rats were kept alive for so long – for humane reasons this study would not have been given approval in the UK.
• In Fig.2, I assume the bars with a zero is for the non-maize control. Those bars don’t looks significantly different from the bars indicating 11, 22, and 33% of GM maize in the diet? Have the authors done stats on their data?” (Source: Science Media Center)
Professor Anthony Trewavas, Professor of Cell Biology, at the University of Edinburgh, said:
“The control group is inadequate to make any deduction. Only 10 rodents so far as I can see and some of these develop tumours. Until you know the degree of variation in 90 or 180 (divided into groups of ten) control rodents these results are of no value.
“These figures for normal appearance of tumours in these rodent lines are surely available and using a line which is very susceptible to tumours can easily bias any result. To be frank it looks like random variation to me in a rodent line likely to develop tumours anyway.”
Professor Alan Boobis, Professor of Biochemical Pharmacology, at the Imperial College London, said:
“Some of the effects are presented in a way that makes it difficult to evaluate their significance. For example, there does not appear to be a statistical analysis of the mammary tumours. These occur quite often in untreated animals. One would usually also take into account the historical controls in the testing lab, in reaching a conclusion. The pesticide itself has been subject to long term studies in rodents by others.”
For more quotes and responses to the study from scientists check out the Science Media Center’s press release.
Putting methodology aside, scientists also don’t believe the hype because:
“There’s no apparent reason why that [the results] should be true; No one has found new toxic substances in these crops. And the giant feeding experiment that’s been going on for the past fifteen years — hundreds of millions of Americans consuming GMO ingredients — hasn’t produced evidence of harm, either.” (Source: As Scientists Question New Rat Study, GMO Debate Rages On)
Not only was the study completely non-scientific (thus, not really a study at all), it was conducted by the leader of CRIIGEN, an anti-GMO lobbying group. Whenever a lobbyist is trying to do science experiments, you know they have an agenda. You also know the results are going to support that agenda.
File this under another example of environmentalists trying to scare people into supporting their position and, in this case, a specific ballot proposal. But the scare tactics need to stop and it’s up to the farming community to start letting the truth be known.
UPDATE: I was vindicated because over a year after I published this article, the “study” was retracted from Nature Journal. Read about the retraction and drama surrounding it here.