Bt and herbicide found in pregnant women
By Jason Major
TechNyou
An article from the journal Reproductive Toxicology is getting a bit of chatter in the online environment with some possible justification.
The Canadian researchers tested pregnant and non-pregnant women for the presence of two herbicides and a Bt insecticidal toxin produced in the GM corn Mon 810.
The one raising most concern in the chatter I have read so far is the Bt toxin which was found in the 93% of maternal and 80% of fetal blood samples. It was also found in 69% of non-pregnant women.
Rationale
The point of this research was to provide some baseline data about the levels of these environmental chemicals in our systems, and to see if they can cross from mother to fetus, which they appear to do.
What it doesn’t reveal
What the paper does not investigate is the biological implications of this. That is, just because an environmental chemical is present doesn’t mean it will have a biological effect. This remains to be determined, by others.
The other important point that any toxicologist will tell you is that it is the dose not the toxin that is imperative. The levels of the Bt toxin measured were 1.5 nanograms per milliliter in pregnant women and 0.13 nanograms per milliliter in non-pregnant women. The question is if there is any level of toxicity or health implications to the woman or fetus, at what dosage does this occur?
As far as I am aware the toxic effect of the various Bt toxins used in GM crops are specific to certain insect groups. Specific Bt proteins are selected to target specific insect pests. The active form of the Bt protein binds to a protein receptor found on cells in the gut of these insects. Other animals do not have these protein receptors, hence the Bt proteins should have no toxic affect – with the emphasis on should.
Stuff left hanging…
The other question left open and unanswered is why there was such a huge discrepancy in the presence and amount of Bt in pregnant and non-pregnant women. 93% of pregnant women had detectable levels of the Bt protein versus 69% of non-pregnant women; and pregnant women had Bt levels of 1.5ng/ml versus 0.13ng/ml for non-pregnant women, which is greater than 11 times more Bt found in pregnant women. The number of women tested were low (between 30 and 40 for each group), but not that low I would have thought to produce such dramatic differences. No explanation was given by the authors as it was possibly outside the scope of the paper, but I would have thought it worth investigating as it appears to be a strange anomaly to me – not that I am a toxicologist.
Bt proteins are relatively new environmental chemicals that humans are being exposed to so we should be careful about how we use them and assess what, if any human and environmental health implications it might have. If there is some adverse affect, human health aside, it will no doubt upset a lot of people, including industry (who have lots of $$ invested in the technology behind Bt crops) and organic farmers because Bt is an allowable insecticide for use on organic farms. Many home gardeners use it as well. I have a small packet at home myself.
The paper
Aris A, Leblanc S. Maternal and fetal exposure to pesticides associated to genetically modified foods in Eastern Townships of Quebec, Canada. Reprod Toxicol (2011), doi:10.1016/j.reprotox.2011.02.004
Abstract – can be found here
Pesticides associated to genetically modified foods (PAGMF), are engineered to tolerate herbicides such as glyphosate (GLYP) and gluphosinate (GLUF) or insecticides such as the bacterial toxin bacillus thuringien- sis (Bt). The aim of this study was to evaluate the correlation between maternal and fetal exposure, and to determine exposure levels of GLYP and its metabolite aminomethyl phosphoric acid (AMPA), GLUF and its metabolite 3-methylphosphinicopropionic acid (3-MPPA) and Cry1Ab protein (a Bt toxin) in East- ern Townships of Quebec, Canada. Blood of thirty pregnant women (PW) and thirty-nine nonpregnant women (NPW) were studied. Serum GLYP and GLUF were detected in NPW and not detected in PW. Serum 3-MPPA and CryAb1 toxin were detected in PW, their fetuses and NPW. This is the first study to reveal the presence of circulating PAGMF in women with and without pregnancy, paving the way for a new field in reproductive toxicology including nutrition and utero-placental toxicities.
From discussion
On the other hand, Cry1Ab toxin was detected in 93% and 80% of maternal and fetal blood samples, respectively and in 69% of tested blood samples from non-pregnant women. There are no other studies for comparison with our results. However, trace amounts of the Cry1Ab toxin were detected in the gastrointestinal contents of livestock fed on GM corn [38–40], raising concerns about this toxin in insect-resistant GM crops; (1) that these toxins may not be effectively eliminated in humans and (2) there may be a high risk of exposure through consumption of contaminated meat.
Additional perspectives
David Tribe has posted commentary from Marcel Kuntz about the paper. Both Tribe and Kuntz suggest the paper is flawed and leaves too much unanswered.
Other references on Bt
The web site Biofortified has a list of independent peer-reviewed papers, many of which include research involved the use of Bt crops