Toxicologist pans glyphosate report

‘They (IARC) got this totally wrong,’ says Canadian pesticide researcher Keith Solomon

A Canadian toxicologist says the World Health Organization made a critical scientific error in its decision to classify glyphosate as a probable carcinogen.

A panel of experts with the WHO’s International Agency for Research (IARC) on Cancer released a report March 20 on five pesticides, including glyphosate, the most widely used pesticide in the world.

After reviewing the scientific literature, the experts classified glyphosate, which is the active ingredient in Roundup, as Group 2A: probably carcinogenic to humans.

In a brief statement explaining the new designation, the scientists cited a number of research papers, such as a study on rural Colombians who were exposed to a spray of Roundup.

IARC said the study demonstrated that glyphosate can cause genotoxicity, or DNA damage, and cause cellular mutations that may result in cancer.

“One study (of) community residents reported increases in blood markers of chromosomal damage (micronuclei) after glyphosate formulations were sprayed nearby,” the report said.

Keith Solomon, a University of Guelph professor emeritus and a globally recognized authority on pesticides, said the conclusion is “totally wrong.”

Solomon wrote the Colombian study.

“They stated there was evidence of genotoxicity and they quoted one paper to support that statement,” Solomon said.


“There’s no evidence that glyphosate is genotoxic.”

Solomon and an international team of scientists conducted a study on glyphosate in Colombia in the early 2000s as part of a Colombian government program to destroy illegal coca fields in the countryside.

Coca is used to produce cocaine.

Solomon and his colleagues were asked to do a risk assessment of the human health and environmental risks associated with the coca eradication program.

The scientists took blood samples from Colombian volunteers who were exposed to glyphosate when government planes sprayed coca fields.

To assess the likelihood of DNA damage, they tested for the presence of “genotoxicity biomarkers” in the volunteers’ blood, known as micronuclei.

“All we were interested in was, does the spraying of the coca cause increased micronuclei,” Solomon said.

The scientists took blood samples four months later because that’s approximately how long it would take to replace the white blood cells exposed to glyphosate. Solomon and his team then compared the results to a group of rural residents who weren’t exposed to the airplane spray.


“When we looked at the differences in the micronuclei between those two groups, we found no difference,” he said.

“They (IARC) got this totally wrong. They said the study showed there was a relationship…. It’s certainly a different conclusion than the one we came to.”

Solomon isn’t the only scientist to speak out against the IARC decision. A number of toxicologists and pesticide experts have criticized the United Nations agency for a lack of balance.

They said the report ignored an abundance of papers showing that glyphosate is not carcinogenic. Instead, it focused on a few marginal studies showing that glyphosate promotes tumours in mice and epidemiological studies linking the herbicide to non-Hodgkin’s lymphoma.

Aaron Blair, a scientist emeritus at the National Cancer Institute who led the IARC group of 17 experts, told Reuters that the classification is scientifically appropriate.

He said there might be hundreds of studies on glyphosate, but concerns about the herbicide are mounting.

“We looked at, ‘is there evidence that glyphosate causes cancer?’ and the answer is ‘probably.’ That is different than yes.”

Solomon said the conclusion contradicts scientific consensus. National regulatory agencies around the globe have evaluated glyphosate and concluded the weed killer is not a human health risk. As an example, a recent German report concluded that glyphosate is probably not a carcinogen.


Solomon said he would reserve final judgment until IARC publishes a comprehensive report on its decision, which will be released in about a year.

  • old-dog

    Why did Health Canada increase the allowable limits of glyphosate on our food?
    Why did the Canadian Government give Monsanto a “GET OUT OF COURT FREE CARD”?
    Who is looking at the whole picture, the effect that glyphosate and other pesticides are having on the largest living organism the soil we stand on?
    Why do we need more cancer clinics?
    At the rate we are going we will not have to worry about over population!!!

    • Ian Brown

      Wait a second???? What do you mean Canadian Government gave Monsanto a get out of jail free card!!??

  • Dr

    Boy they all sure get up in arms about possible carcinogen status. When a group or individual gets so defensive about a possible cancer cause maybe we should all look deeper. Our mothers knew how to bring out the half truths, the unsaid and the outright lies. She also often asked me where I thought dishonesty would get me.

    Growth chambers in the basements of higher learning establishments, scientists working on similar projects patting each other on the back, 19 lawyers to Percy Schmeisers 1, monoculture on a massive scale, CEOs and presidents of major chemical companies moving between their chemical companies and top positions at the USDA. How ridiculously stupid do they think the rest of the population is? The questioning started to be serious when Food Inc the documentary came out.
    The house of cards is teetering , if they even admit one aspect is wrong it all comes crashing down . It is pathetic what big corporate money and greed does to people. Rather than work together and say , you have a point there, perhaps we could do a side by side study or work at solving these huge world problem together …but NO! Let’s show the youth how to take runs at the WHO and each other and while we are at it lets degrade and discredit other groups that think differently than our narrow way of thinking.

    Come on Monsanto and minions time to stop declining interviews and let’s get to the bottom of this.

  • Denise

    Thank you for your wise words Dr.
    “Then you will know the truth and the truth shall set you free.” Jesus said it in: John 8:32: We all understand this message whether we are religious or not.
    Monsanto and their ilk have lost their way in “the valley of the shadow of death” Greed, power, half-truths, and deception have a strangle hold on them.
    Let us hope they see the light soon. Our agricultural land and all that surrounds it can not take this all-out assault on it, much longer.
    The use of chemicals on the land is completely out of control.

  • John Fefchak

    I am afraid of what is before us because what we sow,we shall also reap______’Dorthy Day’.

    Have we forgotten so soon?
    The relationship between a regulator and the regulated must never become one in which the regulator loses sight of the principle that it regulates only in the public interest and not in the interests of the regulated. ( solemn warning by Justice Horace Krever as he made his address in the Royal Commission of Inquiry of the blood system in Canada.) unquote.

    Unfortunately as it is, our government (s) do not excel or even perform
    well in the responsibility and trust of a regulator.

  • Thomson1

    The UN continues to demonstrate why it is losing credibility and legitimacy on the world stage; it is increasingly pandering to the radical environmental lobby. Disconnected from science with an agenda driven by politics would be an appropriate analysis of this group of “experts”. The classification is politically appropriate but it is an embarrassment to an organization supposedly committed to the scientific method.

    • richard

      …….and the scientific method continues to dispel technological mythology perpetrated by an entire cult of “experts” ie. BSE, BST, CWD, PDE, weed, disease, pest, antibiotic resistance, watershed contamination….and now glyphosate……and the missionaries appear to suffer from a new disease called foot in mouth………

  • debbie3554

    It’s easy to spot the industry talking points being spoon-fed to Solomon; 1) There is NO scientific consensus and 2) The ‘recent German report’ was written by industry connected hacks and shills; it is worthless. Sadly, Guelph U. has become nothing more than an incubator for future workers in the pesticide and GMO industry. The brainwashing is rampant.