Study is weighted with conflicts of interest that include having three Monsanto employees as authors
A Monsanto-linked study has found no glyphosate in human breast milk, contradicting other studies that did.
However, questions have been raised about Monsanto’s methodology.
The row over the glyphosate content of breast milk seems set to continue until we see a clear comparative analysis of the different methodologies used to do the tests, as well as of the methods used to select the women subjects.
The Monsanto-linked study is published here:
Monsanto-linked study finds no Monsanto-linked herbicide glyphosate in breast milk
Forbes, 4 April 2016
[links to sources at the URL above]
The herbicide glyphosate does not show up in breast milk, according to findings from a study published in the American Journal of Clinical Nutrition. The study, however, is weighted with conflicts of interest that include having three Monsanto employees as authors. The first two authors also have received grants from Monsanto, and the costs of the chemical analyses for the study were covered by Monsanto. This study is not, however, the only one reporting this outcome.
Glyphosate is a widely used herbicide that Monsanto MON +0.62% manufactures and that represented about 30% of the company’s net sales in 2009, although in 2016, the golden glyphosate goose started to slack off. While glyphosate’s been controversially classified by the International Agency for Research on Cancer as a “probable carcinogen,” that classification is not in agreement with the conclusions of US and EU regulators regarding the compound, which works by inhibiting the production of certain amino acids in plants.
The new study’s first author, Michelle McGuire (**see below for a related update and read here for what I think is supposed to be a rebuttal to this post) initially presented the breast milk results in July 2015 at a conference in Montana. A press release from McGuire’s university billed the findings as ”the first independently verified look” at glyphosate in breast milk and quoted McGuire’s reference to a previous report from a group called “Moms Across America” (MAA) that claimed that glyphosate is present in breast milk:
“The Moms Across America study flat out got it wrong,” said McGuire, who is an executive committee member for the International Society for Research in Human Milk and Lactation and a national spokesperson for the American Society for Nutrition. “Our study provides strong evidence that glyphosate is not in human milk. The MAA findings are unverified, not consistent with published safety data and are based off an assay designed to test for glyphosate in water, not breast milk.”
The American Journal of Clinical Nutrition, which published the McGuire et al. study, is one of the journals of the American Society for Nutrition, for which McGuire is described in the release as being a “national spokesperson.” McGuire says that she has the role as a recognized expert in nutrition whom the association trusts to communicate science-based facts to the public because they don’t have “in house” experts.
The reason for the difference in the findings, according to the McGuire et al. paper, has to do with using the right “matrix” for testing for glyphosate. The MAA testing results, which weren’t published in a peer-reviewed journal, didn’t use a test validated on a breast milk matrix and instead used one that relies on a water base. MAA reported having found glyphosate in three of ten breast milk samples. The group also reported finding glyphosate in urine.
A critique of the MAA findings suggested that the testing used was not appropriate, that MAA is an “anti-GMO activist group,” and it “is important to consider the source” when evaluating its claims. The laboratory that assessed the MAA samples used a detection method based on antibody binding to glyphosate, with the three positive results near the detection limit of the test used. That means some wiggle room around whether or not the results mean anything; as some who evaluated the MAA results noted, even the amounts reported in those three samples don’t meet the bar for concern.
In this new paper by McGuire et al., the authors stake a claim on having used the correct matrix for their samples. Rather than using antibody binding to indicate the presence of glyphosate, the two labs analyzing the samples in McGuire et al. instead used a method that separates and identifies the contents of a sample by mass. They used this highly sensitive technique to look for both glyphosate and its metabolite, known as AMPA, in urine and breast milk samples from 41 lactating women.
While McGuire’s team found glyphosate in “nearly all” (39/41) of the urine samples, which makes sense because urine would be one obvious way for the body to get rid of it (poop is another), they found none in breast milk.
They also compared glyphosate content in urine from breastfeeding mothers on a self-reported organic diet versus mothers who reported consuming a conventional diet. Numerically, urine levels were higher in women on a conventional diet, but the results were not significant.
In addition to having the samples analyzed at Monsanto’s lab, the team also had the samples analyzed at Covance labs. The results between the two labs were reported to be the same: no glyphosate in the breast milk samples.
If we take the advice above to “consider the source,” the optics on this study could look suspect, involving the journal, the society associated with it, a ”spokesperson” and Monsanto. A read of the conflict-of-interest statement on the McGuire et al. paper will undoubtedly set red flags a-waving for some people:
“In 2014, MKM (Michelle McGuire) and MAM each received a $10,000 unrestricted research gift from Monsanto; these funds were used to support their research related to human and bovine lactation. These funds were neither needed for nor used to cover the costs associated with the project described in this article, because the milk was already being collected for another project funded by the National Science Foundation (1344288) related to international variation in human milk composition and because additional expenditures associated with the collection of urine samples were negligible. All costs associated with the chemical analysis of milk and urine samples at both Monsanto and Covance were paid for directly by Monsanto. MKM and MAM were once reimbursed for costs associated with economy travel and basic accommodations incurred for a trip they made to St. Louis, Missouri, to discuss study design and assay development with coauthors DAG, PKJ, and JLV at Monsanto. DAG, PKJ, and JLV are employees of Monsanto, which manufactures glyphosate. None of the other authors reported a conflict of interest related to the study.”
Luckily for science and those interested in a compelling, unconflicted evidence base (does that exist?), the Germans have something to add. Reflecting the US pattern, one German group analyzed 16 breast milk samples using the antibody-based test and reported finding glyphosate in all 16 samples (sorry – it’s in German).
But another German group analyzed 114 samples of breast milk for glyphosate content, using a similar approach as that used in the labs in McGuire et al. The method the latter researchers applied has a very low detection limit, and they reported finding no glyphosate in any of the 114 samples. In their paper, they declared having no conflicts of interest.
In an update, the researchers who performed the initial testing in the 16 samples said:
“The Federal Institute for Risk Assessment (BfR) responded to our sampling and carried out their own tests, in which no Glyphosatrückstände (glyphosate residue) was found in breast milk. There is therefore no reason to refrain from breastfeeding. Breastfeeding remains the best food for babies. All food alternatives are expected to be hardly be less polluted anyway.”
A pair of researchers from Abbott Laboratories also assessed glyphosate in a number of different sample types, including human breast milk and cow’s milk, and found none. McGuire’s team has another paper on the method itself (same COIs) that reports finding no glyphosate in cow’s milk.
In general, the consensus is that glyphosate wasn’t expected to bioaccumulate and end up in breast milk in the first place. This set of studies, some with their share of conflicts of interest and some apparently without, support that expectation with results from highly sensitive tests. Whatever else glyphosate does, it doesn’t seem to end up in milk, cow or human.
** Michelle McGuire posted a comment on this piece, as follows:
“Emily, I’m so surprised that you didn’t take the time and make the effort to reach out to me prior to writing this story. Seems like that would have been a critical step you should have taken to make sure you had your facts straight. So disappointing.”
In response, I emailed McGuire so that she could let me know areas where the facts are incorrect. In her replies, she did not highlight any facts to correct, but she believes that the stated information about the conflicts of interest (COIs) in the article suggests in some way that the COIs weren’t adequately managed. I don’t imply that; they seem transparent to me, although I suspect that in some quarters, that won’t be the impression. She also states that there are no COIs related to the American Society of Nutrition (ASN) and believes that being a spokesperson for the organization that also publishes the journal where the paper appeared is not a COI; there is “no overlap” between the journals and ASN, says McGuire. McGuire also does not like the use of “slumber party,” which she finds “particularly offensive”; I could see where that could be construed as sexist and have changed the language.