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Genetically modified corn and cancer – what does the evidence really say?

French scientist Gilles-Eric Seralini caused quite a stir last week when he claimed he’d shown cancer in rats increased when they were fed genetically modified corn and/or water spiked with the herbicide…

The French paper linking GM corn and cancer in rats should have been rejected on a number of grounds. Vermario

French scientist Gilles-Eric Seralini caused quite a stir last week when he claimed he’d shown cancer in rats increased when they were fed genetically modified corn and/or water spiked with the herbicide Roundup. The paper, which seven of his colleagues co-authored, was published in the peer-reviewed journal Food and Chemical Toxicology.

France’s ministers for agriculture, ecology and health responded swiftly by commissioning the National Agency for Health and Safety to look into the claims. Depending on the findings, they could invoke an emergency suspension of imports of the Monsanto GM maize strain NK603, used in the study, into Europe. Now that’s what I call high impact.

But how did the authors come to their conclusion? And can such a significant claim be made using the study data?

Rat selection

The study focuses on cancers in rats. For this they use the Harlan Sprague-Dawley strain of rat, which is known to be predisposed to getting cancer. Lots of them. Over 70% of males and 87% of females from this strain reportedly get cancer during their lifetime, whether they have been fed GM corn or not. So it shouldn’t be a surprise that so many of Seralini’s rats were found with cancer.

To make sense of this study you have to ask the simple question: “does feeding rats GM corn and/or Roundup increase the frequency of cancers compared with rats that have been given non-GM food?”

To do this, the authors of the study split up 200 rats into ten groups. One “control” group (ten male and ten female) were fed non-GM corn and had access to plain water. The researchers monitored for the development of cancer over a period of two years.

Nine other groups of twenty rats (ten male and ten female) were also monitored, but this time, these groups were given food containing 11%, 22% or 33% of NK603 GM corn, 11%, 22% or 33% of NK603 GM corn treated with Roundup*, or just had Roundup spiked in their drinking water at different concentrations.

The male and female rats in the control group lived for just under two years. Other studies identified that these rats die from cancer or kidney failure around this time. But the authors don’t mention this. They simply write:

“ After mean survival time had elapsed, any deaths that occurred were considered to be largely due to aging.”

They have effectively chosen not look at – and therefore don’t have to report on – why rats in the control group died. This assumption alone is sufficient grounds for rejecting this paper from publication.

Treatment group vs the control

In the study, Figure 1 (view here) shows Kaplan Meier plots the number of rat deaths by “control group” and other “treatment groups”.

What do these mean? Well, not much because the authors failed to use a statistical test to tell if there was a difference between the control groups and treatment groups.

This is important, as all their claims relate to the incidence of cancers (and other “diseases”) in the “treatment group” compared to the “control group”. These comparisons can only be made if a statistical test shows that what you observe is not happening by chance.

The Harlan Sprague-Dawley strain of rat is predisposed to getting cancer. jepoirrier

Overstating the evidence

Still on Figure 1, we see that several “treatment groups” of male rats receiving GM NK603 corn (the 22% group and 33% group) actually had fewer cancers than the male control group at their arbitrarily determined point of assessment.

Similarly, a treatment group of male rats receiving 33% GM corn and Roundup had no difference to the control group, and two treatment groups receiving Roundup (A and C) had the same or less incidence of cancer compared with the control group.

By their perverted logic, they could equally claim that for male rats:

a) high percentages of GM corn (22% and 33%) was “protective” against getting cancer compared to group of control male rats

b) having 33% of GM corn with Roundup showed no difference to the control group and therefore wasn’t harmful to male rats, and

c) using 0.5% Roundup in the drinking water was protective against cancer in male rats compared to the the male control group.

But you can’t. You can no more make these statements than the claims about the increased incidence of cancers in the female rats in the various treatment groups. No statements can be made because no statistical test has been applied.

The full picture

One sentence that should set alarm bells ringing is the claim that “All data cannot be shown in one report.”

The retort to that statement is, “Oh yes it can. Please show it to me”. If you are reporting data, you need to show all the data.

Not enough space? Put it in the supplemental data.

In the data section, the authors show examples of pathology, histology and electron microscopy images of affected organs in the treatment groups and mention results from genetic testing of samples. All well and good, but for the genetic tests, they don’t show any data other than a statement of claim.

They also don’t present any biochemical data from the male rats – half of all their studied rats. In the legend for table 3 (which shows the “Percentage variation of parameters indicating kidney failures of female animals), they claim "Male kidney pathologies are already illustrated in Table 2” (which shows a “Summary of the most frequent anatomical pathologies observed”). But we’re not shown the raw, unmanipulated data, tested with standard statistical tests, for males and females.

Nonsensical statements

The authors then go on to describe the cancers in detail. They state:

“ Up to 14 months, no animals in the control groups showed any signs of tumors whilst 10–30% of treated females per group developed tumors, with the exception of one group (33% GMO + R).”

Well done. They have just created a non-predefined outcome measure and made a biologically nonsensical statement.

Do they mean to imply that female rats eating the highest percentage of GM corn with Roundup are mysteriously no more affected than the female control group, compared to other female “treatment groups” which were somehow more affected?

Once again, no statistical test is applied and no conclusions can be drawn.

Further, they don’t describe diseases affecting the “control group”. At all. By neglecting to state if there were any changes in the “control group”, you cannot make any statement about the “treatment groups”. That’s why you have controls.

So, what have we learnt?

This study has shown that old Harlan Sprague-Dawley rats get cancers and other diseases. This has been shown before.

What this study does not show is that exposing these rats to GM corn and/or Roundup makes any difference to the frequency of cancers or other diseases. It can’t because no statistical tests have been applied, and perhaps most worryingly, the authors do not comprehensively report on why rats in the control group died.

This study can hardly be the basis from which any government should make policy decisions or draw conclusions about the safety of the NK603 GM maize or Roundup.

Read an article about the murky release of the paper – Modifying the message: how tricks masked home truths about anti-GM science

*A previous version of this article incorrectly stated this group had Roundup spiked in their drinking water at different concentrations.

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  1. rory robertson

    logged in via email @gmail.com

    Good morning, Ashley. You have highlighted what seem to be some real problems with that paper, and good on you. I encourage you to work hard to ensure the proper authorities become fully aware of the key facts of the matter.

    Like you, I have concerns about a "peer reviewed" scientific paper that in my opinion should be corrected or retracted. In terms of "Overstating the evidence", is the "Long term toxicity of a Roundup herbicide...." paper any worse than the University of Sydney's high-profile…

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  2. Laurie Willberg

    Journalist

    "the authors failed to use a statistical test to tell if there was a difference between the control groups and treatment groups."
    So before eating GMO products make sure you have a "statistical test" to determine whether you are in the group likely to get cancer or not... Kindly let us know when such a test is available, however it's highly unlikely anyone would bother.
    There is enough data to provide any prudent person with sufficient evidence to scrupulously avoid GMO products. Consumers have a right to know what they're eating, hence the movement in California to make food labelling mandatory.
    GMO crops have consistently been shown to actually have lower yields, have resulted in the creation of super weeds, contaminate the soil, destroy beneficial soil bacteria, and routine pesticide spray drift causes cancer in nearby communities.
    GMO is a blight on humanity. The French research is a wake-up call.
    Watch the CBC documentary "The World According to Monsanto".|

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    1. David Tribe

      Senior Lecturer in Food Biotechnology and Microbiology, Agriculture and Food Systems at University of Melbourne

      In reply to Laurie Willberg

      This current article is not about crop yields so Ill be brief. Your claim about yields are wrong.

      In Indian cotton the boost to yielld is dramatic.

      http://gmopundit.blogspot.com.au/2012/07/economic-impacts-and-impact-dynamics-of.html

      http://gmopundit.blogspot.com.au/2012/04/measuring-contribution-of-bt-cotton.html

      The new GM drought resistant corn in USA is holding up well, and corn rootworm protected corm uses water more efficiently so performs better in terms of yield under stress

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    1. Ashley Ng

      Post Doctoral Fellow and Haematologist at Walter and Eliza Hall Institute

      In reply to Chris Booker

      Hi Chris.

      I would contend that I did not leave out the relative risk between groups ~ that was the flaw on the part of the authors. The authors had effectively chosen not look at – and therefore don’t have to report on – why rats in the control group died after an arbitrary time point. All the deaths they state was due to ageing, rather than report the incidence of cancers or other diseases in the control group beyond this time. No relative risks could therefore be determined.

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    2. Chris Booker

      Research scientist

      In reply to Ashley Ng

      Sorry probably my poor use of English - I meant how could the authors leave out relative risks, not you personally! Thanks for the reply.

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    1. rory robertson

      logged in via email @gmail.com

      In reply to Ashley Ng

      Ashley, like me you are new to the wise ways of modern science. Silly us, but it turns out that the "peer review process" is no guarantee of quality. In the case of the high-profile "Australian Paradox" paper, the peer-review process was either non-existent, incompetent or ignored. The lack of genuine quality control seems to be a particular issue with pay-as-you-publish "journals", especially when the lead author and the "Guest Editor" turn out to be the same person! http://www.australianparadox.com/pdf/Sept2012-Conversations.pdf

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    2. Bob Phelps

      Director at Gene Ethics

      In reply to Will Hardy

      Will sensibly asks why there are no similarly critical reviews by 'independent' boffins of the trashy, unpublished and often commercial-in-confidence swill submitted to our regulators in applications for GM crop and food licences.

      Food Standards Australia NZ claims there are such critical reviews - its own assessments of the applications, not one of which FSANZ has ever modified or rejected. Almost 60 varieties of eight GM crops are approved in Food Standard 1.5.2 but just one provisionally requires…

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    3. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to Bob Phelps

      Bob, Will didn’t ask that question at all, but I see you want to provide a comment anyway.

      It might help if you did some research on how FSANZ assesses GM foods before commenting. I recommend http://www.foodstandards.gov.au/consumerinformation/gmfoods/ as a place to start. For labelling http://www.foodstandards.gov.au/consumerinformation/gmfoods/gmlabelling.cfm . There you will find “GM foods, ingredients, additives, or processing aids which contain novel DNA or protein that has come from an approved GM food must be labelled with the words ‘genetically modified’” provided the ingredient is present above 1%.

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    4. Bob Phelps

      Director at Gene Ethics

      In reply to Christopher Preston

      Those so-called consumer information sheets are a brief and misleading account of how GM food labelling really stands. For what is enforced, instead see the law - Standard 1.5.2 here: http://www.comlaw.gov.au/Details/F2012C00354 The Schedule in Standard 1.5.2 shows only 1 of the 61 approved varieties of genetically manipulated canola, corn, cotton, lucerne, potato, rice, soybean and sugarbeet requires any GM labelling. FSANZ assumes that all DNA and protein is removed from the other varieties by all processing technologies and therefore requires no labels.

      There is no scientific or practical basis for that assumption but FSANZ does no testing. When independent tests have found GM in unlabelled processed food products FSANZ has forgiven the transgression under the 'adventitious presence' provisions of the Standard, even when repeat tests found GM in samples of the same products taken and tested later.

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    5. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to Bob Phelps

      Bob, you are being deliberately misleading here.

      Labelling is required where material containing novel DNA or protein is present in products at greater than 1%. There are some other requirements for things like processing enzymes that I will pass on for the moment, but the interested reader can find the information at the fact sheets. What FSANZ does not require is labelling where the product is so highly refined that it will contain no intact protein or gene, such as with oils and sugars.

      Most of the human consumption from soybeans canola and cotton comes in the form of oil. Hence no labelling is required. Where meal from these grains or from corn included in food at more than 1% they would require labelling. For example, the donuts at my local supermarket have a proud label stating the GM ingredients are included.

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    6. mark mc dougall

      educator

      In reply to Christopher Preston

      It is a wonder that you find such fault with this study, which is the first of its kind and is more detailed than any of the studies that were used to approve 603.
      It is criminal that the patent owns the profit but we own the risk, courtesy of government approval with tests that are likely to be revealed far more compromised than this.
      Asbestos was a battle of shoot and howl down the messenger, as was tobacco, and ssri-suicide links for the young and mass murder links for adults(columbine,aurora etal),... but times change,..and people and corporations should be liable.

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    7. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to mark mc dougall

      Mark, I find fault with the study because it is poor science. The authors of the study have deliberately withheld from their readers the information that between 70 and 85% of the rats they used will get tumours from eating normal rat chow over a 2 year period. They also claim to have followed the OECD guideline 453. This claim is incorrect. They have used the wrong statistical tests, they don't have enough statistical power in their experiments, they have cherry-picked results and their conclusions are not supported by the results shown. In addition to all this, the results are shown in an overly-complicated manner that hides their real significance.

      How could I not criticise the work?

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    1. mark mc dougall

      educator

      In reply to Michael Lardelli

      And make it multi generational- there is a lot of anecdotal stuff about farm animals suffering decreased fertility and fetal mortality

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  3. Paul Rogers

    logged in via Twitter

    I can't see a problem with Sprague-Dawley rats in experimental cancer research. They've been used for decades in testing for all sorts of carcinogens by the US Cancer Institute scientists and others at NIEHS as well as many others external to these units.

    In this presentation from Ramazzini Institute, you can see the comparison between SD rats and human cancer (slides 13-16). http://bit.ly/QsDRno

    Your other criticisms may be well founded, but this old furphy is a cornerstone of spurious industrial criticism of environmental cancer testing, and it degrades your article.

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    1. Ashley Ng

      Post Doctoral Fellow and Haematologist at Walter and Eliza Hall Institute

      In reply to Paul Rogers

      Hi Paul.

      My major criticisms of the study were with the methodology, inadequate and inappropriate reporting of outcomes of the control group and paucity of statistical analysis ~ not the strain of rat they used.

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    2. Paul Rogers

      logged in via Twitter

      In reply to Ashley Ng

      Ashley, fair enough.

      I do consider your other points useful, and I have not yet seen any detailed defense by the authors, in any forum, that would reinvigorate their position.

      However, other groups have addressed criticisms similar to yours, ie GMWatch: http://tinyurl.com/8dszj69

      It will be interesting to see how it pans out over time. Thanks.

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    3. David Tribe

      Senior Lecturer in Food Biotechnology and Microbiology, Agriculture and Food Systems at University of Melbourne

      In reply to Paul Rogers

      Paul
      The Ramazzini Institute slides you show are very interesting and a great contribution to this discussion.
      I fully agree with you that it is possible to use SD rats to evaluate carcinogenicity. But to do this you need large numbers of animals and do a full analysis of data.

      Its interesting that although this Ramazzini group criticise OECD standards for long term tests (which require 50 animals per test group), Ramazzini also use large numbers of animals (eg 90 per treatment ) in their tests, and even use larger numbers of the control animals to assure more power when making multiple comparisons

      see

      http://www.ncbi.nlm.nih.gov/pubmed/17119234
      http://www.ncbi.nlm.nih.gov/pubmed/17805418
      http://www.ncbi.nlm.nih.gov/pubmed/17119233

      and associated papers.

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  4. Janet Grogan

    Communications provider

    I understand that this corn variety was approved as safe by FSANZ in 2002
    It would be interesting to see how the feeding trial used for safety approval of the corn at that time compares to this study.

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    1. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to Janet Grogan

      Janet, FSANZ will have published an assessment that contains a summary of the feeding studies submitted. You should eb able to find it on their website.

      You should be aware that FSANZ does not require whole food feeding studies for its assessments because they have such low statistical power; however, they will assess them if they are available. FSANZ requires higher powered toxicity studies based on the protein produced by the modificcation.

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    2. Paul Rogers

      logged in via Twitter

      In reply to Christopher Preston

      Christopher, can you say what the 'higher powered toxicity' studies are?

      Acute toxicity, chronic toxicity, carcinogenicity, mutagenicity, teratogenicity, neurotoxicity?

      Which of these? Any others?

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    3. David Tribe

      Senior Lecturer in Food Biotechnology and Microbiology, Agriculture and Food Systems at University of Melbourne

      In reply to Janet Grogan

      Janet

      These links may help you

      Here is FSANZ's analysis of the contentious GM reports, some never published.

      http://www.foodstandards.gov.au/consumerinformation/gmfoods/gmtableofstudies.cfm

      Here is a summary of FSANZ GM food approvals:

      http://www.foodstandards.gov.au/consumerinformation/gmfoods/gmcurrentapplication1030.cfm

      Here is a list of most GM food safety related scientific publications

      http://gmopundit.blogspot.com.au/p/440-published-safety-assessments.html

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    4. David Tribe

      Senior Lecturer in Food Biotechnology and Microbiology, Agriculture and Food Systems at University of Melbourne

      In reply to Paul Rogers

      Paul

      This is test test done in mice to evaluate the added protein in this corn strain

      https://docs.google.com/open?id=0B7hhP5QasNtsb2Q5T05ma2lFUW8
      (full paper, now open access at the journal)

      Summary

      J Nutr. 1996 Mar;126(3):728-40.
      The expressed protein in glyphosate-tolerant soybean, 5-enolpyruvylshikimate-3-phosphate synthase from Agrobacterium sp. strain CP4, is rapidly digested in vitro and is not toxic to acutely gavaged mice.
      Harrison LA, Bailey MR, Naylor MW, Ream JE, Hammond…

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    5. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to Paul Rogers

      Paul, you can find the FSANZ assessment of the corn product here http://www.foodstandards.gov.au/_srcfiles/A416_FAR.pdf

      It summarises the data considered during the assessment.

      The value of straight toxicity studies is that there is a single compound being delivered and a limited number of end-points. This provides the analysis with higher power than if a mixed group of compounds is given and many end-points are measured. For example, OECD guidelines suggest a minimum of 50 individuals in each group for the type of study that Seralini conducted. As the study had 9 different treatments of 3 types, there really should have been multiple control groups - at least 3. Even then, the study may have been underpowered because of the 9 x 47 factor multivariate analysis conducted.

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    6. mark mc dougall

      educator

      In reply to David Tribe

      I might be green but arent part of the comments in this study, that the adjuvants included in roundup need to be included in the testing.
      Makes sense tome? Similarly, in theory one gene might make one protein, but the consequence of that protein, and the breakdowns and the rebalancing that occurs need to all be considered- as we are consuming not just a single gm protein laced food, but a food grown with that protein and all its vital complications.
      Further, we are also eating the dna and rna, which at times maybe denatured, at other times maybe novel. Where these genetic strands interact with viruses or bacteria, under compromised health situations thats where we need multi generational in vivo research.

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    7. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to mark mc dougall

      Dear Mark, the adjuvants are only of interest if you are going to start drinking Roundup herbicide. The adjuvants are compounds like detergents that help the spray droplets stick to the leaves. These are very large molecules that do not enter the plant and hence are not present in any grain that is produced.

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    8. mark mc dougall

      educator

      In reply to Christopher Preston

      So you are saying the adjuvants dont end up in groundwater..and drinking water across the globe? or that there have been tests saying it doesnt? i believe glyphosate salts build up in the soil, so much so that non gm alfalfa now barely germinates in US midwest agribusiness fields?

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    9. David Tribe

      Senior Lecturer in Food Biotechnology and Microbiology, Agriculture and Food Systems at University of Melbourne

      In reply to Paul Rogers

      As far as genetic stability of the construct, this is routinely tested during the several seasons of breeding prior to registration. Additionally, there is a background level on genetic instability in all plants. Extensive studies show that the level of background variation in genetics with conventional breeding is about an order of magnitude greater than seen with transgene construction.
      http://gmopundit.blogspot.com.au/2008/07/gene-chips-prove-transgenes-are-clean.html

      Quantitatively , we face much greater risks from random events from conventional breeds.

      I discuss some of this here:

      https://theconversation.edu.au/frankenfood-or-crops-of-the-future-gaps-in-the-perception-of-gm-food-safety-7713

      Cross breading between plant species, such as the events that generate wheat from other grasses, is a major source of such variation.

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    10. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to mark mc dougall

      Mark, the adjuvants are very unlikely to end up in drinking water unless someone adds them to the water. They are not as water soluble as glyphosate and will become easily bound to soil particles and plant material in rivers - basically anything that has a hydrophobic surface. Water processing will also remove them. Therefore, I don't think it is useful to do studies based on that scenario. There are a lot of studies based on attempted human suicides with glyphosate herbicides. These have indicated…

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    11. Bob Phelps

      Director at Gene Ethics

      In reply to David Tribe

      David: You can't call this FSANZ' rebuttal an analysis as it is just unreferenced rhetoric http://www.foodstandards.gov.au/consumerinformation/gmfoods/gmtableofstudies.cfm

      I asked FSANZ Chief Scientist Paul Brent to post a critical review of the paper on mRNA silencing by Zhang et al on the same page but he emailed: "In response to your request for FSANZ to add an opinion of the Zhang et al., paper on mRNAs to the FSANZ website, after discussing internally with FSANZ scientific colleagues, it…

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    12. Paul Rogers

      logged in via Twitter

      In reply to David Tribe

      David, yes, but one 'qualitatively' catastrophic adverse outcome is bound to be more important than quantitative comparisons of negligible instabilities. Even so, there are scientists more qualified than I to argue the stability (and instability) of GM foods, and the possible consequences.

      Even so, to address the article's main premise, it seems there are no tests for carcinogenicity and mutagenicity required for approval of GM foods. And as Bob Phelps implies, the regulatory system for GM foods is inadequate by any reasonable standards of food safety.

      GM foods may not be "inherently" unsafe, but pre-release testing gives us no assurance.

      I'm sure you are well aware that one well-conceived and conducted study of the Seralini type that shows a higher incidence of cancer for consumption of GM foods will change that in a flash.

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    13. mark mc dougall

      educator

      In reply to Christopher Preston

      so the adjuvants bind to plant matter, but wont end up in the food chain??
      The question isnt of a one off toxicology, it is of repeated continuing dosages
      the alfalfa problem is a recent discovery and not widely acknowledged but seems to be behind the neccessity for the approval of RR alfalfa

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    14. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to mark mc dougall

      Mark, yes that is correct. Their chances of ending up in the food chain are minimal. We don't eat the part of the plant that is sprayed with the herbicide.

      I have checked with my colleages at several Land Grant Universities in the US and none of them have heard about this "alfalfa problem". I can't find any formal reference to it in any of the extension material or farm newsletters. I also know from the chemistry of the chemical that it is exceedingly unlikely. I can't even find it on the internet, which is full of spurious stories about the dangers of GM crops and Roundup. So pardon me if I disbelieve until there is evidence.

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    15. mark mc dougall

      educator

      In reply to Christopher Preston

      Dear Christopher, it is current practise to use roundup as a desicator, ie weathers not too good, round it up cut and roll hay in a few days.
      It is also used to dessicate grains, speed the ripening but for barley it has been banned as it then wont germinate/malt properly - no beer.
      You think the brans and husks dont end up in the food chain?
      Chemistry of life is more active than chemistry in vitro.
      Plants roots via soil processes organisms/bacteria deposit and reuptake glyphosate salts in their…

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    16. mark mc dougall

      educator

      In reply to Christopher Preston

      And add the birth defect possibilities that this study doesnt address, in fact no study addresses,... we have a lot of work to do to find out.

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    17. mark mc dougall

      educator

      In reply to Christopher Preston

      Newtons sleep-Blake
      What to others a trifle appears
      Fills me full of smiles or tears
      For double the vision my Eyes do see
      And a double vision is always with me
      With my inward Eye 'tis an old Man grey
      With my outward a Thistle across my way....

      And twofold Always. May God us keep
      From Single vision & Newtons sleep

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  5. Lee Jones

    logged in via Facebook

    I read the study and saw that the control group was autopsied and reported on . I also note that the SD rat is used in most industry studies on which GM food approvals are based.

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  6. Lisa Hodgson

    Director

    How is it logically or statistically possible for each and every study that demonstrates harmful effects from GMOs is flawed? Why are the pro GMO brigade so confident in the face of *apparent problems with safety that they don’t even want to replicate or take the potential health consequences seriously?

    There is a sweet irony that the author and the pro GMO brigade now screams for raw data. There was virtually no available raw data from Monsanto studies for two decades. Seralini literally had…

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    1. Lisa Hodgson

      Director

      In reply to Lisa Hodgson

      Forgot to say that for Seralini to withhold data relating to a two year study is reasonable given the enormity of the data set. It would be unscientific to attempt to report it all in one 5000 word journal article.

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  7. Mark Myers

    Biomedical Science, Academic

    Thanks for the article. The media coverage and topic also caught my attention and prompted me to read their data from the survival curves and do some stats (survival curves, Wilcoxon, using SPSS). Just for theconversation's record, analysis of the data for the full 725 days for males fed GMO and males fed GMO+R, which are the only 2 that looked like they could be different, did not reach statistical significance.
    This should have been apparent to peer reviewers and to me this is the major concern here, which is further amplified by the controversial nature of the topic.

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  8. MADGE Australia Inc

    logged in via Twitter

    The Seralini study has been published in the most prestigious peer reviewed journal. The internet furphy about the wrong rat, the wrong stats etc are just so much noise to distract from the fact the study shows that GM food urgently needs review. We have been eating this GM corn since 2002. If the damage to rats is replicated in humans we will have a massive health crisis on our hands. This article rebuts the silly net based misinformed criticisms in detail: http://www.campaignforrealfarming.org/2012/09/corrine-lepage-mep-and-founder-of-criigen-speaks-out-against-seralinis-critics/

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    1. Michael Lardelli

      Senior Lecturer in Genetics at University of Adelaide

      In reply to MADGE Australia Inc

      I think this paper would have received better peer review if it had been published in a cancer journal rather than a nutrition journal. the Seralini et al paper was not published in the most prestigious peer-reviewed journal - that would be Nature, Science or Cell for this type of work.

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    2. Laurie Willberg

      Journalist

      In reply to MADGE Australia Inc

      Madge Australia Inc -- thanks for the overwhelmingly enlightening link.
      Let's hope the Seralini study becomes the coffin for GMO products once and for all. There's no possibility of GMOs being whitewashed any further by those who should really bill themselves as Scientists Without Scruples.

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    3. Luke Weston

      Physicist / electronic engineer

      In reply to MADGE Australia Inc

      "has been published in the most prestigious peer reviewed journal"?? So, are we talking "Nature" or "Cell", or are we talking "Green Left Weekly"?

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  9. Sean Lamb

    Science Denier

    "
    The French paper linking GM corn and cancer in rats should have been rejected on a number of grounds"

    I am puzzled by this remark, surely the raw data alone deserved publication. Since this is the first 2 year feeding study of roundup-ready corn, it seems unscientific to demand that the data be suppressed.

    Ideally perhaps the control animals death after 2 years should have been investigated, but it hardly seems the critical important issue that Dr Ng suggests. It is also odd to on one point complain the study is underpowered for its conclusions and then himself try to draw conclusions on individual groups of 10. And even if it is underpowered that is never a reason not to publish.

    It seems like Dr Ng is fully convinced that he already knows the effect of constituitive expression of an aromatic amino acid biosynthesis gene in a plant and doesn't need to bothered by anything so inconvenient as data.

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    1. Ashley Ng

      logged in via Twitter

      In reply to Sean Lamb

      Thanks Sean for your comment.

      By not investigating and reporting all causes of death in the control cohort, the authors have suppressed critical data.

      In doing so, they have invalidated their study.

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    2. Sean Lamb

      Science Denier

      In reply to Ashley Ng

      Not, necessarily, for example if a larger study show a consistent and statistically significant difference in mortality between controls and GM feed rats, that would stand in its own right, even if they were dying of exactly same types of tumor.

      Using artificial animal models is quite normal, you can't get little mousikins to develop atherosclerosis normally, so a specially designed mutant mouse, the ApoE mouse, was created in order to have a system where treatments or risk factors could be evaluated…

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    3. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to Sean Lamb

      Sean, the issue is not that these particular rats were used. The issue is that far too few rats were in the experiment to identify any effects. In these rats up to 85% of females will develop cancers within 2 years. That means 10 rats are far too few to see an increase in the number of cancers. More importantly the authors did not tell the readers this important information.

      Secondly, the data in Figures 1 and 2 when analysed in a sensible way show no statistically significant difference between…

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    4. Ashley Ng

      logged in via Twitter

      In reply to Sean Lamb

      Hi Sean. It would be incorrect to say that no-one has run this type of experiment of this length before. Indeed several groups have done this with this strain of rat.

      Here is one of one of the more recent publications :

      https://www.jstage.jst.go.jp/article/expanim/50/2/50_2_99/_pdf

      The analysis performed in this paper should have been what the Seralini group should have done for all their control and treatment populations, ie. all the rats in each cohort analysed and the diseases documented to establish a true estimate of disease in each population.

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    5. Sean Lamb

      Science Denier

      In reply to Ashley Ng

      That is a very silly comment Dr Ng, it is difficult to understand how you could do this in the spirit of good faith discussion.

      The study you link to is not a 2 year study of GM foods - as you were well aware. A foolish and disappointing strawman. However, it does demonstrate my point that this strain is well characterised and reinventing the wheel was not really necessary.
      You have yet to come up with a rationale that if a controlled study showed a significant difference of longevity between treated and control groups why an exhaustive discussion of the causes of death of the control group would be vital - even if you think it would be desirable.

      Remember, you are trying to make a case for data suppression, that needs fairly strong grounds I believe.

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    6. Sean Lamb

      Science Denier

      In reply to Christopher Preston

      Professor Preston, you seem to be having some difficulty in understanding the statistical concepts. You can't simultaneously complain about a study being underpowered and the results not being statistically significant. Of course an underpowered study won't provide statistical significance - thats tautology.

      However, being an underpowered study is not an argument against publication. As the authors' indicate in their discussion they were surprised to see an effect from GM feed alone, hence…

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    7. David Tribe

      Senior Lecturer in Food Biotechnology and Microbiology, Agriculture and Food Systems at University of Melbourne

      In reply to Sean Lamb

      Sean,
      Gratuitous personal comments don't help the discussion or strengthen your argument.

      The main point of mentioning these other studies is that they illustrate comparisons and criteria CRIIGEN don't supply, and they establish data on the base level of tumour incidence expected in untreated rats. It is very high and displays sporadic variation in small samples, so differences can occur by chance. This means lots of rats need to be examined if the differences are to be attributed to cause and…

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    8. Sean Lamb

      Science Denier

      In reply to David Tribe

      "Gratuitous personal comments don't help the discussion or strengthen your argument."

      I stand by my comment that attempting to pass off a 2 year study as a 2 year GM feeding study was silly and difficult to see as being done in good faith. If you think this good practice then we operate to different standards.

      I agree that I would like to see blinded experimentation but this is virtually never done in university research, or indeed in any research unless their is a specific legal regulatory…

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    9. David Tribe

      Senior Lecturer in Food Biotechnology and Microbiology, Agriculture and Food Systems at University of Melbourne

      In reply to Sean Lamb

      "I stand by my comment that attempting to pass off a 2 year study as a 2 year GM feeding study was silly and difficult to see as being done in good faith"

      I put it to you that assertion this is solely your own imagined scenario.

      "Again, like others here, you seem to have already made up your mind that there can be no possible repercussions from uncoupling the aromatic amino acid biosynthesis pathway from biological controls "

      In what way is -- preventing an existing constitutuve non rate limiting reaction from being inhibited by added herbicide --- uncoupling the aromatic biosynthesis pathway from controls? The biological feedback inhibition controls by amino acid end-products act at other steps in aromatic synthesis, such as 3-deoxy-arabino hepulosonic acid 7-phosphate synthetases, and the chrorismate mutases and anthanilate synthases, and remain in effect in the transgenic plant.

      I haven't closed my mind though, but do seek plausible hypotheses of risk.

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    10. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to Sean Lamb

      Sean, you seem to have mixed up my concerns. The study was underpowered from the start. Therefore, it was likely to give only low confidence of finding a statistically significant result. (You may not be aware that it is possible to get a statistically significant result through chance in a low-powered study.) Having an under-powered study can be an argument against publication, because it means the data do not support the conclusions.

      More importantly, the authors did not get a statistically…

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    11. Stiofán Mac Suibhne

      Contrarian / Epistemologist

      In reply to Christopher Preston

      Surely the thing to do is to attempt to repeat the study with larger numbers. Science had not been outlawed! If it is a blip resulting from the tyranny of small numbers then we can all calm down. If the results are not statistical mirages then there is a problem that needs the attention of governments PDQ.

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    12. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to Stiofán Mac Suibhne

      Stiofan, the short answer to your question is "It depends". A larger study should only be conducted if there is a reasonable hypothesis to be tested. Otherwise, large numbers of rats will be killed for no good reason. So the first question that needs to be asked is "What is the hypothesis". It is no good just plucking an idea out of the air, a hypothesis needs to incorporate all the information already known.

      I have in the past been critical of the animal feeding studies on GM food conducted…

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    13. Ashley Ng

      logged in via Twitter

      In reply to Sean Lamb

      Sean

      There have been 24 long term GMO feeding studies, several extending to 2 years including multi-generational follow up and presented in this review (published this year in the same journal which published the Seralini paper)

      http://note.io/QRyWfK

      None had detected any statistically significant difference in disease between control and GMO fed groups, in a variety of species and with several types of GMO foods.

      That's why the claims of Seralini group were surprising. Examining their…

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  10. David Tribe

    Senior Lecturer in Food Biotechnology and Microbiology, Agriculture and Food Systems at University of Melbourne

    There is another study available for free access on line that illustrates most 2 year old female rats have tumours (including mammary tumours) AND high numbers have kidney pathology on normal lab diet.
    This raises further questions about the validity of several claims by CRIIGEN

    http://tpx.sagepub.com/content/33/4/477.long
    Incidences of Selected Lesions in Control Female Harlan Sprague–Dawley Rats from Two-Year Studies Performed by the National Toxicology Program
    Amy E. Brix, Abraham Nyska, Joseph K. Haseman, Donald M. Sells, Micheal P. Jokinen and Nigel J. Walker
    http://tpx.sagepub.com/content/33/4/477/T1.expansion.html
    (Table 1)

    These problems with ageing SD strain lab rats were also reported also in the 60s and 70s so they pre-date introduction of GM corn.

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  11. David Tribe

    Senior Lecturer in Food Biotechnology and Microbiology, Agriculture and Food Systems at University of Melbourne

    There is one other 2 year feeding trial of GM feed done with rodents. The repot and the experiments show how to avoid most of the scientific mistakes made by CRIIGEN

    A 104-week feeding study of genetically modified soybeans in F344 rats.
    see
    http://gmopundit.blogspot.com.au/2012/09/the-first-long-term-2-year-study-of-gm.html
    [Article in Japanese]
    Sakamoto Y, Tada Y, Fukumori N, Tayama K, Ando H, Takahashi H, Kubo Y, Nagasawa A, Yano N, Yuzawa K, Ogata A.
    Shokuhin Eiseigaku Zasshi. 2008 Aug;49(4):272-82…

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    1. Paul Rogers

      logged in via Twitter

      In reply to David Tribe

      David, yes, that type of study should be mandatory at the regulation and approval stage for all new GM foods.

      Agree?

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    2. Sean Lamb

      Science Denier

      In reply to David Tribe

      Although this study also showed a trend towards increased incidence of tumors in GM over non-GM feed animals.

      Thats two studies out of two, one more and we can do a meta-analysis.

      I do hope you now understand the difference between not statistically significant and random variations.

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    3. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to Sean Lamb

      Sean, sorry, but the Japanese study does not show a trend towards increased incidence in tumours. There was no statistical difference in the total number of rats with tumours. In fact the proportion of rats with tumours in the GM feed was slightly lower than for the control feed.

      When they conpared individual tumours, non-GM food had a significant difference for 4 of the 40 tunour types (you would expect 2 false positives simply through chance with this many tests) and GM food has a significant difference for 3 of the 40 tumour types. So the conclusion has to be that neither GM feed, nor Non-GM feed increased the amount of cancer.

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    4. Sean Lamb

      Science Denier

      In reply to Christopher Preston

      Sorry Professor Preston
      GM feed male rats 39/50
      Non-GM feed male rates 33/48

      GM feed female rats 35/49
      Non-GM feed rats 32/50

      Total
      GM feed 74/99
      Non GM feed 65/98
      Looks like a trend to me

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    5. Christopher Preston

      Associate Professor, Weed Management at University of Adelaide

      In reply to Sean Lamb

      Sean, you are aware that 80% of the male and 80% of the female rats fed commercial rat chow developed cancers? The frequency of rats with tumours for GM food was 71% for female rats and 78% for male rats. I am struggling to see a trend.

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    6. Sean Lamb

      Science Denier

      In reply to Christopher Preston

      Clearly soybeans are good for you! But not so good if they are overexpressing a component of the aromatic acid biosynthesis.

      The commercial chow is a spurious control, if the outcomes were reversed and you were comparing GM against commercial chow to the detriment of the GM product, the Internet would not be able to contain your howls of outrage.
      Against the appropriate control it shows a trend - something which you attempted to conceal in your typical bad faith debating style.

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  12. MADGE Australia Inc

    logged in via Twitter

    It is useful to look at the statements by the scientists that did the NK603 study. http://www.gmwatch.org/latest-listing/51-2012/14250-dr-spiroux-co-author-of-the-shocking-study-responds-to-criticisms The S-D rats are the type commonly used for testing and therefore there is no surprise in their being used for this study. Previous research (done by Monsanto and re-analysed by Seralini) showed liver and kidney toxicity at 90 days and so this was a toxicological study.

    "The study protocol for…

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  13. MADGE Australia Inc

    logged in via Twitter

    Any scientist who finds problems with GM crops is subject to sustained attack in the media. This article (written by scientists) dissects what is going on. http://independentsciencenews.org/health/seralini-and-science-nk603-rat-study-roundup/ They show deceptive media reporting that mostly does not attempt to fairly discuss the science.

    " A key pattern with risk-finding studies is that the criticisms voiced in the media are often red herrings, misleading, or untruthful. Thus, the use of common…

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  14. David Tribe

    Senior Lecturer in Food Biotechnology and Microbiology, Agriculture and Food Systems at University of Melbourne

    The reason for sustained criticism of this CRIIGEN study is that it is bad science. This official report from the German Federal Food Safety Agency shows that Ashley Ng has only touched the tip of the iceberg of the problems in this publication.

    Update
    Official English translation of main report

    http://www.bfr.bund.de/cm/349/feeding-study-in-rats-with-genetically-modified-nk603-maize-and-with-a-glyphosate-containing-formulation-roundup-published-bei-seralini-et-al-2012.pdf

    Feeding study…

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