Science in Society Archive

“Stunning” Difference of GM from non-GM Corn

A comparison of US Midwest non-GM with GM corn shows shockingly high levels of glyphosate as well as formaldehyde, and severely depleted of mineral nutrients in the GM corn Dr. Mae-Wan Ho

The results of a comparison of GM and non-GM corn from adjacent Midwest fields in the US that first appeared on the Moms Across America March website [1] are reproduced in Table 1.

Table 1   Comparison between GM and non-GM corn grown side by side*

 Parts per million (ppm)
IngredientGM cornNon-GM corn

Calcium146 130

*The GM corn was grown in a field that has been no-till, continuous GM corn (Roundup Ready) for 5-10 years and with a glyphosate herbicide weed control regime for all of the 10 years. The Non-GM corn has not had glyphosate (or Roundup) applied to the field for at least five years. The GM corn test weight was 57.5 lb; and non-GMCorn test weight 61.5 lb.

As Zen Honeycutt, who posted the report commented, glyphosate, shown to be toxic at 1 ppm, is present at 13 ppm in the GM corn. Similarly, formaldehyde at 200 ppm is 200 times the level known to be toxic in animals.

The GM corn was also severely depleted in essential minerals: 14 ppm vs 6 130 ppm calcium; 2 ppm vs 113 ppm of magnesium; 2 ppm vs 14 ppm of manganese 3 ppm vs 44 ppm of phosphate, 3 ppm vs 42 ppm of sulphur, and so on.    

It is not surprising that this analysis has been carried out independently; i.e., not by biotech companies. It was done by farmers themselves. The high level of glyphosate is bad enough. Scientific evidence on glyphosate accumulated over three decades documents miscarriages, birth defects, carcinogenesis, endocrine disruption, DNA damage, neurotoxicity, and toxicity to liver and kidney at levels well below recommended agricultural use (see our recent review [2] Why Glyphosate Should Be Banned, SiS 56). The presence of formaldehyde - a genotoxic and neurotoxic poison at such enormous concentration - is totally unexpected.

Analysis obtained by Midwest farmers

Howard Vlieger, a crop nutrition advisor working with family farmers in 10 states across the US, who has been involved in the study and research of GMOs since 1996, explained in an interview [3] that people want “a side by side comparison” of the corn in the same soil conditions with the only difference being the application of glyphosate based herbicide on the GM Roundup Ready (RR) corn and a conventional herbicide on the non-GM corn. “This has not been done and cannot be done according to the technology agreement signed by a farmer planting GM seed without being at risk of being sued by the patent holder of the GM RR corn,” he said.

In this case, however, ears of corn from two adjacent corn fields in the Midwest, separated only by a fence, were sampled two weeks before harvest. The corn fields were selected by a third party and the samples collected in exactly the same manner. The separately bagged ears of corn were shelled from the cob and the grain samples sent to the lab for glyphosate testing. The non-GM corn field has not been sprayed with glyphosate for at least five years (see Table 1).

The samples were sent to a certified laboratory where it was prepared for testing on gas chromatography-mass spectrometry, an analytical method in which chemical compounds are first separated on a chromatographic column according to their size and charge and other chemical properties, and then ionized and identified based on mass to charge ratios. The RR corn tested contained 13 ppm glyphosate - coincidentally the EPA’s newly set legal limit of glyphosate in corn - while the other non-GM corn sample tested free of any glyphosate. The RR corn sample that tested positive for the glyphosate residue also tested positive for formaldehyde at a level of 200 ppm.

Where does the highly toxic formaldehyde come from?

Plant pathologist and retired Purdue University professor Don Huber, who has been sounding dire warnings on glyphosate poisoning crops, soil, livestock, and people (see [4] USDA Scientist Reveals All - Glyphosate Hazards to Crops, Soils, Animals, and Consumers, SiS 53), commented that formaldehyde can come from degradation of glyphosate [5]. But it can also come from normal plant 1-C metabolism, as for example, de-methylation of serine to glycine plus formaldehyde.

Formaldehyde does not exist in the free-state in a healthy normal plant. It is toxic compound that reacts with proteins, nucleic acids and lipids, and has been classified as a mutagen and suspected carcinogen [6]. Formaldehyde is also neurotoxic, and at ~100 ppm induced amyloid-like misfolding of tau protein, leading to the formation of protein aggregates similar to those found in Alzheimer’s disease; followed by programmed cell death of the neurons [7]. In normal cells and organisms, formaldehyde is detoxified by glutathione-dependent formaldehyde dehydrogenase (GDFDase) to formic acid [8]. GDFDase is dependent on zinc [9], and it is likely that the chelating action of glyphosate [4] may be responsible for inhibiting the enzyme’s activity by depriving it of zinc.

“Of course the scariest part of this is that any RR plant (corn, soybean, canola, cotton, sugar beet or alfalfa) that is sprayed with glyphosate could potentially produce formaldehyde … and then the formaldehyde would unknowingly end up in the feed and food supply.” Vlieger said [3].  The accumulation of formaldehyde was not due to any unusual environmental stress experienced by the GM corn.  “This corn was not raised in an area that was affected by the extreme drought conditions of 2012.”

He also told UK group GMWatch [10] that the glyphosate and formaldehyde could “explain the continuing problems we are witnessing in livestock operations with poor animal health when GMO feed stuffs are in the diet.”

Obviously, the analysis should be repeated on more samples of GM and non-GM corn grown side by side to see if these remarkable differences could be replicated. If so, we can only conclude that previous data submitted by and for the companies that found GM corn “substantially equivalent” to non-GM corn must have been fraudulent, and the perpetrators need to be brought to justice.

Article first published 22/04/13


  1. “Stunning corn comparison: GMO versus non GMO”, Zen Honeycutt, 15 March 2013, Moms  Across America March,
  2. Sirinathsinghji E and Ho MW. Why glyphosate should be banned. Science in Society 56, 21-32, 2012.
  3. “More info on 2012 corn comparison report 12 April 2013, Zen Honeycutt, Mom Across America March 4 July,
  4. Sirinathsinghji E. USDA scientist reveals all, glyphosate hazards to crops, soils, animals and consumers. Science in Society 53, 36-39, 2012.
  5. Huber D. Formaldehyde and glyphosate in corn. Powerpoint presentation, 2012.
  6. IARC Monographs on the Evaluation of Carcinogenic Risk for Humans  62, Wood Dust and Formaldehyde, IARC, Lyon, 1995.
  7. Nie CL, Wang XS, Liu Y, Perrett S and He RQ. Amyloid-like aggregates induced by formaldehyde promote apoptosis of neuronal cells BMC Neurosci 2007, 8, 9.
  8. Achkor H, Diaz M, Fernandez MR, Biosca JA, Pares X and Martinez MC. Enhanced formaldehyde detoxification by overexpression of glutathione-dependent formaldehyde dehydrogenase from Arabidopsis. Plant Physiol 2003, 132, 2248-55.
  9. Barber RD, Ott MA and Donohue TJ. Characterization of a glutathione-dependent formaldehyde dehydrogenase from Rhodobacter sphaeroides. J Bacteriol 1996, 178, 1386-93. 
  10. GMWatch Comment on 2012 corn comparison report. 19 April 2013,

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yara Comment left 22nd April 2013 22:10:18
useful and necessary information. thanks

Debasish Datta Comment left 23rd April 2013 03:03:09
Alas! Not a single positive side in favor of G.M. Yet it is going to be favored in the 3rd. world country.

Christopher Johnson Comment left 25th April 2013 05:05:07
"Obviously, the analysis should be repeated on more samples of GM and non-GM corn grown side by side to see if these remarkable differences could be replicated." Please let your readers here know what plans exist for doing precisely this experiment replication for this growing season. Please name the Universities or independent scientific institutions who will be doing this work - where and when. Also let us know if we can send financial support for this specific research. Thank you.

mae-Wan Comment left 25th April 2013 05:05:13
There have been a couple of abusive comments on this article attacking the anonymity of farmers who have carried out the work, which have been moderated out. But I want to say why these people are chosing the wrong target. The analysis was carried out by a certified laboratory using the "gold-standard" method,gas chromatography-mass spectrometry, and at least one scientist, Prof. Don Huber, and an independent consultant, Howard Vlieger, are prepared to speak openly about it. The farmers concerned are not the ones we should hold to account. They have limited resources, and are always in danger of being intimidated and sued for infringing the technology agreement. Even scientists are afraid to speak out because they would lose their laboratory, their grant, or worse, their job. I know, because I was one such scientist who did speak out. It is governments and the regulatory agencies we should be holding to account. They should now openly support independent scientists to repeat such work on our behalf, instead of accepting what biotech companies choose to submit to them and dictate what information they can make available to the public.

Michael Astera Comment left 27th April 2013 06:06:22
Here is a link to the original online posting of this bogus study: I'll just point out a few egregious errors: *Food products are not measured for CEC, soil and soil components are measured for CEC. *Food products are not measured for % organic matter, soil and soil components are. *Many of the elements listed under base saturation are *not* bases. Exchangeable bases are positively charged ions. *The amounts listed for minerals in the non-GMO corn are absurd. Here are typical mineral amounts for yellow corn flour from the USDA SR25 data base: Minerals (per 100 grams) Calcium, Ca mg 7 (70ppm) Iron, Fe mg 2.38 (23.8ppm) Magnesium, Mg mg 93 (930ppm) Phosphorus, P mg 272 Potassium, K mg 315 Note that corn is low in Calcium, high in P and K. The bogus study lists the Ca content of GMO corn as 14ppm, which is reasonable. The non-GMO corn is listed as having 6130ppm Ca, an amount more than 87 times higher than USDA averages. 6130ppm Ca is what may be found in a typical soil test. SOIL TEST, not crop test. It really would take very little to get accurate figures for minerals: Simply send a sample of GMO and non-GMO corn to the lab for tissue testing. Associating Don Huber's name with this study is misleading; I seriously doubt that he had any connection or was even contacted. Michael A

Mae-Wan Ho Comment left 27th April 2013 07:07:24
Michael, you are right about Ca being greatly out of line with USDA figures for non-GM corn, not so for the other minerals. The really serious findings are the formaldehyde and the glyphosate. You are also right that it is very easy to repeat the analyses, so why don't the USDA and EPA do them? They should do the soils and the grains at the same time for the same crops grown side by side.

Michael Astera Comment left 28th April 2013 00:12:53
Mae-Wan: I would say if the numbers for Ca are wrong, along with the other errors such as CEC and organic matter, which are not food qualities but soil measurements, then the entire list/table is in doubt. I seriously doubt that maize/corn could produce grain with 7 ppm K. I know people who have contacted profitproag looking for answers to these questions and have only gotten the run-around, as in "secret test methods" supposedly done by Midwest labs. I have worked with Midwest labs tests for years and have never heard of these secret tests. My conclusion is that the person who put the table together did not know what they were doing and is now trying to cover their behind. I plan to send samples of organically grown and GMO/roundup corn to the lab for mineral testing soon. Michael A

mae-Wan ho Comment left 28th April 2013 00:12:50
Michael, Please make sure that the lab uses gas chromatography-mass spectrometry testing, and please test also for formaldehyde and glyphosate. I agree we need to get to the bottome of this. I still would not blame the farmers for wanting to remain anonymous.

Michael Astera Comment left 29th April 2013 02:02:39
mae-Wan: I don't think it is farmers wishing to remain anonymous. One of my colleagues reported that he managed to track down and speak with the farmer who grew the corn referenced. The problem appears to be the person behind profitproag who put together this table, from whom no straight answers seem to be forthcoming. Soil mineral balance and the mineral levels in food crops are my business as well as my personal interest because of their connection with plant, animal, and human health. Based on my experience the info published by profitproag makes no sense at all. CEC is not applicable to crops, nor is percent saturation of CEC; those are soil parameters. The soil and plant testing lab I use (which does ICP/MS testing) does not test for formaldehyde etc and I don't think that's necessary in this case. I simply wish to see a side by side comparison of essential mineral nutrients in Roundup-ready GMO corn vs organically grown heirloom corn. Michael Astera

Mae-Wan Comment left 29th April 2013 02:02:00
Michael, Just because cation exchange capacity (CEC) is not usually measured in grain does not necessarily mean that the sample measured was not grain. The technician may have just run through the same routine that is usually applied to soil. In the same way, you can measure pH in soil as well as in grain, and energetic (calorific) content, for that matter. It would be a mistake and wasted opportunity not to measure formaldehyde, as this is the most serious contaminant, and it is very important to find out if this can be confirmed.

Michael Astera Comment left 3rd May 2013 01:01:37
Mae-Wan: In my view, any acceptable research must list the methods used to arrive at the results claimed. In this case we seem to have a "secret" method done by a secret laboratory. For all we know, whoever wrote the original comparison just made up the numbers. The most obvious red flag is the Calcium content. Corn/maize is a low-Ca crop. 100 ppm would be a high level of Calcium for corn. 1500 ppm Ca would be a high level for any crop, even for crops that are known for high levels of Ca such as cabbage and broccoli. More than 6000 ppm Ca in corn grain is not likely. Until I know the methods used for testing and who put the numbers together on the table I do not consider it valid. Michael Astera

Mae-Wan Ho Comment left 3rd May 2013 01:01:14
Michael, I find it hard to believe why anyone would want to make up a bogus table. I agree the Ca figure does seem out of line, and it may have been a mistake.So it would be good to get to the bottom of this by repeating the analysis. Although some scientists feel free to speak out, many still don't; because they genuinely feel intimidated. And while on the subject of people who keep their methods and data secret, why not challenge Monsanto on this, they routinely keep things secret as "confidential business information". As I said, anyone repeating the analysis without doing formaldehyde and glyphosate is simply not addressing the main issue raised, which is safety.

Karl Haro von Mogel Comment left 17th May 2013 17:05:40
"Michael, I find it hard to believe why anyone would want to make up a bogus table." Following the biopolitics of genetically engineered crops, I can think of many reasons. More than likely it was an inappropriate method applied to this situation. Clearly calcium levels that high are wrong, which means that we can't trust the other numbers in this table. I notice that you also omit a considerable number of other numbers which have been pointed out as obviously false. If Monsanto or any other biotech company presented data like this, you would clearly not give it the pass that you are right now.

Kevin Folta Comment left 17th May 2013 17:05:46
C'mon. This is old, debunked. These are data from soil. I blew the lid off of this weeks ago. Formaldehyde comes from time-release fertilizers. Glyphosate may be there in soil. There is no way this is authentic analysis of corn. Look at the numbers. Think about it. There is no way that these numbers even approximate reality or any data ever published. Plus, these aren't published. They showed up on a crackpot anti-GM website. MY OFFER STANDS. I'll challenge anyone to replicate these data. Together, let's run the analysis on replicates and controls. I'll cover the cost if there's this much formaldehyde and glyphosate in the corn, and we'll publish in Nature or Science (you pick). So far, nobody has taken me up on this challenge.

Mae-Wan Comment left 17th May 2013 18:06:54
Thank you all for your inputs. As I said, it will be good to get to the bottom of the data. It has been a very good discussion, and ISIS will be the first to admit the data are bogus, if indeed they prove to be so. But that doesn't mean there is nothing wrong with GMOs. The health and environmental impacts are clear, especially with regard to glyphosate/Roundup and Bt toxins. Where we are still in the dark is regarding the unpredictable and unreliable GM process itself, particularly in the light of new findings in epigenetics and the fluid genome. Do look out for a new report from ISIS, due to be released in weeks.

mae-wan ho Comment left 17th May 2013 20:08:44
Kevin, I have just put you in touch with people who are willing to take up your challenge. Please reply to them. This is very good news for all.

Ken Comment left 18th May 2013 14:02:10
It is a great disservice to us all if incorrect numbers like the calcium are allowed in such a table. It brings legitimate doubt to a danger that is probably true. Beyond the above, it would be a great experiment to have three or fours sets of plantings, GMO with herbicide use, GMO without pesticide use, conventional non-GMO and optionally completely organic plantings.

Kevin Folta Comment left 22nd May 2013 20:08:58
Mae-Wan, unfortunately nobody has contacted me. I have asked publicly at Marching Moms for experimental design input. The only people that want to provide input are scientists. Vlieger, Huber, etc will not dare participate in the challenge-- it exposes those that have rabidly stood by this data as promoting fake data. I appreciate your kind outreach here, but you have not put me in touch with them. They need to contact me. Plus, I need to know what hybrids/genotypes were used. Why was "cation exchange capacity" (a soil test) used on corn and how/why? We need to move fast on this as the season is in full swing. Again, I appreciate your help. When you promote these fake data on your own page here, I think you should also be involved in the new experiment and be an author on the work. We will do a multple-location, many replicate study at mutually agreeable analytical labs, including the one used for these data. Please encourage those that have promoted these data as legitimate to participate in the statistically meaningful study.

Mae-Wan Ho Comment left 22nd May 2013 20:08:04
Kevin, I did put you in touch. I sent a message to to those people copied to you, but you have chosen not to contact them by pressing the reply all button. As I explained. They were reluctant to get involved with you partly because of the pro-GM stance you have adopted in your blogs available on the web. The other reason is that in the mean time they have obtained funding to do the work. I therefore suggested that you should do your experiments independently and to be sure to carry out the experiment with a gas-chromatograpphy-mass spectrometer the same way as described on crops grown side by side. Be sure to measure formaldehyde as well as Calcium.

Jason Godwise Comment left 6th June 2013 16:04:16
If the data is accurate I wonder how the GMO corn can even carry on its basic life chemistry. Also how can any animals chickens, cattle etc feed it survive? I can get you gmo and non gmo corn from my farm in Indiana and we can go to Purdue and test it if you want I would like to get to the truth of this. I think there are dangers of GMO but bad data only causes more confusion??