Rigging the science (and the regulations)

March 2019

Scientists recognise three pillars of data considered key to the judgement of whether a substance might cause, or contribute to, cancer, namely laboratory animal experiments, gene disruption assays, and epidemiological studies. These pillars respectively show that the test substance can be linked to cancer in mammalian models, that there's a demonstrable mechanism for cancerous cell formation, and that there are signs of real-life cancers in an exposed population.

In 2015, the International Assessment for Research on Cancer (IARC) examined glyphosate-based herbicides which are used on most GM crops [1]. It found "sufficient" evidence in animal studies, "strong" evidence of cellular and genetic damage of a kind known to induce cancer, and a suggestion of an association with cancer in a large US farm study (the Agricultural Health Study). The latter is on-going, and the authors indicated that the suggested link "should be followed up as more cases occur" over time [2].

Predictably, Big Biotech rushed its damage-limitation machine into action, persuading willing regulators to accept its own, industry-style, science in lieu of the peer-reviewed science assessed by the IARC. The US Environmental Protection Agency (EPA) accordingly pronounced glyphosate "not likely" to cause cancer.

However, two studies have just been published which cast doubt on the integrity of the US regulator's conclusion.

The first study compared the very different data sets used by the EPA and IARC to reach their diametrically opposed conclusions.

Of the 95 unpublished industry studies on genotoxicity relied on by the EPA*, only 1% was positive for cancer. In the 211 published studies used by the IARC, 74% were positive.

A weight-of-evidence approach couldn't help but take the conclusions of the two bodies in opposite directions.

If this difference in outcome seems extreme, there's a clue as to how it happened in the nature of the studies supplied by industry and ignored due to questions of their validity by the IARC. Over one-half of all the registrant data sets used by the EPA were based on a standard bacterial mutation assay. The test provides a useful and inexpensive, but not definitive, indication of mutagenic potential of a substance. The EPA requires just one such test be carried out for submissions, yet 51 were carried out (and accepted) for glyphosate. That's 50 redundant tests whose negative outcome had already been ascertained (some would say 'pre-ordained').

COMMENT This casts an interesting new light on biotech industry advocates oft-repeated claim that "800 studies show Roundup is safe". At the above rate of duplication of assays with a known 'safe' outcome, the 800 would boil down to 16. 

A second point made in the EPA vs. IARC comparison was that the first body considered exposure to glyphosate alone, despite this never being a reality, while the IARC considered exposure to the much more toxic, real-life glyphosate-based formulations such as Roundup.

COMMENT This scientifically unjustifiable 'safety' testing of glyphosate in isolation suggests that the claimed "800 studies" showing Roundup is safe may boil down to zero.

Oddly enough, when it came to levels, of exposure, the EPA changed tack and got real, refusing to consider anything but "typical" dietary contamination as a result of legal uses of glyphosate.

Aware of the inevitability of elevated, occupational exposure to herbicides caused, for example, by spills, leaky equipment or wind, the IARC assessment encompassed these besides dietary levels.

This last point is reinforced by the second study just published. This is a meta-analysis of six epidemiological trials, one of which was the most recent, 2018, update of the Agricultural Health Study (not available for earlier assessments which had only the 2005 version) It also avoided diluting any cancer trends by focusing on people with a high exposure to glyphosate. The authors concluded that overall, there's a 41% increased risk of non-Hodgkin lymphoma in individuals exposed to glyphosate-based herbicides.

Three of the authors of this study were part of the EPA's scientific advisory panel on glyphosate, and had previously stated publicly that the EPA failed to follow proper scientific practices in its glyphosate assessment. One of the authors said of the EPA and its assessment:
"It was wrong. It was pretty obvious they didn't follow their own rules. Is there evidence that (glyphosate) is carcinogenic? The answer is yes."


It seems the "suggested association" of cancer in the 2005 report of the Agricultural Farm Study did indeed crystallise over time.

Avoiding peer review, repeating a negative test ad infinitum (when much more sophisticated ones are available), choosing the least toxic version of a substance and the subjects with the least possible exposure can only be RIGGING THE SCIENCE.

Europe could ban glyphosate at the end of 2022 when the current license expires. Make sure there's the political will in Westminster to follow suit.


[2] NOISE ABOUT CANCER - October 2015

*Unpublished regulatory studies accounted for 63% of the EPA's evaluation but weren't used at all by the IARC.


  • Charles Benbrook, 2019, How did the US EPA and IARC reach diametrically opposed conclusions on the genotoxicity of glyphosate-based herbicides? Environmental Science Europe, 31:2
  • Luoping Zhang, et al., February 2019, Exposure to Glyphosate-Based Herbicides and Risk for Non-Hodgkin Lymphoma: A Meta-Analysis and Supporting Evidence, Science Direct
  • How did the US EPA and IARC reach opposite conclusions about glyphosate's genotoxicity? GM Watch, 14.01.19
  • Carey Gillam, Weedkiller 'raises risk of non-Hodgkin lymphoma by 41%' , Guardian, 14.02.19
  • Michael Butler, New meta-study reinforces evidence that glyphosate herbicide is probable human carcinogen, Michael Butler blogspot, 14.02.19
  • Simon Marks, Glyphosate is here to stay in EU - at least for now,, 14.08.18
  • UW study Exposure to chemical in Roundup increases risk for cancer, University of Washington  Release,, 13.02.19
  • Exposure to glyphosate-based herbicides increases risk of non-Hodgkin lymphoma - new analysis, GM Watch, 12.02.19
  • Pam Dempsey, Q&A: Here's what one expert in the $290 million case against Monsanto had to say about the trial, Investigate Midwest, 14.08.18.
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