Thursday, May 24, 2012

False claims that GM protein Bt is present in mothers' blood and foetus tissues are based on incompetent chemical analysis

In 2011 a paper was published by some Canadian workers examining agricultural pesticide residues in the newborn babies and mothers.

This protein, generally called Bt and also called Cry is present in genetically manipulated crops, and also in biological pesticides used by organic farmers.the claims about its presence in maternal tissues are highly disputed and controversial .

They are however repeatedly quoted by anti-GM campaigners withoutany disclosure of their analytical weaknesses.

The latest set of claims about this paper are being made by the group called Take the Flour Back who are  currently threatening to sabotage a field trial of insect protected wheat being tested in England.

The misuse of thi information about the protein Bt is just one example of the many misleading and scientifically unsupported claims being made by these antitechnology activists.

It is important to understand that the position of the activists in this latest example is largely political.

 They  simply want to sabotage an industry they disagree with.

TTFB have visions of reforming the world food supply system and they feel that their criticisms about this food system is so compelling that they are justified in sabotaging new technical developments occurring that might be used in it.

They appear to be using their threat of sabotage as primarlity a way of gaining media publicity. The sad thing is, major media organisations completely pander to this immoral ploy.

For the he moment let's concentrate on demonstrating the flimsiness of their arguments about biology and food safety.The flimsiness of their pretensions to reform the world food system are worthy of another long discussion

So lets  go back to the  contested study published in 2011 which purports to demonstrate the presence of a protein Bt in tissues of mothers and newborn babies

Very low levels of this detected signal were found and is important to examine the way in which it was detected.

Here is the analytical method from that paper:

Note that have a standard curve where the value 0.1 ng/ml is the low end of the values examined in the assay standard curve

There are more details about the kind of method they are using from the manufacturers:

Note this test is designed to use with plant and leaf material. Aris and Leblanc work with animal (human) tissue. The tests had not been validated in animal tissue and the previous post detailing the validated approach of Paul et al 2007 demonstrates that it should be validated carefully.

Here are some data presented in the Aris and Leblanc paper with actual values for signal detected highlighted for your attention.

Note the values are near the lowest value used on the standard assay callibration curve.

With this sort of complicated test is easy to get low levels of signal from non-specific binding of the reagents used in the assay.

The previous post describes how exacting analysis and careful experimentation is needed to get around the problems of non-specific signal being generated in these assays.

Aris and Leblanc do not even refer to the earlier paper by Paul and others 2007 in which the need to eliminate these uncertainties for valid results to be obtained is fully explained.

In short, Aris and Leblanc report results which are mechanistically implausible because protein in the diet rarely enter the body as intact molecules, and which are highly likely to just represent low-level noise in their complicated assay system.

They should have at least explicitly recognised the limitations of their assay in their paper and warn against the misinterpretation highly preliminary and non-specific signal, because such misinterpretation is obvious to anyone with experimental experience in these assays, or a good training in biochemistry.

The author of this post has that kind of experimental experience and has developed assays using the same kind of technology for other biological components, and even published and patented discoveries made using this technology.