The science is not so simple

2013-07-25 00:00

IN terms of the discussion regarding the safety of genetically modified crops, it is important to realise that in science “the absence of evidence, is not the evidence of absence”.

Furthermore, no single study can prove safety, or for that matter, that something is unsafe. Science is patient and relies on the body of evidence generated by different researchers over a period of time.

When considering the issue of the safety of herbicide-tolerant genetically modified crops, it is important to remember that studies to determine that glyphosate (or any herbicide) is safe were undertaken under the context of a different application prior to the introduction of herbicide-tolerant GM crops.

The original use for glyphosate was as a pre-emergence herbicide. And in this context the glyphopsate was not intended for application on the plant.

With the advent of GM herbicide-tolerant crops, the glyphosate is applied to and taken up by the GM plant. Is this important? We don’t know, but several studies have shown that (in contrast to Hans Lombard’s rhetoric of June 25) effects of glyphosate have been seen in mammals, Nile tilapia and sea urchin.

The response to this has been an industry-sponsored review of glyphosate that not surprisingly concludes that “the available literature shows no solid evidence linking glyphosate exposure to adverse developmental or reproductive effects at environmentally realistic exposure concentrations”.

But the authors fail to explain away all the effects, so add: “Although toxicity was observed in studies that used glyphosate-based formulations, the data strongly suggests that such effects were due to surfactants present in the formulations and not the direct result of glyphosate exposure.” In other words, “because we say so”.

I have no problem with the use of herbicides in a controlled and responsible manner, but to imply that these pose no threat to human health or the environment is ridiculous. Lombard states: “More than 700 scientists around the world have refuted the study [French scientist Gilles-Eric Séralini’s study in 2012] as flawed. They challenged Séralini to come clean and release his experimental data to scientists for evaluation, which he has refused to do.”

This is quite amusing since no biotech company makes the raw data it used to prove the safety of GM crops available either — unless compelled to do so by a court of law — citing it as “confidential business information”. Secondly, the body of “informed scientists” that attacks any study remotely suggesting a negative impact of GM are deafeningly silent when “flawed” studies conclude the opposite.

One example of this is the study by Cromwell et al. 2002 (titled “Soybean meal from Roundup Ready or conventional soybeans in diets for growing-finishing swine”) in which the authors conclude: “This study clearly demonstrates that genetic modification of soybeans to make them tolerant to glyphosate herbicide does not affect their nutritional composition or the performance of swine when fed the soybean meal derived from the soybeans.”

And what did they do to substantiate such a very conclusive statement? They basically fed pigs GM and non-GM soya, respectively, then checked the amount of back fat and size of the loin from which chops were cut, cooked and eaten by “an experienced sensory panel”. Oh, and they also determined the composition of the soya bean meal and crude composition of the loin (water, protein, fat and ash) to be able to conclude that GM soya beans do not affect “the performance of swine”.

I can hear the body of “informed scientists” sing: “but this is only one study, what about all the others?”

Yes, what about the others? Why don’t you attack all flawed studies instead of only choosing those that do not support your viewpoint? Human nature, I guess. A recent study by Thongprakaisang et al. (2013) (titled “Glyphosate induces human breast-cancer cell growth via estrogen receptors”) concluded: “Furthermore, this study demonstrated the additive estrogenic effects of glyphosate and genistein which implied that the use of glyphosate-contaminated soybean products as dietary supplements may pose a risk of breast cancer because of their potential additive estrogenicity.”

Does this mean that glyphosate residue in GM herbicide-tolerant soya beans will cause breast cancer? No. But it does mean that more research is needed to understand the importance of this finding before the research is dismissed by the “informed scientists”.

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