Aug 28 2014

Bt and Leukemia – Another Anti-GMO Myth

The headline of an article on the Organic Consumers Association proclaims, “New Study Links GMO Food To Leukemia.” The same article trumpets the thoroughly discredited Seralini study. The claim is not true, but is part of a pattern of behavior that is depressingly familiar.

The pattern is not unique to anti-GMO activism. In fact, it seems to be the default human behavior. We tend to search for information that supports our currently held views. The more passionate we are about those views, the more industrious we are in finding apparent support, even if it means twisting and distorting information.

I find myself doing this all the time – if a study or new piece of information directly opposes something I currently believe, then my mind immediately starts finding reasons to dismiss the information. I have the opposite reaction when the information confirms my current beliefs, I find reasons to accept it.

But then I consciously step back and try to take an objective look at the information. This is not always easy, and may involve specialized knowledge I don’t have. I then have to look to experts to see if there is a clear consensus opinion. In other words, I don’t just stick with my knee-jerk reaction to information. I go through a process of evaluation and critical analysis. My goal is to come to a valid conclusion, one that will hold up under critical assault, whatever that conclusion is. Meanwhile I have to remain open to the possibility that my conclusion is wrong or incomplete, that I missed something or made an error in my process.

This is what scientific skepticism is – a dedication to process over belief and an openness to correction and change. It’s difficult and can even be painful, but the alternative is to be trapped in a world of subjective validation and confirmation bias that can be completely disconnected from reality.

And it gets worse, because we are social creatures, and not just all acting individually. This means that confirmation bias can take on a social dimension with cultural reinforcement, networks of targeted misinformation, and echochambers of reinforcement and amplification. We end up with communities of individuals with extreme views apparently backed by lots of information, but completely insulated from reality.

At the heart of this process is often a distortion of science, which is inherently messy, confusing, and ambiguous. While science as a process slowly moves us in the direction of truth, it generates a great deal of noise along the way, and this is ample fodder for confirmation bias (which then has the patina of scientific backing).

So what about the study showing an alleged “link” between GMO and leukemia? Biofortified does an excellent analysis of the article, but here are the highlights:

The fatal flaw in this study from my perspective is that they compared Bt spores with water. The bacterial spores contained only 20% Bt by dry weight, the rest are other stuff in the bacteria.  A proper control would have been wild-type bacteria without Bt. So, the study cannot conclude that any effect seen was due to Bt. There are good reasons to suspect it wasn’t , including prior studies with purified Bt showing no such toxicity.

Other problems include a small sample size, lack of proper dose-response curve, and the fact that the mice were fed doses orders of magnitude greater than potential human exposure.

The paper itself has a curious history. It was originally published in a respected journal, Food and Chemical Toxicology – but the paper was later withdrawn. It was then republished in  volume 1 issue 1 of a new journal, the Journal of Hematology and Thromboembolic diseases. It’s not clear why this happened, but it’s curious.

This is exactly the kind of study that makes up the background noise of scientific publications – small study, using high doses, with curious results (lack of dose response) consistent with noise, with serious methodological issues, and published in an obscure new journal.

This, however, is frequently the kind of evidence that makes up the standard talking points of ideological groups engaged in aggressive confirmation bias.

I also have to wonder if the  Organic Consumers Association has any cognitive dissonance over this study. The authors did not use purified Bt toxin, they did not use GMO plants with Bt, or toxin taken from such plants. Rather, they used bacterial spores containing Bt. Ironically, this is exactly what is allowed for use in organic farming. In fact the OCA themselves report:

“The naturally-occurring soil bacterium, Bacillus thuringiensis (Bt), is used as a non-toxic pesticide by at least 57 percent of organic farmers,”

In fact this study is much more relevant to the Bt pesticide used by organic farmers than GMO containing Bt, because it used the whole bacterial spore.  It would have been more accurate to publish a headline declaring, “New Study Links Organic Farming to Leukemia.” (To be clear, I am not saying this headline is justified, just that the cited study, if anything, is more relevant to organic farming than GMO.)


The Bt spore study is a deeply flawed study and it is unclear if we can draw any meaningful conclusions from it. At best it is a preliminary study and it would be reasonable to do follow up studies to see if the result is real and if it has any implications for our food chain.

The study absolutely does not justify publishing articles claiming a link between GMO and leukemia, but this now has become a talking point among anti-GMO activists.

This is also not an isolated incident, but indicative of a pattern of behavior – cherry picking evidence, misrepresenting evidence, and generally promoting misinformation.

Whenever I make such observations about any ideological camp, it is common for some to object, saying that I am picking on the worst examples that are not representative of the group. Further, this does not mean there aren’t rational people who have legitimate reasons to oppose GMO (or vaccines, or doubt climate change, or whatever).  This often becomes a “no true Scotsman” argument – that the “real” reasons for opposing GMO are something other than what was discussed in the article and “real” activists know this.

First, I agree that there is often a range of positions, some more reasonable than others. Not everyone occupies the extreme end of the spectrum. Also, most complex scientific issues have legitimate points of controversy and disagreement. Corporations often act badly, governments often try to cover up incompetence, etc.

However, none of this is relevant to the specific points I am making at the time. Further, I am often responding to the claims that are being made in the public domain. I do try to put them into perspective when I can – is this representative of the fringe, or the rank and file?

In the case of anti-GMO opinions, I have found that overwhelmingly those who are anti-GMO cite the same or a very similar list of standard claims, most of which are myths or misinformation.

Further, for those who are open to evidence, when the nature of such claims are pointed out to those who are trying to be skeptical, but still have an ideological opposition to GM, they often move the goalpost rather than change their position. They say, essentially, that – OK, maybe all of those reasons I cited for opposing GMO have turned out to be wrong, but I still don’t like big corporations having that much control over our food. Or they might fall back on the precautionary principle.

In other words, this is another strategy to avoid changing our position in the face of evidence, simply change the reasons for our position. This is similar to those who are ideologically opposed to the notion of global warming. First they claimed that the planet is not warming, then that it was but not human caused, then humans are contributing to warming but not that much, then, well, there’s nothing we can do about it anyway.

Humans have proven to be mentally nimble and inventive in the defense of our beliefs.

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