Medical Doctors weigh in on Glyphosate Claims

posted in: Science | 111
Dr. Steven Novella

Before the Holidays, a claim was being circulated around about glyphosate – the active ingredient in Roundup herbicide. The claim is that half of all children will be autistic by 2025 – and the source for this claim is none other than Dr. Stephanie Seneff. Long-time readers of this blog will recognize that she has made many claims about GMOs – in particular the Roundup herbicide that is sprayed on them – which have been addressed many times before. Is there any merit to this claim? Two highly-regarded blogging medial doctors have weighed in on this issue with a resounding no. Dr. Steven Novella, who writes at Science-Based Medicine, and the pseudonymous Orac a.k.a. Dr. David Gorski, who writes at Respectful Insolence, both evaluated Dr. Seneff’s claims and found them to be based on poor logic, bad science, and straight-up falsehoods – and completely wrong.

Steven Novella writes at Science Based Medicine, Glyphosate – The New Bogeyman.

There is an ideological subculture that is motivated to blame all the perceived ills of the world on environmental factors and corporate/government malfeasance. Often this serves a deeper ideological drive, which can be anti-vaccine, extreme environmentalism, or anti-GMO. The latest environmental bogeyman making the rounds is glyphosate, which is being blamed for (you guessed it) autism.

Glyphosate is the active ingredient in the herbicide Roundup. It has been widely used for about 40 years, and with the introduction of GM crops that are Roundup resistant, its use has increased significantly in the last 20 years. It has therefore become a popular target for anti-GMO fearmongering.

He provides many useful links to meta-analyses and scientific reviews of glyphosate that point toward its relative safety.

The current article spreading fears about glyphosate cites the work of Stephanie Seneff, making a clear argument from authority:

For over three decades, Stephanie Seneff, PhD, has researched biology and technology, over the years publishing over 170 scholarly peer-reviewed articles. In recent years she has concentrated on the relationship between nutrition and health, tackling such topics as Alzheimer’s, autism, and cardiovascular diseases, as well as the impact of nutritional deficiencies and environmental toxins on human health.

Seneff, however, has not actually performed any research into glyphosate. She is “a Senior Research Scientist at the MIT Computer Science and Artificial Intelligence Laboratory.” She is also an anti-GMO activist. That does not mean she is wrong – it just means it is misleading to cite her as a researcher and authority. She has published only speculations and gives many presentations, but has not created any new data.

Dr. Novella gives a quick rundown of what is wrong with her claims about glyphosate and autism, but Orac goes into great detail at Respectful Insolence, in his post Oh, no! GMOs are going to make everyone autistic!

I must admit, when I clicked on the link to the “correlation,” I couldn’t stop laughing. It was one of the most hilarious examples of confusing correlation with causation that I’ve ever seen. Take a look:

“Orac”, a.k.a. Dr. David Gorski

As I’ve pointed out time and time again, if you look at two different variables that have shown an increase with time, you can almost always make it look as though there’s a correlation. Only occasionally does that correlation equal causation. It was that claim that the “autism epidemic” began (i.e., autism prevalence started increasing dramatically) beginning in the early to mid-1990s and that that correlated with an expansion of the vaccines in the vaccine schedule or, in the US, that it correlated with the addition of mercury-containing vaccines to the vaccine schedule. From these observations, it was claimed, that it had to be the vaccines, or the mercury-containing preservative thimerosal used at the time in some childhood vaccines, that was causing autism. Lots and lots of epidemiology since then has confirmed that there is no detectable link, epidemiology that I’ve written about time and time again, but that hasn’t stopped the antivaccine movement. What the increase in autism prevalence corresponds to is really the expansion of diagnostic criteria for autism spectrum disorders that occurred in the early 1990s as well as increased screening for the condition, which, as I’ve pointed out, will always increase the prevalence of any condition.


In fact, if you look at the slides for Seneff’s talks (e.g., this one, available at her MIT web page), you’ll find a tour de force of confusing correlation with causation, complete with a version of the first graph above, plus similar graphs purporting to correlate glyphosate use with deaths from senile dementia (gee, you don’t think that deaths from senile dementia might be rising because the population is aging and dementia is usually a disease of the elderly, do you?), obesity, celiac disease, deaths due to intestinal infection, and kidney disease death rate. She even cites the horribly done “pig stomach” GMO study that I deconstructed a while ago.

But what about Seneff’s prediction that half of all children will be autistic by 2025, which is only ten years away? Well, take a look at this graph in her talk:


Yes, she just extrapolates from current trends, assuming they’ll continue indefinitely! It’s almost as stupid as Julian Whitaker’s mind-blowingly idiotic extrapolation that predicted that 100% of boys will be autistic by 2031, with 100% of all girls autistic by 2041. Almost. It’s pretty close, though.

Unfortunately, I know something worse. Dr. Stephanie Seneff blames Roundup for school shootings and the Boston Bombings, as she states in this interview with Jeffrey Smith. Apparently, everything wrong with the world is caused by glyphosate.

Dr. Novella sums it up.

Dr. Seneff gives every indication of being an anti-GMO ideologue. She is not a biologist, but rather is a computer scientist, and yet she is being presented as an expert. She has also not conducted any original research, but is spreading fears about glyphosate based on pure speculation, bad science and bad logic.

Meanwhile, numerous published systematic reviews show clear evidence that glyphosate has very low toxicity. More careful study when it comes to any agent being used as heavily as glyphosate is always welcome. Science is complicated, and it is always a good idea to consider factors that may have been previously missed. However, failure to show any adverse effect from glyphosate in epidemiological studies is very reassuring. Given its widespread use, any adverse effect must be tiny or non-existent to be missed by the evidence we have so far.

The evidence, however, will not stop ideologues from cherry picking, misusing evidence, presenting pure speculation as if it were evidence, assuming causation from correlation, and generally fearmongering about a safe chemical in order to grind their ideological axe.

Finally, Orac finishes it with his characteristic wit.

The bottom line is that the crank magnetism is strong in Dr. Seneff. She’s antivaccine and anti-GMO. She is full of Dunning-Kruger, thinking that she can transfer her computer science and artificial intelligence knowledge to knowledge of epidemiology, biochemistry, and medicine. She can’t. Happy New Years.

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Karl earned his Ph.D. in Plant Breeding and Plant Genetics at UW-Madison, with a minor in Life Science Communication. His dissertation was on both the genetics of sweet corn and plant genetics outreach. He recently moved back to his home state of California. His favorite produce might just be squash.