Debunking pseudo science “lab testing” health risk claims about glyphosate (Roundup)

On April 7, 2014 a television “documentary” in Australia reported that a study of 10 nursing mother’s milk revealed the presence of glyphosate.  This report referenced claims announced made by a “study” commissioned by anti-GMO activist group Moms Across America with “Sustainable Pulse,” an online “news service” published by anti-GMO campaigner and organic food entrepreneur Henry Rowlands.  Here we provide the science and facts to consider.


Glyphosate is a relatively non-toxic broad-spectrum herbicide sold under the brand name Roundup that has been used for more than 40 years around homes, in landscapes and parks, and in agriculture.  Glyphosate is far less toxic than alternative herbicides, has a broader spectrum of activity, and has fewer adverse effects on herbicide-tolerant transgenic plants than typical herbicides have on most crops.  Since it is not persistent in the environment or groundwater and has low toxicity, glyphosate is generally considered to have less environmental impact than other herbicides. 

An extensive scientific literature indicates that glyphosate is specifically not genotoxic, is not a carcinogen or a teratogen, nor has any specific adverse health effect ever been demonstrated to have been caused by exposure to or low-level consumption of glyphosate.  It has little effect on non-target organisms other than plants; a contributing factor to this is that glyphosate inhibits an enzyme found in plants. This enzyme is not found in humans, other mammals, birds, fish, or insects. 

The use of glyphosate on herbicide tolerant crops has proven problematic to anti-GMO activists since adoption of the technology promotes the switch to a chemical with a lower environmental impact quotient and lower toxicity.  Recently, claims of adverse effects caused by glyphosate have begun to appear.  Although none of the reports has proven credible, it appears that these reports are part of a deliberate campaign to create the False impression that glyphosate is highly toxic and harmful as a basis of calling for bans of glyphosate which in turn would obviate the use of most HT-crop plants.

Points to consider:

1.  The results of these sample analyses were not claimed to be from a proper scientific study; in fact, the report concludes that the results warrant further studies to be done*.  Even in the case of a well-designed and rigorously conducted scientific study, no conclusion is accepted without repetition and independent verification of the study.  The media often runs with the conclusions of single studies, science is more conservative and demands conclusive evidence.

2. A number of factors undermine the strength of this report.   The source of the samples tested and their history of exposure to glyphosate is unknown.  It is not known if the assay method has been validated for human breast milk, since this is not often a tested material, a validation should have been reported.

3.  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.

4.  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.

5.  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. 

6.  It is important to consider the source.  The testing was done for and samples were provided by Moms Across America and Sustainable Pulse; both organizations which oppose any use of GM technology in agriculture and which have a track record of promoting and endorsing flawed and rejected studies that claim harmful effects of GM crops while not citing the overwhelming number of studies that point to the safety of the technology.  Their track record points to a clear bias on this issue.  It is a bias that goes against the scientific literature and the great preponderance of expert opinion.  It also runs counter to nearly 20 years of safe use by millions of farmers on billions of acres of farmed land.

* “The initial testing that has been completed at Microbe Inotech Labs, St. Louis, Missouri, is not meant to be a full scientific study. Instead it was set up to inspire and initiate full peer-reviewed scientific studies on glyphosate, by regulatory bodies and independent scientists worldwide.”

** Detection depends on the sensitivity of the assay system employed.  As more and more sensitive assay techniques are developed, an increasing number of samples can be expected to test positive (see point #5).







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