Glyphosate in breast milk

June 2014

Photo from Creative Commons
Awareness is rising that we are subject to an exponential exposure to herbicide, glyphosate. Besides widespread use in landscaping and conventional agriculture, many GM crops are designed to accumulate this herbicide and they have become ubiquitous in our food chain, adding hugely to the burden.

Experiments on rats suggest 35-40% of ingested glyphosate enters the body.  Because glyphosate is highly soluble in water, it would be expected to disperse throughout body fluids.

Indeed, studies have confirmed that glyphosate is circulating in human blood and is excreted in urine [1,2].  Testing of cows fed GM glyphosate-tolerant GM feed  indicates an even dispersion of glyphosate in the intestine, liver, muscles, spleen, kidneys and urine, and the levels of the herbicide there are correlated with dietary presence.

A senior Monsanto scientist has asserted that “If ingested, glyphosate is excreted rapidly, does not accumulate in body fat or tissues, and does not undergo metabolism in humans.  Rather, it is excreted unchanged in urine”.

Regulators seem happy to accept this view.

However, is glyphosate really doing nothing as it passes through our bodies, as Monsanto says?

Drip-feeding ourselves with the herbicide day-in-day-out could make even a very low level of accumulation or co-lateral physiological effect significant.

Consider also that Monsanto's stated understanding is based on tests of glyphosate.  This isn't necessarily what we're exposed to.  The herbicide is always applied in a formula, such as the many 'Roundup' brands, which have a variety of added chemicals to assist the glyphosate into cells and help it kill more efficiently. 

COMMENT While chemical glyphosate is water-soluble with a limited tendency to move into fatty tissues or through membranes, the added ingredients in Roundup formula are there to overcome this barrier. Glyphosate in Roundup could behave very differently in the body from the way is does, as tested, in isolation.

A recent, very small, independent, exploratory survey in America was prompted by concerns over the current prevalence of glyphosate-sprayed GM crops there.  It suggested that all that the weedkiller just might not be flowing quite so harmlessly out of our bodies through our kidneys as Monsanto would have us believe.

Samples from across the breadth of America yielded some worrying indications:
  • Thirteen out of twenty-one samples of (presumably treated) drinking water had low, but detectable levels of glyphosate.
  • In line with a European study across 18 countries in 2013, thirteen out of thirty-five urine samples had detectable levels of glyphosate. The US levels were ten times higher than those measured in Europe.
  • Breast-milk, a parameter never before studied, had clearly detectable levels of glyphosate in three out of ten samples . Because the concentrations of glyphosate in milk appear to be greater than in urine, there's a possibility that glyphosate is accumulating in the mother's body and being concentrated in her milk.
Is feeding a new-born baby glyphosate safe?

Studies suggesting links between glyphosate and disturbances in calcium metabolism, increased cancer, and hormone disruption suggest it's not [3,4].


It's important to recognise that glyphosate is very difficult to measure in living tissues. Tests for glyphosate have low sensitivity, meaning there has to be quite a lot there before it can be detected at all. The breast-milk sampling was not random but came predominantly from volunteers who took care to avoid pesticide-contaminated food. It was also a very small sample. These would minimise the chances of showing up a problem. The bottom line is that average public exposure to glyphosate could well be considerably greater than that suggested by the pilot study.

There seem to be important data missing from the glyphosate safety assessment. Since this herbicide is known to bind to calcium, it could be expected to accumulate in high-calcium tissues such as bones and milk.

Monsanto's assertions are not wrong. But they should be qualified: “If ingested most glyphosate is excreted rapidly, does not accumulate in body fat or tissues except in bone and milk, and does not undergo metabolism in humans, but can attach to, and interfere with physiologically important metabolites.” It should add that it's statement may not apply to glyphosate in Roundup.

It is urgent that these knowledge-gaps in glyphosate and Roundup safety assessment are filled.

'Moms Across America' and 'Sustainable Pulse' who commissioned the pilot study are calling for:
Adequate long-term independent testing to ensure that glyphosate herbicide formulations as sold and used are not persistent, bio-accumulative or toxic.
US Congress funding for research on glyphosate herbicide formulations including their health effects, how they get into the human body, and current levels of accumulation in people, animals and the environment.

You might suggest that the UK Government adds its voice to this long-overdue request, instead of trying to rush our agriculture down a GM route [5]. Also tell it to ditch the Monsanto-style platitudes about obvious safety issues.


  • World's Number 1 Herbicide Discovered in U.S. Mothers' breast Milk, Sustainable Pulse, 6.04.14
  • Monika KrΓΌger, et al., 2014, Detection of Glyphosate Residues in Animals and Humans, Environmental and Analytical Toxicology 4:2

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