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Points To Consider: Unfounded Claims of Glyphosate Accumulation in Breast Milk


Original Sources:  Press Release: “Glyphosate Testing Full Report: Findings in American Mothers’ Breast Milk, Urine and Water,” Mom’s Across America; Article: “World’s Number 1 Herbicide Discovered in U.S. Mothers’ Breast Milk” by Zen Honeycutt and Henry Rowlands, Sustainable Pulse

Primary Claims:

  • “In the first ever testing on glyphosate herbicide in the breast milk of American women… found ‘high’ levels in 3 out of the 10 samples tested. The shocking results point to glyphosate levels building up in women’s bodies over a period of time, which has until now been refuted by both global regulatory authorities and the biotech industry.”
  • “The levels found in the breast milk testing of 76 ug/l to 166 ug/l are 760 to 1600 times higher than the European Drinking Water Directive allows for individual pesticides (Glyphosate is both a pesticide and herbicide). They are however less than the 700 ug/l maximum contaminant level (MCL) for glyphosate in the U.S., which was decided upon by the U.S. Environmental Protection Agency (EPA) based on the now seemingly false premise that glyphosate was not bio-accumulative.”

Salient Facts and Context:  

  • This “study” is not a study, but a press release from two professional opponents of agricultural biotechnology.
  • The “paper” presents a handful of dubious data points accompanied by numerous claims that are unsupported by credible data and contradicted by the scientific literature and experience.
  • There was no scientific peer review.
  • The description of the methods used is minimal, sufficient only to dismiss the claims as being unreliable, at best.
  • The sampling technique, study design, sample size, use of appropriate controls, and other experimental design parameters all fall short of what would be expected from a High School science fair project.
  • According to the press release, the “study” was “not meant to be a full scientific study. Instead it was set up to inspire and initiate full peer-reviewed scientific studies on glyphosate.”
  • These activist claims avoid any mention of the vast number of peer-reviewed scientific studies that have already been conducted on glyphosate, documented by, among others, the European Union and the World Health Organization and corroborated by extensive real world experience  by the stewards of farmlands and landscapes around the world.

Published Analysis/Rebuttal:

This press release has been specifically discredited by multiple expert sources:


This propaganda salvo is a vehicle for claims, insinuations and innuendo that are abundantly contradicted by a mass of scientific literature and a vast body of real world experience by the stewards of farmlands and landscapes around the world.  Rather than providing the extensive corrections a full rebuttal would require, we will focus on a few salient issues that provide an overall indication of the reliability of the claims made.

Safety:  The safety of glyphosate, when used as directed, is not in question. It is inarguably safer than many of the older generation of weed control measures it has replaced. Recent reviews summarized the literature on glyphosate and human safety:

Epidemiologic studies of glyphosate and non-cancer health outcomes: a review (2011).

Epidemiologic studies of glyphosate and cancer (2012) and

Developmental and reproductive outcomes in humans and animals after glyphosate exposure: a critical analysis.

All of these confirm the longstanding findings of glyphosate’s safety to humans.

Claims of Bioaccumulation: Even if the findings claimed are repeatable, they confirm what has long been known: that glyphosate is rapidly eliminated from the body. This is the opposite of bioaccumulation, and nothing presented suggests any reason to reconsider the well founded understanding that glyphosate does not bioaccumulate. Three (allegedly) positive data points from a total of ten do not make a credible data set.

It is conspicuous that the map provided in the original press release shows an inverse correlation between the claimed detections of glyphosate in breast milk and the areas of the country where glyphosate is used more heavily in agriculture. This observation is not consistent with the claims that increased use is responsible for the reported results.

Parties interested in further considerations cannot do better than to review the analysis by Dr. Bruce Chassy . An excerpt is below.

“The results reported are not consistent with US data on glyphosate in human subjects, and at face value raise a number of questions.  Glyphosate is rapidly excreted primarily in the urine and there is no data to indicate that it accumulates in fluids such as breast milk or serum or in tissues.  Glyphosate is often not detected in urine**, and when it is observed urine values are usually about 10-fold higher than serum values since it is efficiently excreted.  Since glyphosate is not fat soluble, serum and breast milk values would be expected to be very similar which is not the case with the data reported for the 10 breast milk samples that were analyzed.  Why breast milk samples would have an uncharacteristically and unexpectedly high content of glyphosate relative to serum and urine values is open to question but sample contamination and/or unreliability of assay are plausible explanations.

The finding that 3 or the 10 samples had “high” levels of glyphosate is misleading in two ways.  Firstly, high in this case means measurable above the lower limit of detection rather than high meaning a cause for alarm.  The highest of these 3 samples, if real, contained glyphosate at levels that represent a worst-case infant exposure (33 ug/kg/day) more than 50-fold below the ADI (Acceptable Daily Intake) set by US EPA regulatory toxicologists (1750 ug/kg).  The ADI is set to provide a wide margin of safety of exposure.

The US Centers for Disease Control and Prevention note, “Just because we can detect levels of an environmental chemical in a person’s blood or urine does not necessarily mean that the chemical will cause effects or disease. Advances in analytical chemistry enable us to measure low levels of environmental chemicals in people, but separate studies of varying levels of exposure determine whether specific levels cause health effects.”  Food naturally contains a wide-array of potentially toxic chemicals such as cyanide, strychnine, carototoxin, and arsenic but they are usually present at levels that do no harm.  Any chemical, whether natural or human-made can hurt us if we consume too much of it.  Even table salt or iron can kill if too much is consumed.  The mere presence of glyphosate in serum, urine or mother’s milk is not a cause for alarm unless the levels are above those known to do harm.  Over 4 decades of research studies and real-world use, including studies on large numbers of people who have been exposed to glyphosate, have allowed regulators to understand and set safe levels of exposure.  Research has also established that the low levels of glyphosate sometimes found in bodily fluids pose no threat to health.  WHO, EFSA, EPA and other regulatory agencies around the globe have concluded that trace levels of glyphosate in food should be of no more health concern than the presence of myriad potentially toxic chemicals that occur naturally in food.”


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