Glyphosate in wine and cereal? Why dubious detection methods undermine GMO scare claims

Moms Across America (MAAM) says a study it commissioned found the herbicide glyphosate in parts-per-billion (ppb) amounts in California vineyards. MAAM says this is clear evidence of “widespread contamination” by the herbicide, which is used by almost all conventional farmers but is also often paired with some genetically modified crops:

18.74 ppb from a 2013 Cabernet Sauvignon from a conventional, chemically farmed vineyard. The lowest level was from a biodynamic and organic vineyard, 2013 Syrah, which has never been sprayed according to the owner, with a level of .659 ppb. An organic wine from 2012 mixed red wine grapes had 0.913 ppb of glyphosate.

MAAM was not the only group to find tiny residues of the world’s most-used pesticide, an herbicide that has raised the ire of anti-GMO groups for its use with“Roundup-ready” corn, cotton and soybeans.

bread-cereal-bars-water-contaminated-with-toxic-glyphosateIn May, the Alliance for Natural Health (ANH) commissioned a study that found ppb levels in Quaker Oats products, ranging from 86 ppb for Original Silk Soy Creamer Non-GMO, to 1,327 ppb (which translates to 1.33 parts-per-million or ppm) Quaker Instant Oatmeal, Strawberries and Cream. “We expected that trace amounts would show up in foods containing large amounts of corn and soy,” said Gretchen DuBeau, executive and legal director of ANH-USA. “However, we were unprepared for just how invasive this poison has been to our entire food chain.”

So has glyphosate ‘infiltrated our food supply’ as anti-GMO and anti-chemical campaigners claim? Or are there problems with MAAM’s and ANH’s science?

What you want to see may not be what you get

It is important to realize that what’s been found in these rather unsophisticated studies are very, very small amounts of the chemical–far below the US Environmental Protection Agency tolerance levels for residues of glyphosate on crops. The EPA ‘danger’ levels vary among plant types, but range from 30 to 100 ppm for cereal grains, to put the Quaker Oats study into perspective. In addition, those cut offs have a 10- to 100-fold buffer. For reference, West Virginia University’s National Environmental Services Center states that one ppb is equivalent to a pinch of salt on 10 tons of potato chips. None of these anti-GMO commissioned studies suggest levels anywhere near those levels.

There’s also another problem with these residue studies: because of the lack of rigor of these tests, the glyphosate they “found” might not even be there. A close look at the methods of both studies casts a cloud on the groups’ claims. The tests by ANH and MAM were conducted by a company, Microbe Inotech, based in St. Louis, using a method known commonly by its initials ELISA. Short for “enzyme-linked immunosorbent assay,” this test takes an antigen (which in this case is whatever molecule you’re trying to study) and binds it to a specific antibody, which itself has been bound to an enzyme. The antibody is often labeled radioactively for easy detection. Then, the enzyme-antibody-antigen complex is linked to a substrate.

Related article:  Glyphosate and cancer—revisited

While ELISA has been a valuable test for determining the existence of a wide range of chemicals (standard cholesterol and clinical blood tests rely heavily on ELISA), it does not work so well in minuscule quantities like when measuring glyphosate at ppb levels.

When measuring in his range, the most appropriate technique is gas chromatography/ mass e8950200b921547630ad78b4993aa560spectrometry, (GC/MS), in which measures chemicals by their mass and charge. This is a longer (and admittedly more expensive) procedure, but it is extremely accurate.

Referring to the MAAM study on wine, Peter Davies, emeritus professor of plant biology at Cornell University, remarked to me that:

Unless I see the actual analytical data, I take such unpublished results with a grain of salt, especially when the only data presented is levels in a non-peer reviewed report…

ELISA is notoriously susceptible to interference by the presence of other compounds, both in the positive and negative direction, and while fine for a first approximation, it is not acceptable for a definitive measurement. No top ranked journal in the field accepts ELISA as definitive proof for small molecules unless accompanied by further proof. The gold standard is multiple ion mass spectrometry after HPLC and or GC, or as MS-MS.

There is one yet-to-be-released test on glyphosate using a more sensitive technology. Currently touted by the anti-GMO US Right To Know Organization, the test was conducted by the Detox Project, a group with strong anti-GMO connections. In May, US Right to Know announced:

More fuel was added to the fire this week when a coalition of scientists and activists working through what they call “The Detox Project” announced that testing at a University of California San Francisco laboratory revealed glyphosate in the urine of 93 percent of a sample group of 131 people. The group said it used a method known as liquid chromatography-mass spectrometry or LC/MS/MS, to analyze urine and water samples. (The group said it found no glyphosate residues in tap water.) Further data from this public bio-monitoring study will be released later in 2016, according to the group overseeing the testing.

So far, the only data released shows glyphosate levels between 3.1 and 3.6 ppb. Even if true, the EPA tolerance on anything is 30-100 ppm, so these levels are still far, far below what years of scientific research has established as safe.

When the data in the USRTK are released it would be valuable for people to not only look at the actual concentrations—but to review the methodology, too.

Andrew Porterfield is a writer, editor and communications consultant for academic institutions, companies and nonprofits in the life sciences. He is based in Camarillo, California. Follow @AMPorterfield on Twitter.

8 thoughts on “Glyphosate in wine and cereal? Why dubious detection methods undermine GMO scare claims”

  1. A review of the documented procedures and raw data from University of California San Francisco laboratory that conducted the LC/MS/MS based analyses by independent 3rd parties, highly knowledgeable in trace organic analyses and pesticide residue chemistry, is certainly in order. In my experience, some University labs are amazingly sloppy, lack documented procedures and produce dubious results.

  2. ELISA is entirely the wrong test for this and why are they not looking for AMPA the metabolite? The first time I ever heard of glyphosate was in a vineyard in Monterey county in 1977. It was the exciting new way to control weeds in the vine row without using a “French Hoe” that did mechanical tillage and which caused erosion and frequent injuries to the vines. It was a huge success for sustainable grape growing decades before RR crops. Woody crops are naturally “Roundup Ready” in that it is only absorbed through green tissue, not trunks.

    • Some studies have looked for AMPA and concluded that this adds up to the measured glyphosate level. At least in Germany they may have given up to measure AMPA for a good reason: organic farmers and their lobby try to get potassium phosphonate approved again as a “natural fungizide and plant enforcement agent” (German organic wine farmers had up to 100% losses this year due to fungal infections). Potassium phosphonate is also metabolised to AMPA. So it is probably better not to measure AMPA.

  3. Two comments on this very nice review. First, tolerance levels in crops are not danger levels- they reflect actual residues expected w proper use. All uses are considered jointly to assure total consumption is appropriate. Second- commodity tolerances can’t be directly compared to urine levels- but urine data confirms exposures far below any level of health concern.

  4. The meaning of a difference by orders of magnitude, here the difference between parts per million and parts per billion, is likely to be overlooked, not understood by the normal reader.

    The German Green party recently ran a scare campaign with claims of Glyphosate in mothers milk – which was consequently found to be based on false lab/testing data.

    • That Story was hilarious. The milk samples came from Party members and they were analyzed by the Biocheck co. recently founded by the famous anti-GMO expert Dr. Monika Krüger. After they claimed glyphosate in breastmilk at 0.2 -0.4 ng/ml. the BFR (Bundesinstitut für Risikobewerung) got involved. Using LC-MS/MS and GC-MS/MS they conclude that there’s no glyophosate in breastmilk and that concentrations below 1 ng/ml cannot be detected anyway. The reactions of the German Greens: “if it hadn’t been for us there still wouldn’t be a sensitive method to check for glyphosate”. And what did the Biocheck co. respond to this evident criticism of their work? Well, the Managing director of Biocheck says that the sensitivity of their methods were confirmed by an Independent lab, lead by Dr. Monika Krüger, who in turn claims that not hers but another lab did the controls, and the director of that last lab says he knows from nothing (in German here:

    • The German “study” on breast milk was actually triggered by the previous one done by MAAM. It was an easy, cheap and very successful campaign for the German Green Party that was widely covered by the media. I had discussed that with a journalst who said that the data published by the Green Party on Facebook (!) were so clear that no additional journalistic research was required. Scientific data by the BfR (German government institution for risk assessment) and by Michelle McGuire (Illinois Univ.) were brushed away because they were “obviously biased”.

Leave a Comment

News on human & agricultural genetics and biotechnology delivered to your inbox.
Optional. Mail on special occasions.

Send this to a friend