Sunday, March 30, 2014

A Fishy Attempt To Link Glyphosate and Celiac Disease

Celiac is real.  The glyphosate link isn't

Stephanie Seneff (a computer scientist at MIT),  and Anthony Samsel (a retired consultant), have recently been attempting to link the use of the herbicide glyphosate to a long list of modern maladies. Their latest such attempt to is Celiac disease.  The overall argument for the glyphosate/Celiac link has already been quite thoroughly debunked by a Celiac expert, but there is one other good reason to dismiss the "link" which I would like to describe.  It has to do with a "Fishy" study about glyphosate and fish which is so flawed that it should never have been published in the first place.  That is why it can't be used to support this chemical/disease link.

The Fishy Study

Samsel and Seneff cite a publication by Indian scientists from 2009 (Senapati et al). In that study, ugly effects were observed in the digestive track of the fish that were exposed to water containing a glyphosate-based herbicide.  Such a finding would be surprising, because for decades, glyphosate has been a preferred method of weed control in aquatic settings, specifically because it has unusually low toxicity to fish and other aquatic organisms.  Glyphosate is particularly valued by the people who are trying to control invasive weeds in wetlands, lakes etc. as described here for CA, WA and FL.  They spray it on the part of the weed that is above the water because that is the only way it is effective, but obviously some glyphosate gets into the water.  Still, this use has long been considered to be safe for fish.  Did this paper document a previously unrecognized issue?

In their analysis of the Indian fish study, Samsel and Seneff concluded that the effects observed on the fish digestive systems were "highly reminiscent of Celiac disease." To me, the effects sounded much more reminiscent of surfactants.  Fish are very sensitive to those.

When I read the Senapati article, it quickly became obvious that this was indeed the problem.  These researchers specifically stated that they used a commercial formulation of glyphosate manufactured in India called Excel Mera-71.  A quick web search shows that Mera-71 is a formulation made for terrestrial, not aquatic use. The manufacturer describes it as containing glyphosate and "a blend of non-ionic and cationic surfactants." At least in the US, products registered for use on weeds growing in water do not contain surfactants because surfactants are well known to injure fish. There was no surfactant control, so the reviewers of the Senapati study should never have let them conclude that the effects were from exposure to glyphosate. It is much more likely that the fish were injured by the surfactants.

Fish Abuse

NOOOO! Not another water change!

There were other experimental design problems with the Senapati study.  They chose to put the fish into water containing 4mg/L of glyphosate.  To achieve that sort of concentration by spraying weeds in even shallow water would have required spraying the weeds above the water at many times the maximum rate allowed. (Here is an EPA label for a glyphosate product for use on weeds in water - AquaMaster). Then, to make matters worse, the water in which the fish were being kept was replaced every other day for 45 days with a fresh solution of 4 mg/L glyphosate along with the inappropriate surfactants.  That would not correspond to any imaginable use-scenario in the real world. So basically, Senapati et al abused several poor fish for more than six weeks to demonstrate what was already well known - surfactants hurt fish.  The only thing remarkable about the study is that the fish even survived. Glyphosate is still a good option for the control of aquatic weeds.  No, it does not cause Celiac.

Some Additional Thoughts About The Scientific Process

This study was a "literature-only" review which involved no actual experimentation.  That can be ok.  The literature is there to be the subject of scholarship.  On her own web page Seneff explains that she places her work in the "open access journal," Entropy, because it is "willing to publish novel hypotheses," and because  "the papers are subjected to rigorous review by experts who were not beholden to industry influence."  That can be ok too as the making of hypotheses is the starting point for the scientific method and unbiased reviews are important for science.  However, if one is going to attempt to do science this way you can't assume that every paper you find actually shows what it claims to show, even if it's what you would like it to show.   If these authors wish to review papers this far outside of their own discipline and training, they would do well to confer with people more familiar with these topics. I would be happy to recommend such resources for future publications.

In science, even when research is published in a "peer reviewed" journal, that does not finish the vetting process.  Particularly if some new finding challenges previously accepted ideas, the next stage is critical.  Does the work hold up to scrutiny by the broader scientific community?  Can the results be repeated by others?  The Senapati and Samsel /Seneff papers fail to pass these tests.  Researchers that are really trying to understand conditions like Celiac disease will continue to look at other, more likely causes.  Unfortunately, in the extensive, anti-technology sector of the internet, this new "link" will likely live on and joint the list of other myths about food and agriculture.

Celiac micrograph image from Wikimedia Commons
Unhappy Fish Image from Kiler129's Photostream

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