GMOs cause leukemia!? Think again.

Swiss albino mouse by Rick via Flickr.

The Organic Consumers Association (among others) has gleefully announced: New Study Links GMO Food To Leukemia (also saved as a PDF). This article by Sayer Ji was originally published on Green Med Info on 12 May 2013. The paper is Hematotoxicity of Bacillus thuringiensis as Spore-crystal Strains Cry1Aa, Cry1Ab, Cry1Ac or Cry2Aa in Swiss Albino Mice by Mezzomo et al, published first in November 2012 then again in March 2013 (more on that later).
The article states: “Bt toxins are capable of targeting mammalian cells, particularly the erythroid (red blood cell) lineage, resulting in red blood cell changes indicative of significant damage, such as anemia. In addition, the study found that Bt toxins suppressed bone marrow proliferation creating abnormal lymphocyte patterns consistent with some types of leukemia.”
Except, the article doesn’t actually say that at all. I have a few quick observations, then a rebuttal provided by our own Dr. David Tribe, and I wrap up this latest edition of whack-a-mole with a revelation. There’s a lot more to say about this paper, and hopefully we will learn more as time goes by, but this post is just a fast attempt to help people know that this is not a good paper to be pointing at.

Are organic Bt sprays dangerous?

The strangest thing about the rush by OCA and other anti-GMO folks to call this the latest “GMO” scandal is that the study didn’t test Bt toxins expressed by biotech crops. It didn’t even test the Bt toxins expressed in bacteria then purified. Instead, the paper says they used “spore-crystals Cry1Aa, Cry1Ab, Cry1Ac and Cry2Aa from B. thuringiensis var. kurstaki were obtained in lyophilized form”. Some Bacillus thuringiensis bacteria can go dormant, forming a spore, and form crystals around the outside of the bacteria to protect themselves.
In other words, this study used the whole bacteria – the exact same thing that is used in organic Bt sprays. According to Organic Consumers Association, Bt sprays are used by “at least 57 percent of organic farmers” and “does not have detrimental effects on mammals, birds or non-target insect species and microorganisms. In addition, Bt sprays leave no poisonous residue on crops or trees and are readily degraded into the environment.” Yet somehow the exact same active ingredient, when expressed in a transgenic plant, lasts a long time in the environment and is now toxic to everything, according to OCA et al (despite the pesky science that says it doesn’t).
Anyway, the authors resuspended the whole bacteria in water, then orally administered them to the mice in incredibly high concentrations: 27, 136, and 270 mg of bacteria per kg of body weight.
The most important thing that sticks out to me here is that there could be all sorts of other things about the bacteria besides the presence of the Bt toxin that could be affecting the mice. Since the negative control was water instead of culture medium with Bt bacteria that don’t express the toxin, we have no idea what it is in the solution that might have affected the mice.
Strangely, they never mention this and while they are careful to conclude “results showed that the Bt spore-crystals… can cause some hematological risks to vertebrates” rather than saying it was the Bt crystals themselves, they then conclude there is “increased risk of human and animal exposures to significant levels of these toxins, especially through diet”.
So, I have to wonder – are the authors worried about organic farming? To reiterate, genetically engineered plants have only the Bt toxin, not the whole bacteria, while organic farmers use the whole bacteria as a spray. Realistically the dose of “spore-crystals” from a Bt spray residue is much lower than what these researchers claim harm from, but still. According to the Pesticide Information Profile published by Cornell, Bt sprays show every indication of being safe (and so do Bt toxins themselves).

David Tribe’s Analysis

David Tribe wrote a great but short analysis over at Reddit and I wanted to make sure more people were able to see it:

  • They used spore/crystals from modified Bt strains, rather than isolated protein. As per Schnepf, 2012a, such sporulating cultures are about ~20% Bt crystal proteins by dry weight. In other words, 80% of what the mice were fed is God knows what.
  • The results seen are not due to use of too high a level of protein (270 mg/kg) , as there are reports of up to 5280 mg/kg of purified proteins fed to mice without any adverse effects (Schnepf, 2012b)


  1. The real negative control should have been wild type Bt strains, not water, as water lacks the other stuff floating around the culture medium
  2. The amounts fed the mice do not reflect human dietary levels– they were some ~ 106 to 108 time higher than exposure from GM or organic crops ( as per Hammond, 2012)
  3. The use of 3 mice/sex/group, as compared to OECD standards that call for 5 mice per sex per group.
  4. The historical incidence for these pathologies in the mice used was not reported. Thus, it is not clear if they are looking at treatment effects or natural biological variability for the mice
  5. The results did not all show the expected dose-response, with the lower dose resulting in the highest symptoms, as opposed to the other way around (eg, the 136 Cry1Ab had reduced MCH, but not the 270 mg/kg group)
  6. The reduction in MCV and RDW in all groups suggests a contaminant is involved rather than different Bt proteins
  7. For dose response, they get U shaped or inverse U shaped curves, a la Seralini. These could be a result of small animal numbers, not of hormesis.
  8. In the lit review, they say that Thomas and Ellar (1983) previously showed that cry proteins were hemolytic. However, Thomas and Ellar (1983) tested cyt proteins, not cry proteins. Even then, the cyt results were in vitro– there were no results when mice were fed the cyt proteins, presumably because they are digested.
  9. They also cite Aris and LeBlanc (Bt in mother and fetal blood) to support their work. (a rubbish paper)
  10. Their results are at odds with all the other studies whereby Bt (the bacterium) and cry (the bt protein) have not had adverse results in feeding studies.

Also — the journal is not a high quality journal.


I think we’ve established that this paper has some methodological issues. It’s not just us, though. The paper was originally published in Food Chem Toxicol, a generally reliable journal that has been around since 1982, and then withdrawn. Surely there is another story about that – Why was it published in the first place? Why was it withdrawn? Who requested the withdrawal? But the point is that the study as currently published is not in a “high quality journal”, as David puts it.
The Journal of Hematology & Thromboembolic Diseases is brand new, without any impact factor or history of quality to support it. This study appeared in issue 1, volume 1. The National Library of Medicine reviews scientific journals based on their scientific merit, strength of their review process, etc for inclusion in PubMed. OMICS, the parent company for this journal, is pointedly not indexed in PubMed, and has been dubbed “fake journals” by many scientists.
Why does the journal matter? High quality journals have a high quality review process. They seek out reviewers with the relevant expertise to do a proper science-based review of the methods, results, and conclusions. Low quality journals, simply put, do not.
Finally, I will end with a note from Karl Haro von Mogel, who is currently looking a little deeper into this paper’s curious history: “There’s something going on here that matters to everyone who cares about the peer review process that we depend upon to sift reliable studies from specious claims. Paired with rapid amplification through political advocacy, the reputation of science is at risk of being hijacked to obscure the truth.”


  1. The original paper was obviously withdrawn because Monsanto threatened the journal. Duh.
    Seriously, so typical. The sad part is, google “GMO” and “Leukemia” and see how many websites have picked up on this as definitive research.
    I watched Genetic Roulette last night and laughed, cried and puked at the same time.

  2. This group of scientists tried to publish this study in another journal (Food and Chemical Toxicology), but it was withdrawn. The PDF you linked is when they re-submitted their study to a different journal (Journal of Hematology & Thromboembolic Diseases). These are not the highest quality journals out there so I’m skeptical and especially curious as to why it was withdrawn from Food and Chemical Toxicology. It’s sort of reminds me of how when you apply to college, you apply to a few “safety schools”, just in case you don’t get in to the ones you were hoping to get in to.
    Here’s an article from a few weeks ago basically reiterating what I just said:

  3. This is what’s really troubling to me:

    rapid amplification through political advocacy

    And it’s funny because it is completely parallel to the situation bemoaned by Mother Jones on other science issues and conspiracy theory some time ago:
    How to Make Your Lie Go Mainstream in 26 Easy Steps
    And they don’t see themselves in the mirror. It’s baffling.

  4. From 1989 to 1996 I worked for a company called Mycogen that produced Bt insecticides. Some were in the original Bacillus strains and some were in “genetically engineered” Pseudomonas florescens (CellCap(r)) All the batches from the fermenters had to be checked for exotoxin – something that Bt can make that is actually rather nasty. Of course there was much more risk of that from the Bacillus fermentation than from the Pseudomonas.
    This study is absurd in many ways. Organic and Biotech have this very deep connection with Bt. The biotech version is much less complicated.

  5. I believe the original article is misquoted. The article says LEUKOgenic, causing an increase in white cell count, not LeukeMOgenic (causing leukemia). Any inflammation or stress can increase white cell count.
    2 letters make a big difference.
    Dan Goldstein (Monsanto)

  6. Thanks for pointing that out. I was wondering how the claim that GMOs were causing leukemia came about. I read the paper and saw nothing about blood cancer.

  7. So I was reading another piece today and saw the name Sayer Ji. I was trying to remember where I had also seen that name today, and it was here in this post. I think I’m seeing a pattern.
    Angelina Jolie, radical strategies for cancer prevention, and genetics denialism

    Sadly, Adams is not alone in his ignorance of oncology. There’s also Sayer Ji, who claimed that vaccines are “transhumanism” that subverts evolution and made one of the most spectacularly clueless arguments against evidence-based medicine I’ve ever seen, dismissing it as a “coin flip.”

    And oddly this all wraps back to the genetic denialism we saw before, summarized by Mary Carmichael a couple of years back: DNA, Denial, and the Rise of “Environmental Determinism.
    It’s a bizarre theory–that genes don’t have any impact on human health, while they are crazy effective when they are launched from plants. Or something.

  8. Reiterating what Karl has said. It seems to be getting standard where a paper is published when on all accounts it appears it should not have been. The public is relying on and paying for ‘beyond reproach’, valid science research. We can’t go around whining about how ‘good’ science journalism is dying when we can’t trust the messengers. And blaming it on the ‘low quality’ journal doesn’t cut it, because, even the so called prestigious journals get it wrong. If this research is as bad as it sounds. What does that say about the credentials of the research team behind it? Or is the real issue too much corporate funded research?

  9. For the record I support all the comments sourced to me in the above post, as they are all supported by the claims in the original paper, but they were originally supplied by me in what I thought was a private comment (not sure where at the moment — probably email), and would like to make it clear that I relied heavily analysis by another person in providing them. I am glad they are now circulating widely, but don’t claim original thinking. But I have reached the same conclusions from the facts provided in the paper.

  10. I am actually tired of this “war” of gmo pros and cons (and I mean people). It irks me to see articles like this – reason for that is that you cannot guarantee safety of gmos. Yet, you will do your part in discrediting any doubt that might arise.
    Consumers are angry for a reason. They know Monsanto politics and its history. They want a choice in their food supply. This country’s history has taught people to have a say, to have a right to choose, and to express their concerns. Monsanto and the like are trying to shut us up and force their products on us. We do not like that and it’s not going to pass. No matter how many former Monsanto employees are a part of FDA team!

  11. So sorry, David! These comments were on a public website (I don’t even have a Reddit account so I wasn’t logged in) but I still should have asked. I moved too fast in my hurry to attempt to dispel the claims made about this paper. Just to be clear, are these not your comments? How can I correct this so it is accurate? If you have additional comments or edits I would be happy to make changes.

  12. Where are the politics in this post? I am questioning the methods and conclusions of the paper. If they have proven anything, they have proven that organic Bt spray may be harmful if someone drank it. The study isn’t even about GMOs. If you want a choice to avoid the potentially dangerous substance here, don’t drink pesticide. If you’re convinced this study shows such reason for concern that even resides should be avoided, don’t buy organic. However, there have been many studies on Bt bacteria that show it to be safe when used at reasonable doses.
    No one can prove the absolute safety of anything, especially since safety is so dependent on dose. Virtually everything is toxic at a high enough dose. The best we can do is find what doses are toxic, and what doses are safe. Then divide the safe level by an additional factor of 10 or 100 so even the sickest most vulnerable people are protected. That’s the standard, all over the world.
    Finally, who is forcing you to buy anything? There are so many choices in the grocery store that it can be overwhelming. And you don’t even have to go to the grocery store! You can choose farmer’s markets, CSAs, direct shipments, etc. Or you can grow your own! Move to the country and raise some goats, whatever you like!

  13. David,
    The person in question posted them to a thread on this topic on the Reddit r/GMOFacts subreddit saying they had emailed you and these were in your response. I ran across them there and posted them to Twitter with @geneticmaize tagged. I was interested in them because they gave more substance than the “retracted” story line. Is there a better source for the criticisms?

  14. Bill,
    There’s no problem, I’m just trying to not misrepresent the source, and set the record straight. Give me as the source– but it is not completely my own effort.

  15. No problem, Anastasia. Ill go in and make a minor two word “then a rebuttal ” provided by our own” edit that makes me comfortable.

  16. Pro Nature,
    Maybe you could point out to us why you think the research IS scientifically valid and which conclusions lead you to believe specifically that it shows GMO’s cause Leukaemia?
    Would you say 3 replicate mice per group is enough?
    Do you think using water as a control is sufficient to prove it is definitely the Bt crystals that are affecting the mice?
    In the meantime I’d be putting your energies into lobbying Organic growers to stop using Bt sprays. After all they are the people pushing this turd of a paper as good science.

  17. Of course. So, not only is Monsanto in bed with powerful politicians but now they’re threatening highly reliable journals!
    Is that a spy Monsanto satellite I hear above? Quick get your tinfoil hats!!

  18. Andrew, it’s fact, Monsanto threatened legal action. And they do have tons of money in lobbyists… You’re trying to refute things that Monsanto wouldn’t even refute.

  19. The scientific community is politically inept.
    Monsanto seeds only go out when a 47-page license agreement is signed, specifying what they can and cannot be used for, disallowing scientific study. You cannot own a Monsanto seed – you can only license the use of it for a specific purpose.
    The lack of study with Monsanto seed is the real crime of our day, and it’s a great way to control what “scientists” have to say about it. One might think with 240 million acres of Monsanto Bt and RoundupReady crops out there, things might be different?

  20. This is an old thread (which must have escaped me at that time), but Frank just linked it on Twitter and that’s why I saw it now. To add to the observation that “OMICS, the parent company for this journal, is pointedly not indexed in PubMed, and has been dubbed ‘fake journals’ by many scientists.” There is a librarian at the University of Colorado, Jeffrey Beall, who maintains a list of “predatory” publishers, which includes the OMICS Group:
    Following a list of pre-established criteria[1] Beall determines whether a publisher is “predatory” (i.e. mostly because they offer to publish a paper in their seemingly academic journals simply for money and without proper peer-review, editing, etc.)
    Beall’s List has already been discussed or mentioned in Nature[2] and Science[3], and apart from publishing his criteria he also gives publishers the possibility to appeal against his decision[4], i.e. this is a very trustworthy and rigorous process, even if it is nothing “official.”
    What this indicates, though, is that the article may not even qualify as a peer-reviewed, scientific publication; it’s more like self-publishing: You pay a publisher and they print whatever you want to have printed…
    I’ve made it a custom to check Beall’s list whenever I come across an article that is strange (be it the content, language or layout), and more often than not I find the respective “journal”[5] or publisher[6] on his list.

  21. A friend asked me about this study recently (pointed him to this thread!) and while googling around, I discovered that some believe Monsanto “mysteriously” caused the paper to be withdrawn from FCT! See here (tried to add a rel=”nofollow” to that link since it’s to “independent science news”). I really, really wish journal publishers would say why papers are withdrawn / retracted, since that would make these kinds of conspiracies be less believable. 🙁

  22. Humans and animals cannot control the air they breathe, Anastasia. I too am weary from the GMO debate, but at this point, there is no escape. Our governments and big agri have decided to spray BT EVERYWHERE, in the suburbs,farms, in our forests, and preserves. I totally understand they feel this is a safer alternative than chemical pesticides, but we all know there is collateral damage to other insect species when you do the research.
    A Canadian study demonstrated spores were detected in the nasal passages of Canadian citizens days and weeks after spraying Bt. It only takes a few sniffs and a swallow to ingest more Bt than one would ever consume from well washed organic foods over a lifetime.
    After ingesting Bt (which loves our alkaline intestines)…yes, our stomach acid may break down the bacteria, but for many stressed citizens and people who dilute their stomach acid with liquids, infection potential is present.
    “B cereus infections” are on the rise and according to what I have read, in no way are doctors screening patients for Bt infections. Even so, it is difficult to detect the difference between B. cereus and B. thuringiensis in the lab. And they simply are not SCREENING for Bt infections!
    Bt is found naturally in our soil BUT only in SMALL amounts. There is such a thing as flora BALANCE in soil as well as in animal guts. You simply can not start spraying Bt everywhere and not expect to upset the balance of nature. As a scientist you should understand that ingesting too much water can KILL YOU…And Bt is a spore, capable of surviving under harsh conditions even with exposure from rain and UV…and in spite of what scientist (paid by big agri) want the ignorant public to believe we are heavily exposed to Bt and cry proteins from GMOs.
    When doctors and scientists can’t explain the etiology of booming rates of infertility, autism, Alzheimer disease, irritable bowel syndromes, chronic fatigue, fibromyalgia, then my “theory” is the introduction of GMOs and overuse of Bt (never tested long term on humans)are triggers.
    We were told for decades that DTT was safe and for over half a century by big tobacco that smoking was perfectly fine and caused no problems. Bt and GMOs will go down the same road, sadly, with tremendous collateral damage to the eco system and all wildlife, including ignorant humans and those with major hubris.
    Editor’s note: personal attacks and inflammatory language removed.

  23. For those saying we deserve a choice we do have a choice. If you want to avoid GMO’s buy Organic. Now, I think GMO’s have a monopoly over the food industry right now in America. A lot of people can’t afford organic food and are forced to eat GMO’s. The problem is how expensive Organic food is. If Organic farmers got the same government subsidies as conventional farmers the price of organic food would go way down. Now, If you want my opinion on GMO’s I would say the way we are implementing this technology is extremly irresponsible. Currently the United States USDA or FDA does not require any safety tests on GMO’s. Safety test results are optional. All they require is a word of mouth from Monsanto saying that we find this product safe. Now, Here are the dangers that aren’t being talked about.
    For one, the validity of GMO’s are based on an outdated theory called the one gene one protein hypothesis. The hypothesis states that one gene codes for only one protein. This was disproved during the human genome project back in 2002. We now know that any gene can give more than one good or bad protein. As we keep changing the genes ultimately potentially dangerous proteins also known as “rogue” proteins will be produced. That is why some say GMO’s are bringing on a huge increase in food allergies. It’s impossible to know for sure though because as you know, their is no GMO labeling in the United States and in turn no way to track these statistics.
    GMO’s are also based on an understanding that genes cannot survive the human digestive system. We now know that genes can pass on through our digestive system into bacteria in our gut. antibiotic marker genes (explained in the video below) can enter bacteria in our gut and has the potential to multiply. Some believe that it is increasing our resistance to antibiotics.
    Almost the whole world has GMO labeling except the United States. United States just so happens to be the biggest producer of GMO’s. Go Figure. I think it is reasonable to say people like me are not anti science. We are simply for responcible science.
    Here is the video I was talking about. Jeffery Smith over at the “Institute for Responsible Technology” explains the huge difference between A genetically modified crop and a natural crop. He also explains the potential dangers that aren’t being brought up by the American scientific community. Hopefully by spreading awareness of this issue we will give scientists the courage to speak up.

  24. Oh dear ! and to think in Africa instead of maximizing on the land resources and eat fresh produce we run and import GMOs ! Even Us!

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