Local Food Ordinances
Bt Study Critiqued
Local Food Ordinances
To the Editor:
ACRES USA magazine (Feb. 2012) had a six-page article on the Local Food Ordinance. So far, nothing at all in recent MOF&Gs. (I checked.) What’s up? This affects us all.
– Betsy Bott, Jeb Bush, Blue Hill, Maine
We ran a news article about the local food ordinance in the Summer 2011 issue of The Maine Organic Farmer & Gardener. Our update for the March 2012 issue did not fit in the print edition – along with many other articles – but is posted on mofga.org.
Bt Study Critiqued
To the Editor:
In a recent editorial, “The Assurance and Power of MOFGA Certified Organic,” Jean English repeats claims made by the Organic Trade Association about Bt corn in order to leave the impression that such corn is harming unborn children:
“… the OTA cites a study by Quebec scientists who found the Bt toxin in 93 percent of maternal and 80 percent of fetal blood samples, and in the blood of 69 percent of non-pregnant women tested.”
The unnamed study is by Aris A, Leblanc S., “Maternal and fetal exposure to pesticides associated to genetically modified foods in Eastern Townships of Quebec, Canada.” From the original report:
“...Cry1Ab toxin was detected in 93% and 80% of maternal and fetal blood samples, respectively and 69% of tested blood samples from nonpregnant women. There are no other studies for comparison with our results.
“To our knowledge, this is the first study to highlight the presence of pesticides-associated genetically modified foods in maternal, fetal and nonpregnant women’s blood.” (Reprod Toxicol (2011), doi:10.1016/j.reprotox.2011.02.004.)
As Skeptic Dr. Harriet Hall cautions, “Never believe one study,” particularly if it is the only such study conducted, and most especially if the authors themselves caution that “more studies are needed, particularly those using the placental transfer approach.”
Other researchers have already begun pointing out some very serious problems with this one study. Immunologist A. de Weck notes: “Regarding the GM protein Cry1Ab, there are many works that directly or indirectly demonstrate that this protein, when ingested orally, ... is not absorbed into the blood, even in minute amounts.” (Quoted in David Tribe’s “If you record noise, you don’t get music – you get nonsense,” featuring a translation of an article with the fabulous title, “Many Women, no Cry,” by Marcel Kuntz. http://marcel-kuntz-ogm.over-blog.fr/article-aris-72793155.html).
In other words, Aris and Leblanc probably did not detect what they claim to have detected because such a claim contradicts the known biology about the Cry1Ab protein in the digestive system.
Even worse, the test used in the study to detect the protein (called ELISA, for enzyme-linked immunosorbent assay) is not even reliable for the uses to which the researchers have employed it. From Tribe again:
“Tests of this kind are particularly likely to yield non-specific false positive findings, especially in the presence of serum.”
Finally, the authors themselves undermine their own claims when they admit that they do not even know the sources of the Bt toxin they have allegedly detected. They ask us to just assume it is from Bt corn.
This is stated in (literally) fine print:
“Our study did not quantify the exact levels of [pesticides-associated genetically modified foods] in a market-basket study. However, given the widespread use of GM foods in the local daily diet … it is conceivable that the majority of the population is exposed through their daily diet.”
In plain English, the authors have made no attempt to determine whether the women tested ate Bt corn, let alone in the quantities necessary to permit detection of the toxin in blood.
Using the logic of the study itself, then, one could say that “given the widespread use of” Bt toxin in organic farming, and given the fact that B. thuringiensis is itself ubiquitous in the environment, “it is conceivable that” these, not Bt corn, are the sources of the toxins the study alleges to have detected in pregnant women’s blood.
Many farmers spray crystallized proteins, live bacterial spores, or combinations of both, on everything from broccoli, to potatoes, to tomatoes, so the actual source of the protein supposedly found in these pregnant women remains entirely in the realm of speculation.
As Dr. Hall cautions, “Roosters don’t make the sun come up”; that is, you can’t assume a cause-effect relationship when one event, in this case “detection” of a toxic protein in pregnant women, follows another, ingestion of GM corn products. But in this case we don’t even know that the rooster crowed!
It takes a lay reader hours to track down, read, comprehend and write about this subject, whereas it takes English only a few minutes to quote an interested party, the OCA, as if it were Holy Writ. This does not inspire much confidence in the thesis of English’s article, that MOFGA “embodies an ethos” that one can “trust.”
– Mike Bendzela, Standish, Maine
Ed. response: We cited the original research when we first reported Aris and Leblanc’s study last summer.
In response to critiques of their work, Aziz Aris says (in Reproductive Toxicology 33 (2012) 122–123 and in a letter in press in Reproductive Toxicology) that studies failing to detect the Cry1Ab protein in blood were done on cows and pigs fed short-term on silage enriched with the Cry1Ab protein – not on humans with different consumption patterns and different digestive systems. Also, false positives of 69 to 93 percent are unlikely.
Regarding use of the ELISA test, Aris says, “The method we have used can easily detect 20 pg/ml (0.02 ng/ml) and can be improved to do more. In addition, our recent results show that the levels of Cry1Ab can reach over what we have published.” In their 2011 paper, Aris and Leblanc provide their calibration curve for detecting the protein from 0.1 to 10 ng/ml.
While the Bt toxin and/or bacteria are applied externally and intermittently on some organic crops, the toxin breaks down rapidly, and bacteria remaining on the crop can be washed off – unlike the Cry1Ab protein in genetically engineered foods. We agree that more independent studies on effects of Bt crops are needed – especially with the increase in Bt sweet corn cultivation. The deficit of independent studies on the safety of GE crops in general for human and animal health is one of the main reasons we are so concerned about them. Unfortunately, restrictive licensing requirements imposed on scientists who want to study GE crops limit the independent research being done in this area. Also, mandatory labeling of GE crops would help with the research because study participants’ diets could be assessed.