Roundup impairs adrenal function

October 2015

Several studies have identified glyphosate herbicide, used as 'Roundup' formula on most GM crops, as an endocrine disruptor. Experiments have indicated, for example, health-damaging changes of testosterone (male sex hormone) in rats and of oestrogen (female sex hormone) in human cells. A new study has examined the effects of Roundup on adrenal gland function (see note below). 

Rats were administered Roundup for 14 days at a dose found to produce no overt signs of toxicity, weight-change, nor altered food consumption. At this level of exposure, routine tests would declare Roundup 'safe'.

It was found that the herbicide decreased the levels of adrenal (corticosteroid) hormones in a dose-dependent manner. The effect was one of 'slowing down': gene expression associated with adrenal hormone production was down-regulated in Roundup-treated rats, the processing of cholesterol seemed to be depressed, and the adrenal glands were heavier and had more fat-droplets in them.

No signs of Roundup-induced toxicity in any tissues were observed, but there was evidence that the reduced adrenal hormone levels were actually a knock-on effect from the herbicide's impact on hypothalamus-pituitary activity.

Interestingly, in the course of establishing the dose of Roundup at which there were no overt toxic signs, it was found that at 50 mg/kg body weight there was significant weight loss. This was a much lower dosage than had produced such an effect in previous studies. Although the rat strain used was a common experimental laboratory strain, it wasn't the 'Sprague-Dawley' strain used by Monsanto and others in glyphosate safety tests. Male Sprague-Dawley rats given Roundup at over 500 times that used in the adrenal study for 91 days (i.e. six times longer exposure) showed no effect on body weight (although pregnant Sprague-Dawley females exposed for only 10 days did). This huge discrepancy highlights the ease with which endocrine disruption can be missed by, for example, limiting experiments to insensitive animal strains, or to insensitive life-stages, or to males or females only, or by using too short a duration of treatment.

GM Watch has pointed out the implications of this study for the 'acceptable daily intake' (ADI) for glyphosate which has been set by EU regulators (and which has been set by US regulators at six times that of the EU).

The ADI is normally defined as one-hundredth of the lowest dose found to have no adverse effects in animal tests. If the 'no adverse effects' level has been over-estimated, the safety margin is eroded and the ADI may be harmful. In adult rats this reference so-called 'safe' dose for glyphosate is only three times the level now found to disrupt adrenal function. Worse, glyphosate's no adverse effect dose for rat offspring was a third of the adult dose, making it equivalent to the level proved to affect the adrenals.

Moreover, the current study established a dose at which there was no overt toxicity, but found clear signs of endocrine disruption. Since lower doses of glyphosate haven't been tested, the 'no adverse effect' dose to which the safety factor of 100 could be applied to establish the ADI is simply unknown, and may not exist.

Another problematic aspect to layer on top of all this is that the ADI was set for chemical 'glyphosate', while what we are always exposed to is glyphosate formulated into 'Roundup'. In Roundup, glyphosate is combined with other (often secret) chemicals designed to increase its toxicity: no safety testing has been required and no ADI has ever been established for such toxin-boosting, non-glyphosate components of Roundup.


Chronically sluggish adrenal glands accumulating fat are not good news. Nor is any direct interference with the pituitary/hypothalamus endocrine control hub.

Glyphosate-based herbicides are used on most staple GM crops, on many non-GM crops (to speed up harvesting), in gardens, and in public areas. They are being used in increasing quantities due to galloping glyphosate-resistance in weeds, and due to increases in allowable residues of glyphosate in food and crops in step with burgeoning usage and not in step with human safety considerations. 

Establishing whether there is any acceptable 'acceptable' daily intake for Roundup is urgent. Put this to your MEP.

* Note: The adrenal glands

The adrenal glands are located adjacent to the kidneys. Their function is the production of multiple steroid (cholesterol-derived) hormones. 

The major class of hormones produced by the adrenal gland is the corticosteroids. Corticosteroids regulate energy production, stress responses, blood-pressure, cardiovascular function, the immune system and inflammatory reactions.

Adrenal responses are integrated into the whole-body endocrine hormone system, in particular the hypothalamus-pituitary control centre connected to the brain. 

Symptoms of adrenal/corticosteroid insufficiency include fatigue, muscle weakness, anorexia and weight loss, sweating, anxiety, tremors, nausea and heart palpitations.

Chronic adrenal insufficiency can be fatal.

  • Aparamita Pandey and Medhamurthy Rudraiah, 2015, Analysis of endocrine disruption effect of Roundup in adrenal gland of male rats, Toxicology Reports 2
  • Roundup is an endocrine disruptor - new study, GM Watch 18.08.15
  • Robert M. Sargis, An Overview of the Adrenal Glands,
  • Adrenal Disorders,

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