Skip to main content

Rats, Tumors and Critical Assessment of Science



My email box exploded with new messages.  A flurry of notes contained a link to a new peer-reviewed paper, a work showing that rats fed “GMO” corn developed massive tumors and died early, compared to controls.  Immediately I smelled a Seralini paper.

A click on the link did not disappoint-- it's Seralini again.  I was electronically whisked to a PDF of the whole text and began to read.  Within minutes I was blown away by the lack of rigor, poor experimental design, attention to controls and loose statistics.  Most of all, I was blown away by the conclusions drawn by a study with tiny numbers of subjects in a rat line known to grow endochrine tumors.

The anti-GMO interests were quick to anoint this new work as a rigorous pillar of exceptional science, a hard-science detailing of the danger of transgenic food.  They want this to influence public policy.

I was really impressed by how the scientific media and the science blogosphere pounced.  The best names in the business, Terwavas, Leyser, Goldberg and many others were interviewed and provided detailed analysis of the work, pointing out its many flaws.  Those reviews can be foundthroughout the internet, and they are awesome. Like this one! I don’t need to reiterate them here.

What I will do, which is highly uncharacteristic and but consistent with the post hoc analysis done all the time, is provide a level of analysis that was not explored.  There are features of this paper that hint at a motive, an intent.  I do not believe this was a hypothesis tested.  I believe that this was an experiment designed to frighten.  I believe that this is blatant mis-use of science to forward an agenda.

Those are strong words and I never thought I’d cast such allegations at someone else’s peer-reviewed research.  That’s usually pretty low.  However, there are facets of this work that are clearly indicate the intent of the authors is to provide shock, not a good test of a hypothesis.  In fact, the word “hypothesis” does not appear once.  

This is why the report is in Food and Chemical Toxicology and not in Nature, where it would be if it was a properly conducted study.

Here are some red flags the others have not mentioned.  I’m reading between the lines here. I will describe what a good scientific report should not do and then give you some strong inferences from what the paper does not show, as well as how data are presented.

1. The first line of the paper claims an “international debate”, yet he cites himself and nobody else.  Easy to claim a debate when nobody else is participating in it.

2.  Figure 3.  This one really makes me see red.  Look at tumors.  Look at massively deformed rats.  Shocking, isn’t it?   The authors tell us in Table 2 that control rats also develop tumors.  Why not show them?  Why are the controls not shown in that figure?  It is because if they are identical to the experimental treatment rats then the fear factor is gone.   This is inexcusable and the authors, reviewers and editors should be ashamed.

Sometimes the way data are presented can expose the relative objectivity and hidden intent of a study. Left-rat that ate GMO corn.  Center- rat eating GMO corn and roundup. Right- rat fed roundup. Their associated tumors shown on the right. Wait!  What about the control rats, the ones that also got tumors?  How convenient to leave them out!   

3.  The labeling on the figure is “GMO” or “GMO+R” (R stands for Roundup).  GMO is not a product. It is not a genetic line of corn.  It is a technique.  There are many kinds of GMOs, plant lines bearing different transgenes.  Even if these results linked rat tumors to the food (which they don’t in my assessment) they would  link it to one kind of transgenic crop, not any transgenic crop.  This again shows the authors’ intent to overstep the data in a manner that will inflame the reader and further vilify a technology. To be fair, they do state it properly in the conclusion, but few are reading past the sensational photos.

4.  They show comparable effects of Roundup treatment and the transgene.  This should be a tip-off as well.  What is the likelihood of both inducing identical problems?

5.  Low numbers of subjects are a sign of poor design.  When tumor incidence is 30%, vs 50% or 70% that means three rats vs. five or seven.  The incidence of endocrine tumors in Sprague-Dawley rats is 70-80%.  Imagine you roll a die and numbers 1-4 mean develop tumors, 5 and 6 mean tumor free.  Now roll it ten times and log the result.  You’ll find that there will be times when you consistently roll 5 or 6, maybe 5 times out of ten.  Other times you’ll roll 5 or 6 only 2 times out of ten.  That’s natural random variation, and if you roll it 100 times, 1000 times, then the real probabilities will even out. 

6.  Low numbers + a line known to get tumors = some frequency of data that will prove the authors’ beliefs.

7.  A prediction-- the larger study will never be done and these results will not replicated by other labs.

8.  The Discussion.  Lots of guesses on how to link the food or Roundup to the symptoms. Quite a bit of speculation and hand waving, with no likely mechanisms discussed.

I could go on all day. For fun reading review the press conference. It was a bigger joke.  

The bottom line is that if we look at the report and what it says, and compare it to what the data really say, there is limited concordance.  To the trained eye the data say that these rats get endocrine tumors at high incidence and that what is being observed is the natural variation of the tumors in small numbers of rats, where the authors'  “significance” is found in statistically meaningless samples.

Alas, it is now part of the true-believers' war chest of crap information that now will be used to steer the unsophisticated and influence public policy. 

Popular posts from this blog

Scientific American Destroys Public Trust in Science

This is a sad epitaph, parting words to an old friend that is now gone, leaving in a puff of bitter betrayal. 
When I was a kid it was common for my mom to buy me a magazine if I was sick and home from school.  I didn't want MAD Magazine or comic books.  I preferred Scientific American
The once stalwart publication held a unique spot at the science-public interface, bringing us interesting and diverse stories of scientific interest, long before the internet made such content instantly accessible.  It was our trusted pipeline to the new edges of scientific discovery, from the mantle of the earth to the reaches of space, and every critter in between.
But like so much of our trusted traditional science media, Scientific American has traded its credibility for the glitz of post-truth non-scientific beliefs and the profits of clickbait.The problem is that when a trusted source publishes false information (or worse, when it hijacked by activists) it destroys trust in science, trust in s…

Chipotle's Ag-vertising to Fix their Anti-Ag Image

After years of anti-farmer rhetoric, disgusting anti-agriculture videos, and trashing farmer seed choice, Chipotle now seems to have found a love for the American farmer that is as warm and inviting as the gooey core of a steak burrito.  Their new "Cultivate the Future of Farming" campaign raises awareness of the hardship being experienced in agriculture, and then offers their thoughts and some seed grants in order to reverse it. 

But are they solving a problem that they were instrumental in creating? 

The crisis in agriculture is real, with farmers suffering from low prices, astronomical costs, and strangling regulation.  Farmer suicides are a barometer of the crisis.  Farms, from commodity crops to dairies, are going out of business daily. It is good to see a company raising awareness. 


From Chipotle's website- The "challenge is real" and "It's a hard living"-- and companies like Chipotle were central in creating those problems. 

However, Chipotle&#…

Mangling Reality and Targeting Scientists

Welcome to 2019, and one thing that remains constant is that scientists engaging the public will continue to be targeted for harassment and attempted reputation harm.  

The good news is that it is not working as well as it used to.  People are disgusted by their tactics, and only a handful of true-believers acknowledge their sites as credible. 

But for those on the fence I thought it might be nice to post how a website like SourceWatch uses a Wikipedia-mimic interface to spread false and/or misleading information about public scientists. 

Don't get me wrong, this is not crying victim.  I'm actually is screaming empowerment.  I spent the time to correct the record, something anyone can check.  Please look into their allegations and mine, and see who has it right. 

This is published by the Center for Media and Democracy.  Sadly, such pages actually threaten democracy by providing a forum for false information that makes evidence-based decisions in policy issues more challenging.  It…