Sep 30 2014

Dr. Oz, Autism, and GMOs

It is no longer news that Dr. Oz has long ago abandoned any pretense to scientific rigor and is simply another scaremongering hawker of snake oil and nonsense. Still, it’s hard not to marvel when he sinks to a new low.

On a recent show Oz’s target was genetically modified organisms (GMO). This is not new for Oz, he has hosted anti-GMO activists in the past, warning his audience about non-existent health risks.

This time around Oz and his guest are claiming that pesticides used with certain GMO varieties may cause autism. Why is it always autism? It’s likely at least partly due to the fact that awareness of autism has been increasing in the last 2 decades, creating the false impression that autism itself is increasing. This leads to numerous false correlations (most famously with vaccines) and the assumption of cause and effect (often to support a preexisting bias). As you can see from the graph, however, the rise in autism diagnoses tightly correlates with increased organic food sales – but I guess you have to cherry pick the correlation you want.

The narrative that Oz spun for his audience was this: GMO is tied to pesticide use. Those pesticides are hazardous to your health, and specifically might cause autism. Organic food is pesticide free, and going organic can actually cure autism.

Every link in that chain of argument is misleading or patently wrong.

To help him spin this tale he had on as a guest anti-GMO activist Zen Honeycutt from Moms Across America. In a march against GMO she gave a speech, saying:

I am here today because of love. We are all here because we love our families, our communities, our freedoms, our environment, our dogs and cats, our bees and butterflies. We love our farmers and we have FAITH in our farmers. We have faith that they can and will farm as has been done for thousands of years, without GMOs containing foreign proteins and the use of toxic chemicals.


Today, young couples have a 30% “failure to conceive” rate. That is the lowest in recorded US history. Everyone needs to know about GMOs!

She is a clever propagandist. She doesn’t actually say here that GMOs cause fertility problems, but the implication is unavoidable. She links GMO explicitly to “foreign proteins” and to pesticide use. What are “foreign proteins?” Proteins are just proteins. Most are broken down in the stomach and intestine and become amino acids – food.

Some proteins can resist this breakdown, and they have a greater tendency to cause an allergic reaction. This is why proteins introduced into food through GMO are tested specifically for sequences known to confer resistance to digestion, to cause allergy, or to cause toxicity. There have been no reported cases of allergic reactions to GMO food. 

Let’s unpack further Oz’s anti-GMO narrative. First, GMO is not specifically about conferring resistance to herbicides. Glyphosate resistant crops are among the most common already approved and on the market, but that has nothing to do with GMO itself. Genetic modification can be used for a variety of purposes, such as disease resistance, drought tolerance, enhanced nutrition, and pest resistance. There is research underway to use GM technology to reduce reliance of nitrogen fertilizer, enhance photosynthesis and therefore yield, and to enhance the flavor of commercial cultivars.

Oz, however, wants his audience to link GMO to pesticides. Even here the story is more complex. Current GMOs, specifically Bt varieties, have reduced the use of insecticides. This has been a boon to farmers, reducing costs and exposure to insecticides, and also has been beneficial to the environment. Overreliance on single methods of insect control can lead to resistance, but this is an issue of overall farming practice, and not specific to GMOs.

GMOs, specifically Roundup Ready or glyphosate-resistant varieties, have increased the use of glyphosate (that is the point of these varieties). Again, overreliance on single methods of weed control is probably not sustainable, but we have to consider the big picture. Glyphosate is actually less toxic than many other herbicides it is displacing. Also, tilling the soil to reduce weeds is bad for the soil and releases carbon into the atmosphere. Hand weeding is labor intensive. So – there is no great option, and it’s simplistic to say that using glyphosate is worse than any other option.

I acknowledge that Roundup Ready crops do encourage over use of this single method of weed control, which is already resulting in resistant weeds. A more integrated approach is better – similar to the intelligent use of antibiotics to avoid resistance. Farming practice is the real issue here, and glyphosate-resistant crops should be looked at as one tool among many. Don’t blame the technology, however, if it is not being used optimally.

What apparently triggered this Oz episode is the fact that a new herbicide resistant crop is coming on the market. Dow AgroSciences (not Monsanto this time) is coming out with Enlist Duo. These are crops that are resistant to two herbicides, glyphosate and 2,4-D choline.

2, 4-D was approved in the 1940s and is already one of the most commonly used herbicides in the world. The EPA has determined that it is safe for its intended use.

Oz and his guest imply a link between pesticide exposure and autism. No such causal link has been established, however.

Amazingly, Honeycutt specifically claims that when she switched her family to all organic diet, within 8 weeks he son’s symptoms of autism resolved. Even if autism were the result of pesticide toxicity, this is a highly implausible claim. Autism is the result of developmental changes in the architecture of the brain. This is not something that can change within weeks. The claim is patently absurd, but is likely to scare a lot of parents, and that was the point.

It is also not necessarily true that organic produce has less pesticide. Organic farmers can use “natural” pesticides, and often have to use more because they are less effective than some synthetic pesticides. There is also no particular reason to assume that “natural” pesticides are more safe than synthetic pesticides – this is just a naked naturalistic fallacy.


In my opinion, Dr. Oz systematically misinformed his audience for propaganda purposes, to fearmonger about GMOs. Fearmongering is also good for ratings, so I guess it was a win-win.

There is a meaningful discussion to be had about the regulation, patenting, and use of GMOs. It is unfortunate, however, that public discourse is dominated by pseudoscientific and often outright false claims, largely perpetrated by GMO opponents.

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