French corn study unique but draws extreme criticism

Sep 28, 2012

A recently-released study from France has found that “RoundUp Ready” genetically modified (GM) corn and RoundUp, when consumed over a long period of time, are extremely carcinogenic. The study is unique for its length, but is receiving significant criticism for its unusual level of complexity and failure to disclose key information regarding the methods of the study and data, among other things.

The study—“Long term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize” as currently appearing in the Food and Chemical Toxicology academic journal—studied a group of 200 rats over two years and their reactions to RoundUp Ready corn and RoundUp itself.

The rats were broken into 10 groups composed of 10 males and 10 females each. One group was the control, fed a diet 33 percent composed of non-GM corn and plain water. Of the remaining nine test groups, three were fed varying levels (11 percent, 22 percent, and 33 percent) of GM corn not treated with RoundUp, three were fed varying levels of GM corn that were treated with RoundUp, and the remaining three groups were given the control group’s non-GM corn but had varying levels of RoundUp added to their water. Results were gauged across the varying test groups and between the sexes.

In the control group, three males (30 percent of male control group) and two females (20 percent of the female control group) died prior to the conclusion of the study. This is in comparison to the 50 percent and 70 percent of the overall male and female test populations, respectively, which died prior to the conclusion of the study.

Female rats most frequently possessed and died from mammary tumors, with the test groups seeing several times more tumors and larger tumors which developed earlier than in the control females. Males, on the other hand, suffered from kidney and liver issues, including tumors and necrosis, once again in greater number, size and early emergence in the test groups than in the control group.

A particularly noteworthy detail is the researchers did not see proportionate effects on the test groups with the increased levels of either GM corn, treated corn, or Round- Up in the water. From this they concluded that even their lowest level of test treatments were sufficient to be damaging.

“The results of the study presented here clearly demonstrate that lower levels of complete agricultural glyphosate herbicide formulations [in this case, RoundUp], at concentrations well below officially-set safety limits, induce severe hormone-dependent mammary, hepatic and kidney disturbances,” read the report’s conclusion.


Despite the relatively novel long-term nature of the study—most studies of this sort reportedly last only 90 days—it is being blasted harshly from a number of sides for a myriad of reasons. Key among these complaints are missing information, un conventional and even inappropriate study protocols, the small size of the sample groups, and the type of rat used in the study.

Monsanto—producer of the treatment items used in the study—understandably had a lot to say about the findings.

“This study does not meet minimum acceptable standards for this type of scientific research, the findings are not supported by the data presented, and the conclusions are not relevant for the purpose of safety assessment.

“Toxicologists and public health experts find fundamental problems with the study design. Critical information about how the research was conducted is absent, and the data presented do not support the author’s interpretations.”

The company’s official response to the findings of the study addressed a plethora of flaws and was entertainingly as long as the published report.

Monsanto was not the only one to criticize the study. Numerous academic and professional scientists responded with less than glowing comments on the quality of the study.

“In my opinion, the methods, stats and reporting of results are all well below the standard I would expect in a rigorous study—to be honest I am surprised it was accepted for publication,” said professor David Spiegelhalter, Winton Professor of the Public Understanding Of Risk at the University of Cambridge.

Another UK academic, Tom Sanders, head of the Nutritional Sciences Research Division at King’s College London, commented, “The statistical methods are unconventional, there is no clearly defined data analysis plan and probabilities are not adjusted for multiple comparisons.”

The issue of the sample size has been brought up frequently by detractors. Though 200 individuals used in the test may sound like a lot, having only 20 individuals per test group (or 10 individuals if one further divides the test groups by the sexes) is an almost unheard of low level for scientific studies, particularly of this sort when studied via a rodent model. In its response, Monsanto points out that the sample sizes recommended by the Organization for Economic Co-operation and Development (OECD)—which the study purports to have exceeded—are far larger than those used in the study.

“Despite author’s reference to OECD Testing Guidelines, the study design does not meet OECD standard for number of animals in a chronic study design (50 per group).”

Under these guidelines, the study would have had to use at least 1,000 rats if each treatment group ignored sex as a feature, or as many as 2,000 rats if sex was considered a relevant group unto itself separate from treatment as the study suggests it is.

Several UK and European academics and scientists as well as Monsanto also questioned the study’s results which run contrary to the laudably large body of existing research on the topic.

Monsanto acknowledged the value of the long-term nature of the study but brought up issues with its findings regarding tumor growth in the rats compared to earlier findings with GM corn and RoundUp.

“Multiple lifetime cancer studies from multiple glyphosate registrants, performed independently over the past 35 years have demonstrated that glyphosate does not cause tumors/cancer in rodent species. … “While we concede that a 90-day study is not the same as a lifetime study in purpose or interpretation, the authors of this paper suggest that palpable tumors are occurring as early as four months into the protocol. As tumors take considerable time to grow to palpable size, and as only a minority of tumors generally grow to large size, tumors (even if not palpable) should have been evident in the 90 day studies performed with NK-603 [the version of GM corn used in the study]. This was not observed.”

An Australian professor, Mark Tester at the Australian Centre for Plant Functional Genomics of University of Adelaide, also questioned the disconnect between the French study and the findings of, not only previous studies, but everyday example in a rather humorous way.

“The first thing that leaps to my mind is why has nothing emerged from epidemiological studies in the countries where so much GM has been in the food chain for so long? If the effects are as big as purported, and if the work really is relevant to humans, why aren’t the North Americans dropping like flies?! GM has been in the food chain for over a decade over there— and longevity continues to increase inexorably!” Entertainingly, even Marion Nestle—a vocal food commentator well-known for her strong support for GMO labeling and general anti-conventional agriculture views—found fault with the study. In an opinion piece published on, she pointed out many of the same flaws in the study as Monsanto and the numerous academics cited.

Despite the copious criticisms, the study has had some effect already. Russia has reportedly halted imports of GM corn from the U.S. and has suspended use of Monsanto’s NK-603 corn in the country. French consumer advocacy groups have called for a similar move in their country.

It is too early to tell what if any effect this might have on U.S. corn exports and the general drought-related corn supply issues. Monsanto has said it did not see the study likely to impact its license to export NK-603 corn to Europe after reviewing it.

Though GM corn is not used in the human food supply in Europe, it is used as livestock feed.

In the mainstream media and the so-called “blogosphere,” reports of the study’s findings (absent the criticisms) have been taken up by some as further evidence of the supposed disastrous health effects of GM foodstuffs and herbicides in general. — Kerry Halladay, WLJ Editor