GM safety testing needs today's science

April 2015
It was thought-provoking to read about a Monsanto-sponsored review of glyphosate safety studies. 

The review wasn't published in an open-access journal, meaning that only the abstract is available. However a response by scientists, whose conclusions of harm caused by the herbicide had been dismissed in the review because their end-points (markers of toxicity) had not previously been used revealed the biotech industry's view of 'safety studies'. It seems the industry position is that glyphosate (used on and accumulated by most GM crops) is unquestionably safe because historically-recognised end-points have proven it so, and that any further science is therefore wrong.

There are a number of problems with this logic.

Problem number one - Who dictated the safety tests for GM foods.
Safety-testing of GM foods and their associated chemicals have been largely guided by the biotech industry itself. Likewise any subsequent re-appraisals. 

Testing is expensive and time-consuming, and there is every commercial reason to avoid it, especially the newer, more sophisticated, tests emerging in the scientific literature.

Problem Number two - The limitations of traditional toxicological tests.
Because whole food interacts in complex ways with the physiology, it's difficult to test, so GM food safety tests have been dumbed-down to classical toxicological testing of single chemicals. Such tests are relevant to single chemicals, but are inappropriately narrow and short-term for a whole food: they leave too much out.

Problem number three - Regulators don't use science.
Both regulators and industry insist what they do is based on science. While this is certainly what they should be doing, the reality is biased by practicalities. 

Regulation is a slow process: slow to set the rules and even slower to change them. 

Biotech science is shaped by commercial interests.

To quote one blogger "one of the most important thing about (science). It moves on. It's always moving on ... always changing, and once it's changed, what was science yesterday isn't science any more". The safety science of today shouldn't be confused with the standards set by regulators yesterday.

As technology produces fancier products for sale, safety testing has also become increasingly sophisticated. Glyphosate has become caught in the net of today's science (the kind the biotech industry and regulators don't do - for example see Problems number four, five and six). 

Problem number four - Glyphosate is assumed safe because it doesn't accumulate in the body.

Early biotech industry studies indicated that only 1% of a single dose of glyphosate was retained in the body. While 1% of a one-off dose of a seemingly inert substance is negligible, one percent of chronic exposure, as has been the case since glyphosate-contaminated GM commodity crops came on the market, can mount up.

Problem number five - Other properties of glyphosate with implications for health have been ignored.

Glyphosate is toxic to microbes and binds to metals. While it may not interfere directly with animal physiology, it will alter gut microbial balance with severe effects on health and nutrition, and will alter metal-dependent processes in the physiology, such as essential enzyme reactions.

Problem number six - The biggest one: endocrine disruption.
Glyphosate has been considered exceptionally safe for animals because it's designed to interfere with plant metabolism, it produces no acute toxic effects (except at exceptionally high doses), it's not metabolised in the body and therefore does not induce toxic by-products or interfere with the physiology, and it does not accumulate. Also, there are no established toxicological end-points for which glyphosate produces a classic increased response to increasing dose.

Evidence is accumulating, however, that the biotech industry's best-loved best-money-spinning herbicide, is an endocrine disruptor [1]. (For example, see GLYPHOSATE DISRUPTS OESTROGEN-LINKED GENES coming soon)

Endocrine-related end-points have their own, highly idiosyncratic dose-responses. Very small amounts can have huge effects not seen at higher doses, and the timing and duration of exposure can be critical. Harmful end-points may only be obvious at specific doses over specified time-periods, at key developmental stages or when concurrent with other specific stresses. None of these are identifiable using the classical toxicological tests demanded by regulators under industry guidance.

Studies have suggested, for example, glyphosate's potential for reproductive effects [2] and mammary tumours [3]. Glyphosate's ability to depress antioxidant function in liver cells is very clear, but doesn't increase with dose [4]. There seems to be a potential for reduction in fertility, increase in cancer, and health impairment with won't cause death, but could certainly contribute to it.

Just to complicate the picture, glyphosate is always used in an herbicidal formula (such as Roundup) with added adjuvant chemicals. The formulations are always more toxic than the herbicide alone. In other words, chronic exposure to glyphosate plus adjuvants needs to have a whole new set of end-points defined. This needs today's science.

Now that the legal process has declared glyphosate safe, the only evidence regulators are open to is epidemiological. While the GM lobby try to convince us that Americans have eaten trillions of GM meals without verifiable harm, US Government data shows that Americans are sick and getting sicker. And their increasing sickness correlates uncomfortably with increasing use of glyphosate-based weed-killers [5].


What we seem to need is science (today's not yesterday's) on the safety of what we're actually exposed to (Roundup, not glyphosate) for the time we're exposed to it (from before the cradle to the grave, not a brief interlude during youth), and in real-life circumstances (to include the stressed, the young, the old, and the health-compromised, not just well-fed youth).

Time to suggest a non-industry-led re-think of our whole approach to safety-testing.



[2] ROUNDUP CAUSES BIRTH-DEFECTS - GMFS Archive. October 2010 

[3] GM MAIZE IS NOT SAFE TO EAT - October 2012




  • Brewster, et al., 1991, Metabolism of glyphosate in Sprague-Dawley rats: tissue distribution, identification, and quantitation of glyphosate-derived materials following a single oral dose, Fundamental and Applied Toxicology 17(1)
  • Defarge, et al., 2012, Letter to the editor: Developmental and Reproductive Outcomes of Roundup and Glyphosate in Humans and Animals, Journal of Toxicology and Environmental Health, Part B, 15
  • Amy Lavin Williams, et al., 2012, Developmental and Reproductive Outcomes of Roundup and Glyphosate in Humans and Animals,  Journal of Toxicology and Environmental Health 15:1
  • Derek Bickerton, Unsafe at any dose? 15.02.15, and Claire Robinson comment, GM Watch, 20.02.15

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