From GMO Pundit.
Many women, no Cry by Marcel Kuntz 29 April 2011
A recent publication by Aziz Aris and Samuel Leblanc in the journal Reproductive Toxicology (Maternal and fetal exposure to pesticides associated to Genetically Modified Foods in Eastern Townships of Quebec, Canada) claims to have detected traces of:
herbicides (used on herbicide tolerant ‘genetically modified’ plant varieties) or their major metabolite,
and the insecticidal protein Cry1Ab (produced by certain varieties called Bt-resistant insect pests)
in the blood of Canadian women, pregnant or not pregnant, and in umbilical cords.
Th[e Kuntz] site will publish any credible information about the validity of these claims and this article will be updated periodically.
A publication lacking credibility
Only claims of Aris and Leblanc on Cry1Ab are discussed here for the time being.
The Cry1Ab protein is produced by some Bt cotton and corn (e.g. MON810).
Aris and Leblanc claim they detected this protein in 93% of pregnant women and 69% of non-pregnant women tested and believe that this is linked to the consumption of foods derived from Bt varieties, which in Canada must mean corn rather than cottonseed oil.
Surprisingly, the authors do not consider that the origin of Cry1Ab could be food from organic farming (which sprays Cry1Ab, or bacteria producing it, on fruit or vegetable crops) or from its use in gardening (CryA1b is part of available “natural insecticide” formulations).
If we examine the possibility of a Bt corn food origin for Cry1Ab, since these proteins do not bioaccumulate, it is necessary to consider recent consumption.
First question: do 93% of pregnant women in Canada actually consume corn almost daily?
Second question: are the values in blood reported by Aris and Leblanc consistent with the levels present in Bt corn kernels?
The answer is no. Here is why:
The authors reported average values of 0.19 nanograms per milliliter (ng / ml) of blood from pregnant women. Knowing that, in corn MON810 for example, levels of Cry1Ab in the grain are between 190 and 390 ng / g fresh weight, assuming that 1% will pass into the blood (which is on the high side taking into account losses during corn storage, cooking, gastric digestion and the intestinal barrier), this would require a woman of 60 kg to consume 120 g of corn (for the mean blood value of 0,19 ng / ml, assuming a plasma volume of 2.5 liters) and about 1.5 kg (for the maximum reported blood values of 2.28 ng / ml), which seems unrealistic … And even more if one takes into account all extracellular fluids (10 liters, which would imply an average consumption of 490 g of corn and 5.8 kg in order to reach the maximum value in blood).
Third question (which follows logically the above-mentioned findings): is the Cry1Ab detection method used by Aris and Leblanc reliable?
Note first that the test used, marketed by Agdia is claimed to detect the protein Cry1Ab from 1 ng / ml (read the introduction to this article).
While Aris and Leblanc claim to have detected average concentrations lower than the detection limit, e.g. 0.04 ng / ml in umbilical cords!
One can cite the publication by Lutz et al. (J. Agric. Food Chem. 2005, 53 (5) :1453-6) showing that the ELISA test used by Aris and Leblanc is not sufficient to guarantee the identity of positive signals (« to avoid misinterpretation, samples tested positive for Cry1Ab protein by ELISA should be reassessed by another technique »).
Note that Aris and Leblanc did not discuss this issue, nor the results of Chowdhury et al. (J. Animal Sci., 2003, 81:2546-2551) which indicate that these ELISAs do not work for blood (from pigs)…
Moreover, they do not cite the publication by Paul et al. (Analytica Chimica Acta 2008, 607: 106-113) that discusses the validity of the tests available on the market…(Provisional) answers to the questions that arise: in the absence of the validation of the detection of Cry1Ab, it is likely that the authors, incorrectly, conclude that any signal was indicative of the presence of the Cry1Ab protein, whereas they most likely correspond to false positives.
A possible validation, which surprisingly is lacking in the work of Aris and Leblanc, is the electrophoretic separation of plasma proteins and immunodetection of the protein Cry1Ab (‘Western blot‘, a common laboratory technique).
It therefore appears that this publication, in its present state, is of unsufficient quality to be convincing. It has not undergone a proper review process according to the standards of a scientific journal, which would have required the validation of the results and their discussion in relation to available literature.
FSANZ response to study linking Cry1Ab protein in blood to GM foods Accessed 30 May 2011
There has been some media speculation about a recent paper published by Aziz Aris and Samuel Leblanc titled ‘ Maternal and fetal exposure to pesticides associated to genetically modified foods in Eastern Townships of Quebec, Canada’ [Reproductive Toxicology, in press, 2011].
What is the paper about?
The paper deals with two herbicides, glyphosate and glufosinate ammonium that are sprayed on both genetically modified (GM) and non-GM crops, and an insecticidal protein Cry1Ab that is produced by the naturally occurring soil bacterium Bacillus thuringiensissub sp.kurstaki (Btk). The gene encoding this protein has been used to genetically modify some crops so that they contain the protein and are thus protected against certain insect pests. The protein is also extensively used in organic and conventional farming as a direct application pesticide
The authors of the study claim to have detected the Cry1Ab protein in the blood of pregnant and non-pregnant Canadian women, and in umbilical cord blood of foetuses.What are the concerns about the paper?
A number of methodological and interpretive limitations of this paper limit the relevance of the reported findings and conclusions about food safety. The key limitations include insensitivity of the assay method used and unsubstantiated and invalid assumptions regarding the source of the Cry1Ab protein in the diets of test subjects. Media speculation arising from this paper has also presented conclusions about the human health relevance of this paper which are not supported by either the paper itself or the broader scientific literature. These issues are discussed in more detail below.
The assay method
The assay method (ELISA) used for Cry1Ab protein was not tested (validated) for its suitability to measure Cry1Ab in human blood. Other reports in the scientific literature have shown that the ELISA assay is not suitable for this purpose.
In mammals, the Cry1Ab protein is degraded in the stomach. If any fragments of the Cry1Ab protein were to pass through into the blood stream, they would be present at levels much lower than could be quantified by the assay method used in the study.
The assumption that GM foods are the source of the Cry1Ab protein
The authors do not provide any evidence that GM foods are the source of the protein. No information was gathered on the diet of any individual in the study so the assertion that the detection of Cry1Ab is linked to ingested GM food is, at best, speculative.
Several insecticidal formulations (e.g. Delfin, Dipel) contain a blend of crystallised proteins, (including Cry1Ab) and livingBtkspores that germinate into the bacterium that then produces the proteins. These formulations have been applied worldwide, including in Australia, for decades. They are applied to crops such as broccoli, cauliflower, celery, melons, potatoes, spinach, tomatoes, cucumbers, turnip, grapes, kiwi-fruit, citrus, avocados. They are used both commercially and by home gardeners and are permitted for use on organically-certified crops.
In comparison, the consumption of food derived from GM corn containing the Cry1Ab protein (no other currently commercialised GM crop species contain this gene) is recent and relatively minor. The corn lines containing the Cry1Ab protein are mostly used for animal feed and for processing into refined products such as corn syrup and corn starch which, because of processing, contain negligible levels of any protein. None of the GM corns produced so far are popcorn or sweetcorn lines and are therefore not consumed directly. Therefore, ingestion of Cry1Ab by humans via GM corn is not likely to be significant compared to conventional and organic produce sources.Interpretation by the media that Cry1Ab protein is a human safety issue
There have been claims in the media that the paper is proof GM foods are not safe for human consumption.
However, the paper does not discuss the safety implications of finding Cry1Ab in the human body and the authors make no mention of any abnormalities in either the subjects or, in the case of those who were pregnant at the time of the study, the subsequent process of birth or the health of the mothers and babies postpartum.
The Cry1Ab protein, whether ingested via Btk-sprayed conventional or organic crops or GM corn products containing the protein, is safe for human consumption at the levels likely to be found in these sources.
For more information, see this report , prepared under the auspices of the World Health Organization. It is about Bacillus thuringiensis, the organism used in the spray formulations, and from which various genes have been isolated for use in genetically modified crops. Chapter 7 deals with a whole range of exposures to the organism (and hence, the proteins produced by it) and their effects in humans.
See also later post: Many sources of Bt in addition to GM crops
PDF 
This post was syndicated from GMO Pundit. You may comment here or on the original entry.
David Tribe is an applied geneticist, teaching graduate/undergrad courses in food science, food safety, biotechnology and microbiology at the University of Melbourne. 
Here’s a question that begs for an answer: is it possible for a person to gain a degree in science without knowing the fundamentals of designing a meaningful experiment?
If the answer is ‘no’, then people like Aziz Aris and Samuel Leblanc, and studies like this, are concocting propaganda in their labs.
There is of course another interpretation. Likely we all remember the work Losey did with Bt and Monarch butterflies. Come up with scary crap and more funding for research arrives post haste. Which would mean there’s something fundamentally wrong with how research funds are allocated.
Unfortunately, Greenpeace is known to pay for research, and to get the results they pay for. Which is also quite bad. Seralini et al junk science results from activist funding.
Absolutely – particularly in areas in which they aren’t trained (Molecular biologists doing toxicology, as an example)
The following was stated by David Tribe in the introduction:
The actual statement in the paper (in the introducion) is.
Please note that the actual article does not state that all of the Bt came from directly eating only corn.
Thus, the argument by David Tribe that it could not have come from direct eating of only Bt corn is what is known as setting up a “straw man”.
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It does state in the Discussion Section the following :
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I interpret point number one as indicating that the authors feel that the Bt may have accumulated from a number of food sources.
The second possibility listed is that it came from contaminated meat, I feel that that possibility needs a literature citation. I did a quick check of the beef Bt literature, and it appears that a good case could be made (from existing literature) that it did NOT come from eating beef.
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I spent some time examining their statement about the contaminated meat, and they mean contaminated by food in the gut of the cattle – akin to meat contaminated by gut bacteria.
Remember that the paper is examining several substances, one of which is Cry1Ab (the test they used also tests for Cry1Ac which they did not mention).
Also, you misrepresented what the article said, it did not say that the authors claimed that it came directly from eating corn – but that it must have come from corn if true.
Hmm. I’ll have to look again later, but at first glance I can’t seem to find the controls. You know, other proteins from plants that you’d want to compare in the blood samples.
I saw the blank, and the spiked stuff, but I mean other proteins in the blood to help us understand the amount getting through to the blood.
MaryM, is it possible that daedalus2u idea about if there was 100% detection that would mean a strong possibility of false positives is why the Editor/reviewers did not insist on a further test for false positives. i.e. was the fact that there were human blood samples that tested negative sufficient to rule out that another human blood protein was responsible?
Regarding Karl Haro von Mogel statement:
Yes, that is what David Tribe is saying, but he is discussing an actual article that does not make that statement. I put in quotes what the actual article states. David Tribe seems to be assuming that no GM products are imported. The original authors are making the reasonable assumption (for Canada) that the pregnant woman were exposed to
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Regarding Karl Haro von Mogel’s statement
Yes, thank you, they do state that
I did not understand the part of the statement
Since, of course the toxin would be in the GM BT crop. What they probably should of said (as you suggest) “raising concerns that the BT in the GM Bt food in the gut could contaminate the meat”. Again, thank you.
The following was stated:
H.Kuska comment: Neither the Agdia web page for this test nor the actual manual mentions a 1 ng / ml detection limit.
From the Agdia manual for this test the following was stated:
Thus it appears reasonable to me that the fact that another lab could not detect a color change below 1 ng / ml, would only apply if the same optical detection system and method was used.
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The article states
I would assume that if the standard curve had a point for 0.1 ng / ml that they actually detected it.
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Also please notice that the 0.04 was an average. From Table 3 the actual numbers are:
Range of detection (ng/ml)
nd to 1.50 and nd to 2.28
AND
Mean ±SD (ng/ml)
0.19±0.30 and 0.13±0.37
Please note, the means are much higher than the stated .04 average.
It appears (to me) that the .04 average included the zero values.
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I am willing to give the authors credit that they observed signals (positives) above the background level. My main question is how do they know that they were not “false positives”? A water blank is not sufficient. Ideally they would need to run the tests on women who ate the same diet but with no GM Bt food and that these tests came out negative. i.e. there may be other molecules that will react positive in something as complex as a human system. (This may be similar to what MaryM is saying.) One this point I agree with David Tribe with the change of his “likely” to “possible” and his “most likely” to “may”:
Correction. Please disregard the 0.04 average discussion regarding Table 3. The .04 “average” is a “mean” from Table 2. Sorry.
As part of the example of setting up a “straw man” argument. One of the points that the original authors made (approved by the reviewers and the editor) is:
yet David Tribe states in setting up his “corn only” analysis the following:
.
No reference(s) is/are given.
It is possible that the reason that the original authors used the words “in humans” is because transfer from the gut may be species dependent. For example “A very low frequency of transmittance to visceral tissue was confirmed in pigs, but not in sheep.”
In addition to pertaining to the bioaccumulate question, this last quote opens up the possibility that the woman were exposed to Bt when consuming contaminated pork.
Regarding the statement:
This is what the Journal states:
It you record noise, you don’t get music – you get rap.
Henry, the Agdia test is qualitative, it is a presence/absence test. The method as described in the manual is not a quantitative method. There is no discussion of using a calibration curve and fitting absorbance readings and then interpolating the results. The authors did not follow the Agdia protocol for the test they used and they used it for something it was not designed to do.
The way the assay works is that there is an antibody that binds the Bt protein to the container. Then another antibody linked to an enzyme is added which binds to the Bt protein now bonded to the container. Then another reagent is added that the linked to enzyme causes to produce a color change. The container needs to be rinsed carefully, and the time for the enzyme to generate the color change needs to be correct. The time the directions call for is to generate a presence/absence test, not to generate a color signal proportional to the quantity of peroxidase enzyme present.
The assay is designed for testing plant materials, seeds and leaves, not animal materials like blood or plasma.
If there are proteins in blood that bind non-specifically to the Cry1Ab antibodies, or to the container, or proteins in blood that act as peroxidases (like hemoglobin, SOD, myeloperoxidase for example), there could easily be false positives. That essentially every sample was positive indicates to me they were very likely false positives.
I agree with the above comments – especially those from deadalus2u. Almost all their signals were extremely weak, and they give no indication that they did any validation of the assay as they used it. (Interestingly, they report limits of detection for all four GC-MS assays, but none for the ELISA).
Some of their numbers from Table 2 make me even more skeptical. They report that 24 of 30 fetal cord serum samples were positive for Cry1Ab. In their methods, they say they used a standard curve from 0.1 – 10 ng/mL. Ordinarily, you wouldn’t attempt to quantify any samples that gave a response lower than the lowest standard. You certainly shouldn’t do that if you haven’t verified the LOQ of your assay.
But even if all 24 supposed positives were right at the lowest standard of 0.1, then the group average would have been 0.08 ng/mL (24×0.8/30). Instead, they report a group average of only 0.04 ng/mL. That means that many of those 24 “positives” must have had numeric values well below 0.1, and even below 0.05.
That sort of thing makes it even harder to have much confidence in the validity of their results.
Very good point. That dissection of the math had not occurred to me yet, as my own analysis has chiefly focused on whether they were above the limit of detection. Limit of detection or not, you cannot use a data point that is outside the range of standards used in your standard curve to quantify anything, let alone outside the linear portion of your standard curve.
Karl Haro von Mogel stated:
H.Kuska comment. It is my understanding that the reason that a calibration curve is used is because detectors are not linear. Also, see my comment about the use of the blank as part of the calibration curve.
daedalus2u, of course, it is being used as you describe but it can be used as part of a quantitation determination as the authors used it (David Tribe in the lead article gave a reference where this particular kit was used as part of an attempted quantitative determination of Cry1Ab protein.)
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I looked at the manual to see if it gave a minimum sensitivy value. I did not expect any as the color intensity can be detected by many spectrospic techniques which vary in sensitivity (in my day a Fourier transform optical spectrometer was probably state of the art sensitivity wise).
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Your statement:
H. Kuska comment: I am confused about what you are basing the above statement about “every sample” on. This is what I read:
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The following was stated:
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H.Kuska comment. I do not know if they used the blank for a .00 extrapolation point. I think that one would have to look at the actual calibration curve to see if the lower concentraions were linear and intersected the blank at zero concentrations (or produced a curve with a very high r(squared) (confidence) value). I would think that they had to determine the LOQ (limit of quantitation – concentration at which quantitative results can be reported with a high degree of confidence) as they did conclude that some readings had to be reported as as “not detectable”. I agree it would of been nice if they had presented more raw data and more detail about the data work up but as I mentioned in another thread:
Of course, this study got circulated via listserv by one of the sustainable ag profs at ISU, with no skepticism of the findings. So frustrating.
Anastasia Bodnar, I did not find in this thread any comments from you concerning which of the findings you feel merits frustration. Perhaps if you present them, I and/or someone else may either explain why they said what they did or benefit from your points.
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This is their Conclusion section.
The Editor/reviewers allowed
They are the independent experts and had the ability to correspond with the authors on unclear points and material not appearing in the manuscript. The established scientific way to challenge an article is to send in a follow-up article or communication/letter to the same journal. This allows the editor and original authors a chance to either explain whatever points you feel are deficient or to agree with them.
I found the following article concerning the demand for extra extensive experiments before publication versus the advantage of getting the research available to the scientific community to stimulate further research by others interesting (I had not considered this point of view).
http://www.nature.com/news/2011/110427/full/472391a.html
Another odd part which seems to get no mention – it appears that pregnancy eliminates glyphosate from the blood. This then warrants no further mention – when you look into it only 2 of the non-pregnant women had detectable glyphosate despite the mean being 73.6 and the standard deviation being 28.2 – this would suggest monsterously high levels of glyphosate in 2 of the subjects (greater than 1ug/ml – which is what one would expect if exposed to 400mg/kg glyphosate orally within the last 24 hours (or last 10 minutes..) – which amounts to 24g of glyphosate for an average woman) – the numbers are also funky – I can’t see how one would get an SD of only 28.2 in a group of 39 subjects with a mean of 73.6 where only two subjects had non-zero values (of ~1500) – the SD should be in the region of 200+
The other notable mention in the paper is that the levels they detect show absolutely no correspondance with levels which induce issues in rats – it strikes as somewhat odd that they therefore do not conclude that there should be no worries, what with the detected levels being vastly below what might be expected to cause harm – rather the conclusion is that their own levels should be used as reference points – which may well be the case, but if so it should be made explicit that in all the literature regarding adverse effects of the chemicals studied their reference levels would have turned out as having no effects.
On limits of detection and calibration curves – it is simple standard practice not to report results lower than your lowest concentration on a calibration curve – regardless of whether you have a blank of 0 and an apparently linear graph, if you end up with lower concentrations one would think you’d simply redo your calibration curve to cover the actual range you find.
Concerning Ewan R’s May 2, 2011 at 8:37 am comments about the glyphosate part of the paper. It was my understanding that David Tribe was discussing only the Cry1Ab part of the paper at present.
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Ewan R’s May 2, 2011 at 8:37 am comment about exposure in a short time seems to also be assuming no bioaccumulation as did David Tribe in the original article. I requested documentation for that assumption but have not received any. I did provide documentation for Cry1Ab being detected in pig muscle.
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Concerning Ewan R’s May 2, 2011 at 8:37 following comment:
H.Kuska comment. Unfortunately the mode of action, results, etc. cannot always be predicted from rat or mice studies. In fact sometimes the rat and mice studies are not supportive of each other. (Another example of Nature is complex).
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The following Ewan R’s May 2, 2011 at 8:37 comment:
H.Kuska comment. No documentation was given for the above “standard practice” The reviewers and editors accepted the procedure and I am not aware of of this inability to use the zero concentration point in a calibration cure using the “protections” that I mentioned earlier. Of course one could not do this if there was reason for suspecting a phase transition, dimer formation, etc. in the range below .10 and .00, but it appears that neither the authors, reviewers, nor editor felt that something like that applied.
Consider the discussion expanded. The paper is full of erroneous nonsense, I decided to discuss another aspect.
Bioaccumulation in my post refers to glyphosate, so references to cry in this are meaningless.
Unfortunately the mode of action, results, etc. cannot always be predicted from rat or mice studies.
Editors and reviewers for toxicological studies repeatedly accept rat data, I would suggest perhaps you write a letter to the various toxicological journals expressing your incredulity that they’d continue to use rat models. I await the results with trepidation.
Because it is standard. It has been highlighted above that this was unexpected. Given the other absolute howlers that made it into the paper I think we can expect that the editors and reviewers were not on their A game the day this paper came to light, your persistent return to the “but the editors and reviewers…” is disingenuous, tiring, and a block to any sort of discussion.
Regarding standards using the blank data. This is from A google search:
I have a question (actually a couple):
Is there any reason to assume that the Bt-originated protein is anything other than inert in humans? That it has a particular effect on certain insects does not, to me, indicate that, to humans, it is a “toxin.” (I hate the use of “scare words,” and the language of this study, along with its particular choice of human subjects, seems intended to create emotional impact.)
Also, if some proteins can enter the circulation from the gut, other than this Cry, it seems a pretty ordinary result, not worthy of words like “contamination” or “[high risk of] exposure” since those terms are very likely to be understood differently in everyday speech than in a technical discussion. I’m willing to bet that many other proteins or peptides of plant, animal and bacterial origin also cross the barriers, and we don’t freak-out about that normal occurrence. Again, what’s so special about Cry that we should especially worry about it? I believe that the use of it (or related proteins) directly as a pesticide has received quite a bit of attention; if it’s been found to be unconcerning in that context, then why should it be concerning in this one? (David touched on this at the beginning of the original post.)
What about all those _unexamined_ and _unknown_ proteins from the test subjects’ gut bacteria, from the yogurt, meat and vegetables they eat, and worse, what if there was an accidental leaf from a not-recognized-as-edible weed that accidentally got included in someone’s green salad?
The question was asked:
H.Kuska comment. The following very recent paper does not yet appear on Google Scholar. It does suggest that the Bt protein may not be inert.
I cannot paste the abstract or pertinent sections) here as for some unknown reason I have lost the ability today to copy and paste from a PDF document. Here is the full scientific reviewed publication in PDF form.
Please use your PDF “Find” command (not your browser’s Find command) with the keyword “human”.
http://www.jstage.jst.go.jp/article/bbb/75/2/305/_pdf
Which leads us to a section which tells us that there is a similar fold utilized by proteins for various things with varying substrate specificity, one of which proteins is human – tells us nothing about the inertness or otherwise in humans (whereas the literature is replete with instances where Bt proteins have no adverse effect)
Setting up straw men Henry?
Ewan R I am sorry that you do not interpret that my cited paper is indicating what I stated:
I should have added “in humans”. Since that was the topic I apparently did not feel it necessary.
The only piece about humans says nothing about whether or not it would be inert – it highlights an interesting aspect of Cry protein structure in that there are folds which are represented across various binding proteins with different specificities.
Part of Ewan’s original comment on May 2, 2011 at 8:37 am was:
H.Kuska comment. If this is a non Cry1Ab based point, then I will not discuss it further in this Cry1Ab thread. If it is a Cry1Ab point, please provide a reference for the rat studies that you are referring to.
It’s about roundup, the post in general is about the study, only in the linked post (so your disparaging David Tribe is a marvellous straw man as you should be disparaging Kuntz) is the discussion limited to cry proteins – I was simply reinforcing that the study itself is clearly flawed by looking at another aspect. You could simply not respond rather than attempting to weasel your way out of a response on a technicality that makes no sense in a situation where a broader topic is clearly open for discussion (ie the fact that the paper is full of holes)
The following was stated:
H.Kuska comment. The forum Comment Policies states:
I.E. I did not state that I could not respond. Please only discuss what I actually state.
Writing fail I guess. When I stated “you could not respond” I meant rather that you could take a course of simply not responding, rather than implying that you physically couldn’t respond to the point.
Actually the word failure was mine. Your actual statement included the word “simply” which should have made the meaning clear to me. The reason I brought up the “Conjecture, nonsense, and conspiracy theories rule” is the rest of your statement
I am honoring what I feel is the author’s restriction/wish. It had nothing to do with an “attempting to weasel”
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My earlier statements were:
I then quoted the following notice at the beginning of the thread (by whoever the actual author is):
AND later
I stated:
This part of the discussion is getting silly. I did not read Ewan’s comment as being a statement that you were unable to respond, instead it was a suggestion that you had the option of not responding. Second, the reference to comment policy is outright silly here.
The statement about “Only claims of Aris and Leblanc on Cry1Ab are discussed here for the time being.” is from the original article by Kuntz and is not an instruction to only talk about Cry1Ab in the thread. Also, Marcel Kuntz name is clearly posted at the top of the pasted article, so there should be no confusion as to who wrote what.
Karl Haro von Mogel stated:
H.Kuska reply. Well, you are an administrator and if comments like
and your above comment are considered appropriate in this scientific discussion based forum, then I am leaving this forum.
I had stated
Ewan commented:
The following very recent review appears to address this question:
“A Critical Review of the Effectiveness of Rodent Pharmaceutical Carcinogenesis Testing in Predicting for Human Risk”
Unfortunately, only the abstract is available to the public Here is some quotes from the full paper:
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I could give many more but this is probably already too long. Of course one could say that this only applies to cancer studies, but in my general reading this has happened in many areas of toxicological testing. If someone wishes to cite documentation(s) that my statement is incorrect, please do and I will examine it/them.
It would be a grave error to believe that rats are ‘little humans’ when it comes to performing experiments.
Live humans would be better, but testing things on humans is, in some settings, considered unethical.
For instance, there was the test of GM lactoferrin rice to combat diarrhea-related dehydration which used children (in Peru?) who actually had acute diarrhea. If I recall aright, a doctor or two were exiled from the country in lieu of criminal proceedings.
There are similar problems with the Golden Rice situation: it’s far enough along that it would be possible to feed it to children going blind, etc., from vitamin A deficiency to see if it’s efficacious. That, too, is considered unethical.
When you keep bumping your head against these issues, rats looks like pretty much your main option.
The mode of action of Cry Bt proteins is well established for insect pests. If they worked similarly in the human gut, you’d get symptoms similar/identical to stomach ulcers. This is beating a dead horse.
Eric’s statement includes “If they worked similarly in the human gut,”
H.Kuska comment. But is there sufficient evidence to be confident that the Cry Bt proteins will act similarly in both insects and humans to satisfy the requirements of a government safety assessment? I would not expect that a statement containing the word “if” would not be sufficient.
I still cannot cut and paste from the article, please see what it states on page 311 about small animals.
Small soil dwelling animals. Like nematodes. One would think that as this is a Cry5 piece of information you’d keep it out of a discussion on Cry1Ab, consistency y’know?
The literature is replete with information on the mode of action of Cry1Ab – it is labile in the acid environment of the mammalian stomach, it requires cleavage by insect proteases under alkaline conditions found in the insect midgut, and binds to specific insect midgut proteins causing pore formation and perforation (which is either what directly kills the insect, or which leads to systemic infections as Eric has alluded to – this would indeed appear to be the reason that Bt does what it does – rather interesting method of spreading ones progeny)
I worked with Bt constructs in a previous life. My understanding is that these proteins are active at high pH (as in the gut of Leps and Coleops). They are inactive in humans due to the acidic nature of the gut.
Sorry, please remove one of the “not” in: “I would not expect that a statement containing the word “if” would not be sufficient.”
To put some published paper details on the record, I am pasting here some direct quotes from the papers referred to by Marcel Kuntz’ original post:
Chowdhury EH et al. (2003). Detection of corn intrinsic and recombinant DNA fragments and Cry1Ab protein in the gastrointestinal contents of pigs fed genetically modified corn Bt11. J Animal Sci. 81:2546-2551, 2003. “However, because the ELISA or immunochromatography kits and immunoblot did not work for blood samples, the present trial could not determine whether Cry1Ab was absorbed into the blood.”
Lutz, Bodo, Steffi Wiedemann, Ralf Einspanier, Johann Mayer, and Christiane Albrecht (2005)Degradation of Cry1Ab Protein from Genetically Modified Maize in the Bovine Gastrointestinal Tract. J. Agric. Food Chem., 2005, 53 (5), pp 1453–1456. “Two independent sets of gastrointestinal samples revealed the apparent discrepancy between the results obtained by ELISA and immunoblotting, suggesting that the antibody used in the ELISA reacts with fragmented yet immunoactive epitopes of the Cry1Ab protein. It was concluded that Cry1Ab protein is degraded during digestion in cattle. To avoid misinterpretation, samples tested positive for Cry1Ab protein by ELISA should be reassessed by another technique.”
Paul Vijay Kerstin Steink and Heinrich H.D. Meyer (2008) Development and validation of a sensitive enzyme immunoassay for surveillance of Cry1Ab toxin in bovine blood plasma of cows fed Bt-maize (MON810). Analytica Chimica Acta 607:106–113, 2008.doi:10.1016/j.aca.2007.11.022
“A number of ELISA [21–25] and commercial kits (QuantiPlate kit for Cry1Ab/Cry1Ac, Envirologix and DAS ELISA kit for Bt-Cry1Ab/1Ac protein, Agdia) are already existing for the detection and quantification of Cry1Ab protein expressed in GM crops and their by-products. These commercial kits have been also used in various livestock feeding studies on GMO for the surveillance of transgenic protein in the animal tissues and gastrointestinal contents [17–20,26]. Though the commercially available Cry1Ab protein ELISA kits(QuantiPlate kit for Cry1Ab/Cry1Ac, Envirologix and Agdia)were reported to detect Cry1Ab protein down to 1ngmL−1 of spiked blood [L. Petit, F. Baraige, Y. Bertheau, P. Brunschwig, A. Diolez, K.Duhem, M.N. Duplan, P. Fach, A. Kobilinsky, S. Lamart, A.Schattner, P. Martin, J. AOAC Int. 88 (2005)654.], however, the study missed the most important assay validation part. Further, in another study [E.H. Chowdhury, H. Kuribara, A. Hino, P. Sultana, O. Mikami, N. Shimada, K.S. Guruge, M. Saito, Y. Nakajima, J. Anim. Sci.81 (2003) 2546.] the same ELISA kit (Envirologix) did not work for the analysis of blood plasma for the surveillance of transgenic protein. Hence, such commercial kits designed for transgenic protein (Cry1Ab or Cry1Ac) quantification in plant materials warrants for a proper assay validation before used for protein analysis in animal systems.”
“4. Conclusions [Paul et al.]
A sandwich ELISA based on immuno-affinity purified polyclonal native capture and biotin-labeled detection antibody has been developed for the Cry1Ab toxin determination at low levels (CCbeta, 2.3 ngmL−1) in bovine blood plasma. The developed ELISA satisfied the performance and validation criteria laid down by Commission Decision 2002/657/EC. The immunoassay performed well with the spiked plasma samples and recoveries ranged from 89 to 106% (mean value of 98%). When applied for the surveillance of transgenic Cry1Ab toxin from Bt-maize in blood plasma of cows fed transgenic ration for a short-term, no sample was positive for the presence of Cry1Ab protein. Further work can be carried out to apply and validate this ELISA for surveillance of Cry1Ab toxin in blood plasma and other matrices like milk, urine and faeces collected from the animals fed for long-term on transgenic ration. Most probably it could answer questions like digestive fate of transgenic protein and possible entry into the blood stream, if successful in breaking the digestive barrier of animals fed for long-term on GM plant and plant by-products.”
There’s a really bizarre post on Rodale about the Aris paper: Genes from GMO Food Do Wind Up in People, Study Shows
Nevermind that the paper wasn’t about genes…. Here’s the money quote (emphasis added):
As an employee of Agdia, Inc. I want to say that these two papers are very well done. I could not have done a better job. Our Bt diagnostic tests were developed and intended for use in plants period. Any other use is simply not valid and certainly not endorsed by our company.
Thank you for your comment. It is good to have confirmation that the tests are for plant tissue, not mammalian tissue.
Hey y’all, I just found a critique of this post on GM Watch, written by an anonymous scientist.
http://gmwatch.org/latest-listing/1-news-items/13450-scientists-rebut-of-critique-of-bt-toxin-in-human-blood-supply
It completely misses the mark on the issue of whether the kit that was used was appropriate. As indicated by even an employee of the company that made the ELISA kit, it was not designed for use on blood, serum, or anything like that, but instead plants.
Thank you Karl. It never ceases to amaze me how tenaciously even highly educated people will hold to a scientifically untenable point of view. What really worries me is that the mass media might just pick this up and run with it. I find that many times the mass media does not seem care about the truth either.
You’re exactly right. If it bleeds, it leads.
I have updated my profile for those of you who wish to know more about who I am.
Glad to see all you scientist types debating this issue.
[...] Maternal and fetal exposure to pesticides associated to genetically modified foods in Eastern Townships of Quebec, Canada 2011 in Reproductive Toxicolology. This paper has been discussed elsewhere, including by Marcel Kuntz and Food Standards Australia New Zealand, then subsequently on Biofortified. [...]