Glyphosate causes cancer? – large scientific study says no

Glyphosate causes cancer

One of the tropes of the pseudoscience world is that glyphosate causes cancer – but what does real science say? Well, numerous large epidemiological studies have yet to provide evidence of a link that would convince us that the herbicide has any link to any cancer.

Recently, another article in a prestigious cancer journal looked at thousands of  individuals exposed to glyphosate, and once again, have found no convincing evidence that glyphosate causes cancer. The totality of evidence, unless you are into glyphosate- and GMO-free cherry picking, continues to lead us to a simple conclusion – there is no link between the chemical and any of the 200 or more types of cancer.

One of the major issues with the tropes and myths about glyphosate is that many anti-science liberals tend to conflate glyphosate with genetically modified crops. This leads to a lot of unsupported hatred of GMO plants, despite the overwhelming scientific consensus that says that GMO agriculture is safe for humans, animals, and the environment – a consensus as broad and powerful as the one that states that climate change is caused by humans.

So let’s look at this new article, and how it fits into the narrative about glyphosate and cancer.

Continue reading “Glyphosate causes cancer? – large scientific study says no”

Glyphosate causes cancer? The IARC did not have all the evidence

glyphosate causes cancer

In 2015, the  International Agency for Research on Cancer (IARC) reviewed research data regarding Monsanto’s glyphosate weed killer, also known as RoundUp. The IARC, at that time, concluded that glyphosate causes cancer.

The IARC, one of the intergovernmental agencies within the World Health Organization, is widely respected for their research into the causes of cancer. And with respect to glyphosate, the IARC concluded that:

There was limited evidence in humans for the carcinogenicity of glyphosate. Case-control studies of occupational exposure in the USA, Canada, and Sweden reported increased risks for non-Hodgkin lymphoma that persisted after adjustment for other pesticides.

The AHS cohort did not show a signifi cantly increased risk of non-Hodgkin lymphoma. In male CD-1 mice, glyphosate induced a positive trend in the incidence of a rare tumour, renal tubule carcinoma.

A second study reported a positive trend for haemangiosarcoma in male mice. Glyphosate increased pancreatic islet-cell adenoma in male rats in two studies. A glyphosate formulation promoted skin tumours in an initiation-promotion study in mice. Glyphosate has been detected in the blood and urine of agricultural workers, indicating absorption.

Glyphosate and glyphosate formulations induced DNA and chromosomal damage in mammals, and in human and animal cells in vitro. One study reported increases in blood markers of chromosomal damage (micronuclei) in residents of several communities after spraying of glyphosate formulations.

The Working Group classified glyphosate as “probably carcinogenic to humans” (Group 2A).

When I looked at their conclusions from a couple of years ago, I argued that there was significant evidence that glyphosate was not correlated or causal to any of the 200 or so cancers. And I wasn’t alone in that assessment.


Glyphosate causes cancer – IARC lacked evidence

Unfortunately, when the IARC made its decision two years ago, there was one major problem. According to an extensive article by Kate Kelland in Reuters, one of the members of the IARC’s study group looking at glyphosate knew of recently published data that showed no link between the weed killer and cancer. Aaron Blair, an epidemiologist from the US National Cancer Institute, never mentioned this new data to the study group examining whether glyphosate causes cancer. So the IARC made its decision without all of the available evidence.

Reuters obtained information that lead it to state that:

Previously unreported court documents reviewed by Reuters from an ongoing U.S. legal case against Monsanto show that Blair knew the unpublished research found no evidence of a link between glyphosate and cancer. In a sworn deposition given in March this year in connection with the case, Blair also said the data would have altered IARC’s analysis. He said it would have made it less likely that glyphosate would meet the agency’s criteria for being classed as “probably carcinogenic.”

The IARC acts in a manner that it appears to develop a scientific consensus about what may increase the risks of cancer. As I have mentioned many times, the scientific consensus is a powerful tool in providing us with the collective conclusions of top scientists in a field. However, this consensus must be based on evidence, not opinion or belief. And if a consensus is “proclaimed” without consideration of all of the high quality evidence, then it’s hard to put much value in it.

Now there wasn’t a grand conspiracy that blocked the IARC from considering this new evidence. Blair himself was a senior researcher on the study that showed no link between cancer and glyphosate. The reason the research wasn’t included was simple – the IARC only uses published data to come to its consensus about cancer risk, and Blair’s research could not be included in the discussion. This leads to increased transparency and reduces the risk of claims of “secret evidence” that may lead to accusations of bias.

Now, this rule may seem onerous to some, it does keep the discussion to peer-reviewed data, ignoring data that hasn’t been vetted. This probably works both ways, leaving out data that may move a chemical into a cancer causing category or not.

But this decision by the IARC had some significant consequences. First, it’s hard to read anything about GMO foods, agriculture, or food without someone spouting off that “glyphosate causes cancer.” In fact, there’s a class action lawsuit in California, with 184 individual plaintiffs, who use the IARC analysis on glyphosate, claiming that exposure to the chemical gave them cancer. The plaintiffs allege Monsanto failed to warn consumers of the risks of RoundUp, which Monsanto fiercely denies.

Monsanto claims that the fresh data should have been published in time for use in IARC deliberations on glyphosate. Or, at the minimum, the preliminary data should have been evaluated, considering Blair’s involvement with both the IARC and the new research.

Again, according to Reuters,

The company also goes beyond saying the fresh data should have been published. It told Reuters the data was deliberately concealed by Blair, but provided no specific evidence of it being hidden.

So this gets a bit more troubling.

What did Aaron Blair do? And why?

This is what is troubling to me. Actually, the data that mostly refuted the hypothesis that glyphosate causes cancer was available two years before the IARC assessment meeting. Now, science does move slowly, but that’s glacial.

According to Blair, the data was not published in a timely manner because there was too much data to fit into one scientific paper (which seems like a lame excuse to this writer). Reuters actually asked whether “he deliberately did not publish it to avoid it being considered by IARC.” Of course, Blair denied it. Furthermore, the National Cancer Institute also stated that “space constraints” was one of the reasons why the new data on glyphosate was not published in a timely manner.

Of course, the absence of Blair’s data was a critical oversight – the IARC ended the meeting by concluding that the weed killer is a “probably human carcinogen.”

In fact, the statement based its findings on “limited evidence” of carcinogenicity in humans, but “sufficient evidence” in animal research models. It specifically stated that there was a “positive association” between glyphosate and non-Hodgkin lymphoma, a cancer of the blood.

Beyond the litigation mentioned above, the IARC had all kinds of negative consequences. For example, some countries have pending decisions regarding whether to relicense or ban sales of glyphosate. Some countries have even restricted glyphosate’s use in home gardens and on crops immediately prior to harvest.

And back to the class action lawsuit in California, Reuters reports that:

… (the) California judge took the IARC assessment into account in a separate legal case in March when ruling that the state can require RoundUp to carry a warning label that it may cause cancer. Monsanto is now facing further litigation from hundreds of plaintiffs across the United States who say glyphosate gave them or their loved ones non-Hodgkin lymphoma, citing the IARC assessment as part of their claims.

All, because of an apparently flawed decision without all of the high quality evidence considered. This is frustrating from a scientific standpoint.

What is in Blair’s study?

This unpublished research, and it’s still unpublished, came from the Agricultural Health Study, a large multi-center study led by scientists at the National Cancer Institute. The researchers examined agricultural workers and their families, in the USA, who were exposed to various agricultural chemicals, including glyphosate. Blair himself agreed that the unpublished data showed “no evidence of an association” between exposure to glyphosate and non-Hodgkin lymphoma.

In fact, a review by Acquavella et al., published in 2016, examined the body of research regarding glyphosate and non-Hodgkin lymphoma. The authors concluded that, “overall, our review did not find support in the epidemiologic literature for a causal association between glyphosate and non-Hodgkin lymphoma or multiple myeloma.” That’s a pretty powerful finding with regards to the IARC decision.

Additionally, Robert Tarone also published a paper in 2016 that took IARC’s decision regarding glyphosate to task. He concluded that,

It is shown that the classification of glyphosate as a probable human carcinogen was the result of a flawed and incomplete summary of the experimental evidence evaluated by the Working Group. Rational and effective cancer prevention activities depend on scientifically sound and unbiased assessments of the carcinogenic potential of suspected agents. Implications of the erroneous classification of glyphosate with respect to the IARC Monograph Working Group deliberative process are discussed.

The IARC’s decision that glyphosate causes cancer seems to be under attack by serious researchers.

Blair admitted, while being deposed by Monsanto lawyers, that IARC’s review of whether glyphosate causes cancer would have been different if the Agricultural Health Study data were included. According to Blair, the addition of the missing data would have  “driven the meta-relative risk downward.” In non-scientific terms, that means meta-data would have shown a reduced correlation between glyphosate and non-Hodgkin lymphoma.

Essentially, the IARC review ignored a huge body of robust data from a comprehensive study on exposure to glyphosate, and it’s relationship to cancers. This is a major oversight of the IARC decision.

And it’s just shocking to note that one person, Aaron Blair, was on the IARC review committee and had insider access to high quality data that refuted the IARC’s claims of correlation (and causation) between glyphosate and cancer.

Reuters took the data (which, as I stated, still has not been published, although the NCI told Reuters that they are currently working on an updated analysis) to two statistical experts to determine what it may say about whether glyphosate causes cancer. Neither of the experts had seen the data, and neither had a conflict of interest with respect to glyphosate or Monsanto.

The experts came to two key conclusions after examining the data:

  1. There was “no apparent scientific preseason for not publishing the data” from the large study. In other words, absent some issue like bias or bad study design, they felt that the data was publishable in its current form.
  2. The data shows no evidence that glyphosate causes cancer, especially non-Hodgkins lymphoma.

Of course, you’d think that the IARC would reconsider it’s decision about glyphosate, relying upon all the science, not just what they had already decided. Apparently, that’s not going to happen.

Reuters wrote to the IARC about Blair’s new data and whether they would reconsider their position. They responded by email,

IARC declined to say whether Blair informed IARC staff about the unpublished data, whether he should have, and whether that data might have changed IARC’s evaluation of glyphosate had it been published in time. The agency said it had no plans to reconsider its assessment of the chemical.

That’s not very scientific. The consensus must change with new, high quality data. It seems like the IARC is being stubborn about their decision rather than looking at more robust evidence that contradicts their conclusions.


Glyphosate causes cancer – the Summary

As I wrote in 2015, without the data from the Agricultural Health study, I, and other researchers, felt that the IARC decision was suspect. It seemed to rely upon very weak associations between glyphosate and non-Hodgkin lymphoma, while ignoring high quality evidence that showed no correlation.

With this data, as yet unpublished, the IARC’s decision about the carcinogenicity of glyphosate just doesn’t pass scientific credibility.

I hope that when Blair’s study finally gets published, the IARC will review its findings and follow the science to a more defensible conclusion. What should trouble the IARC is that many scientists are starting to look askance at their decisions regarding carcinogens. The evidence just doesn’t support their conclusions on glyphosate, but what if their decisions about other chemicals is also this badly done?

I’m convinced that we overstate the risk of cancers for lots of reasons. But there are really only a handful of ways to prevent cancer – avoiding glyphosate isn’t one of them.

Glyphosate causes cancer? The body of scientific evidence seems to say no.

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Monsanto glyphosate causes cancer – so do apples

Monsanto glyphosate

Monsanto glyphosate (Roundup)  is a broad-spectrum systemic herbicide used to kill weeds, especially annual broadleaf weeds and grasses that are known to compete with commercial crops grown around the world. It has several advantages over many herbicides in that it breaks down in the soil into non-toxic organic molecules, reducing or eliminating contamination of groundwater and lower soils.

Monsanto has developed genetically modified (GMO) grains that are resistant to glyphosate, so that agriculture can apply the herbicide to kill the competitive weeds while not harming the crop. This allows farmers to suppress the weeds while allowing better production out of the grain crop.

Whatever the benefits of Monsanto glyphosate, GMOs and the herbicide are tied together in many minds. And there has been an ongoing effort by many people to claim that glyphosate causes cancer. But let’s look at the science, because maybe we’ll get some information.

Continue reading “Monsanto glyphosate causes cancer – so do apples”

GMO crop pesticide use in USA soybeans and corn – just the facts

GMO crop pesticide

The safety of GMO crops to humans, animals and the environment has been well established. The scientific consensus clearly states that consuming bioengineered foods has no effect on your health. Clearly, you can grab an ear of GMO corn, put some butter and a sprinkle of salt on it, and you will eat it with no negative health effects. And you’ll have a giant smile across your face.

But the anti-GMO forces have attempted to move the target. They have tried to claim that GMO crops are less productive and cost more to produce. That’s beyond the scope of this article, though there is some pretty good evidence that there is higher yield for bioengineered crops.

One of the more annoying aspects of the anti-GMO complains is conflating the genetically modified crop with the GMO crop pesticide. Invariably, some someone will post a meme or discuss a trope that evolves from GMO food to glyphosate, the herbicide known as RoundUp. the conversation will lead to ridiculous conclusions that Monsanto (who manufactures glyphosate) is killing everyone by forcing farmers to use RoundUp with Monsanto’s own GMO crops which are resistant to glyphosate. It’s all Monsanto all the time when discussing GMO crop pesticide use.

A new paper was published last month that may or may not give us more information about pesticide use with GMO crops.

Continue reading “GMO crop pesticide use in USA soybeans and corn – just the facts”

Dr. Oz falls for the overhyped and debunked GMO corn study

dr. oz

A few weeks ago, Gilles-Eric Séralini and his homeopathy loving coauthor published an article in Food and Chemical Toxicology that concluded that glyphosate (known as Roundup)-resistant NK603 GMO corn, developed by Monsanto, causes severe diseases such as tumors in rats. And usual anti-science websites bought into this nonsense, including the TV medical practitioner, Dr. Oz.

It’s time to remind everyone that the Séralini study was bogus, and that Dr. Oz is also bogus. Here we go.

Continue reading “Dr. Oz falls for the overhyped and debunked GMO corn study”

Séralini’s controversial GMOs cause cancer article retracted

GMOs cause cancer

In 2012, the interwebs exploded because of an article (pdf) published in Food and Chemical Toxicology by Gilles-Eric Séralini et al. that attempted to show that GMOs cause cancer in rats fed genetically modified corn which is resistant to the herbicide Roundup. They also found similar health problems in rats fed the herbicide alone (along with non-GM feed). The rodents experienced hormone imbalances, along with more and larger mammary tumors, earlier in life, than rats fed a non-GM diet. The authors claimed that the GM- or pesticide-fed rats also died earlier.

Séralini et al. stated that this is the first time GMO corn has been tested for toxicity throughout a rat’s lifespan even though this type of GM corn accounts for more than half of the US crop.

Séralini’s article could have been an important part of the discourse regarding the safety of GMOs – except for a few important problems. Scientists across the world criticized the study for its bad study design, bad statistics, and overhyping of the results.

I personally found the study lacking in basic toxicology methodology, like providing us with dose-response studies, that show us at what level of consumption of the GMO corn would have an effect (if there is one). Of course, Séralini used so few rats in his “study” that it would have been difficult if not possible to develop a dose response.

Continue reading “Séralini’s controversial GMOs cause cancer article retracted”

Simple math – the dose makes the poison

If you spend any amount of time on the internet researching science and pseudoscience, you’ll find alarming claims about toxic or poisonous substances in our foods, vaccines, air, water, and so much else. And then you’ll find a lot of people (myself included) who try to present science-based evidence that these substances are neither toxic nor poisonous.

Generally, the pseudoscience argument proceeds along the lines of “this unpronounceable chemical is going to cause cancer.” And the science (read scientific skeptic) side says “wrong!” Or something like that.

Paracelsus, a 16th century Swiss German physician, alchemist, astrologer, is traditionally thought to have founded the discipline of toxicology, an important branch of medicine, physiology, and pharmacology. Paracelsus wrote one of the most important principles of toxicology:

All things are poisons, for there is nothing without poisonous qualities. It is only the dose which makes a thing poison.

In other words, if you’re speaking about substances in foods or vaccines or anything, the most important principle is that the dose makes the poison (or toxin). Everything that we can consume or breathe is potentially toxic, but what is the most overriding principle must be the dose. Continue reading “Simple math – the dose makes the poison”

Refusers misuse GMO rice research data

Scientific American blared a headline that “Genetically Modified Crops Pass Benefits to Weeds,” which claimed that the results of a study of GMO rice indicated that the rice might pass certain genetic information to “weeds,” which will then get an unintended biological fitness increase. They stated that the GMO rice could pass bioengineered genes from the GMO rice to the weeds.

The underlying peer-reviewed article, trumpeted by Scientific American, may not say what they think it says. In fact, in my review (below), I’m not sure it was very well done.

Continue reading “Refusers misuse GMO rice research data”

Arguments that GMO opponents should delete from their brains

keep-calm-gmo-safe-1From my perspective as a trained scientist, skeptic and observer of political debates, there are four scientific issues that have wandered into the realm of political debate: evolution, climate change, vaccines and genetically modified organisms (GMOs) generally with regards to food and agriculture.

Evolution and human caused climate change (or sometimes called anthropogenic global warming, AGW) are scientific facts supported by literally mountains of data. The arguments presented by evolution deniers is easily refuted. And the myths pushed by global warming deniers are also quickly debunked. Both of these have become a part of the political conversation, with the evolution and climate change deniers being almost exclusively made up of conservative political groups, including Republicans in the USA. There is no debate about these two facts from a scientific point of view, unless someone cherry picks scientifically weak papers published in bad journals to confirm a bias against these scientific facts.

Vaccines aren’t really a scientific principle per se, but the support for the safety and effectiveness of vaccines is pretty much settled by the vast majority of scientists who actually have experience, research and education in the key fields of science related to vaccines, such as epidemiology, immunology, microbiology, virology, etc. etc. The fact that about 95% of children in developed countries (including the USA and most of Europe) indicates that there isn’t even a “political debate” except some blathering and noise from a tiny lunatic fringe. And the 5% of children who aren’t vaccinated don’t exclusively represent active vaccine deniers–most of these unvaccinated children either cannot be immunized for some health reason, have procrastinating parents, or have parents who may be too poor to get their children vaccinated, even if it’s free to most people in developed countries. The only reason most of us get worked up about the approximately 1-2% of parents who actively resist vaccines is because we think all children should be protected from vaccine-preventable diseases.

On the other hand, GMOs, at some levels, should have some level of public discourse and debate. For example, glyphosate (Monsanto’s RoundUp) resistant crops have raised public concerns, and despite some awful scientific evidence that has been solidly ridiculed in the scientific community, along with solid scientific studies that show no correlation (let alone causation) between human health and glyphosate exposure (see this, this, and this), excessive use of pesticides frighten people.

Personally, I can buy into certain arguments against GMOs. For example, I think that monoculture agriculture is extremely susceptible to an introduced or novel pest, which could be devastating to our food supply. I am also concerned about certain unintended consequences such as evolved pest resistance (but then again this has been a war since the first day genetic modification occurred 10,000 years ago), lower crop productivity, or other issues. So far, science hasn’t uncovered any problems so far, so there’s that.

If the anti-GMO environmentalist community wants to engage in a reasoned conversation about GMOs with those of us who have scientific evidence supporting our discussion points, then they have to quit using five bad arguments, which they seem to pull out of the manual of science deniers everywhere. Because anti-GMO arguments use the same ridiculous “debate” strategies as those who deny vaccines, evolution and climate change. As I’ve joked more times than I care to remember, I feel as all the science deniers attend the same convention to discuss tactics and strategies. It seems ironic to me that those who are anti-GMO make the same exact points as the climate change deniers, yet those two groups have nothing in common except they are both humans.

So what are these five bad arguments? Glad you asked, so here we go. Continue reading “Arguments that GMO opponents should delete from their brains”

Anti-GMO cult trumpets GMO genes transfer to wild rice–update

GMO_riceIt is well accepted observation that when the pseudoscience or anti-science crowd runs out of supporting evidence (usually when it’s thoroughly debunked by scientific skeptics), it has to rely upon the whole range of logical fallacies, which are errors in reasoning to support a position in an argument or debate. Because scientific skeptics (or if we’re talking about medicine, science based medicine) always demand high quality evidence to support their own claims, or alternatively demanding evidence from other making suspicious claims, the anti-science and pseudoscience pushing troupes frequently cherry pick “peer-reviewed” research to use as their “proof” for their claims. 

Cherry picking makes it appear that there a nothing but ripe beautiful cherries of evidence supporting your position. The problem is when you look at the whole basket of cherry’s you see all sorts quality. Same with peer-reviewed evidence. You may find one article that says “Point A is correct.” But what is the quality of that article? How does it fit with all the other articles that say “Point A is not only incorrect, but Conclusion B is the scientific consensus.” You can’t cherry pick one article, without understanding and analyzing the vast breadth of research in a field.

Moreover, because the pseudoscience promoters are resort to confirmation bias, always looking for evidence to support their beliefs rather than seeing what the evidence supports, they ignore the vast majority of evidence or tend to misinterpret the evidence. So, when you read some blog post or pseudo-news article about a published scientific article that says GMO’s are dangerous, you need to dig beyond the headlines, and head right to the scientific source to determine what is really being said. And this happened recently. Continue reading “Anti-GMO cult trumpets GMO genes transfer to wild rice–update”