I am frequently subjected to mild scoffing from my scientist/scientific friends, because I want GMOs to be labeled. They pooh-pooh me and say there is no evidence that GMOs are harmful. I argue that there is also no conclusive proof GMOs, either in total or by plant, are safe for human consumption. I also point out that, contrary to myth, there ARE studies showing harm resulting form eating GMO crops. There is scientific peer-reviewed evidence that GMO crops are harmful to animals and there is similar evidence that GMO crops are not harmful.
You would think scientists only had access to half the data on GMOs. When discussing the safety of eating GMO’s, scientists who support GMOs maintain that they:
“have established that the level of safety to consumers of current genetically engineered foods is likely to be equivalent to that of traditional foods. At present, no verifiable evidence of adverse health effects of BD foods has been reported, although the current passive reporting system probably would not detect minor or rare adverse effects or a moderate increase in effects with a high background incidence such as diarrhea.”
That’s great, except for part where they are wrong. The fact is that there IS verifiable evidence of adverse health effects. For one thing, “A study published in 2009found clear negative impact on liver and kidney function in rats consuming GM maize varieties for 90 days” (Key S, Ma JK, Drake PM. Genetically modified plants and human health. J R Soc Med 2008; 101(6): 290-8.) These are not anecdotal findings by fringe tree-huggers; these are peer-reviewed studies with replicable data.
Moreover, all GMOs are not the same type of GMO and it may be that growing GMO crops are causing a “perfect storm” of effects based on clustered – not individual – data sets. No one is really, really certain; there are simply not enough studies yet. Call me a bluff old traditionalist, but I would like the option of avoiding foods that have not be conclusively proven (not just “likely”) to be non-harmful.
However, there is one thing that we can be fairly sure about – the Monsanto created herbicide glyphosate, AKA Roundup, is bad news. GMO crops sold by Monsanto are modified to be “glyphosate resistant”, enabling farmers to spray hellish amounts on their fields yet only kill the weeds. The glyphosate sticks to the food and if you eat “conventional” food, then you get to eat a dollop of Roundup with every bite. Monsanto researchers assure us that Roundup is safe for humans, but non-Monsanto funded research indicated otherwise. In tests of the glyphosate, and not just the individual chemical composing glyphosate, researchers found that “Despite its relatively benign reputation, Roundup was among the most toxic herbicides and insecticides tested. Most importantly, 8 formulations out of 9 were up to one thousand times more toxic than their active principles. Our results challenge the relevance of the acceptable daily intake for pesticides because this norm is calculated from the toxicity of the active principle alone. Chronic tests on pesticides may not reflect relevant environmental exposures if only one ingredient of these mixtures is tested alone.”
Multiple studies have shown glyphosate’s ill-effects on animals. Just recently, yet another study has been added to the fold. When sows were given feed containing Roundup residue (i.e conventional feed) the rate of piglet malformations increased significantly. The authors of the study noted that this was not a fluke:
“The predominant uses of glyphosate are for stubble management, pre-sowing weed control and pre-harvest application (desiccation) . Glyphosate is also used for weed control in fields of genetically modified (GM) crops like soybean, rapeseed, corn, cotton, sugar beets, alfalfa, etc, where it is directly applied to the plants . The rapidly growing problem of glyphosate-resistant weeds is reflected in a steady increase in the rate of glyphosate used on crops. Stems, leaves and beans of glyphosate resistant soy are contaminated with glyphosate. Moreover, because of the extensive use of glyphosate, it is frequently detected in water, rain and air [4,5]. Recently, glyphosate residues were tested in urine and different organs of dairy cows as well as in urine of hares, rabbits and humans in different concentrations . Glyphosate and its commercial herbicides severely affect embryonic and placental cells, producing mitochondrial damage, necrosis and programmed cell death with doses far below the used agricultural concentrations. Paganelli et al.  found congenital malformations in chicken embryos with glyphosate at a concentration of 8-12 μM glyphosate in the injected side. The molecular phenotypes were correlated with a disruption of developmental mechanisms involving the neural crest, embryotic midline formation and cephalic patterning induced by the active principal of glyphosate not by the adjuvants due to impairment of retinoid signaling. The authors gave an overview of reports of malformations in children of families living few meters from where this herbicide was sprayed. The risk of malformation in human embryos is very high when their mothers are contaminated at 2 to 8 weeks of pregnancy. The detected glyphosate concentrations in organs, gut walls and meat of these piglets suspect correlation to glyphosate. Daruich and co-workers  concluded that glyphosate causes various disorders both in the parent female and in the progeny. Paternal exposure to glyphosate is recognized to be a cause of birth defects by pesticide mediated alterations of germ cells [9,10].”
Clearly farm animals are effected by Roundup residue, but what about humans? Bad news there, I’m afraid. Studies have shown that “glyphosate was significantly higher in urine of humans with conventional feeding. Furthermore, chronically ill humans showed significantly higher glyphosate residues in urine than healthy population. The presence of glyphosate residues in both humans and animals could haul the entire population towards numerous health hazards, studying the impact of glyphosate residues on health is warranted and the global regulations for the use of glyphosate may have to be re-evaluated.” (Krüger et al., J Environ Anal Toxicol 2014, 4:2)
Mysteriously, almost all the studies showing glyphosate’s harmful effects have taken place outside the USA. These studies are NOT subject to attempted replication in the USA after publication. It is almost as if Monsanto controls what scientists are allowed to test. American scientists continue to insist that, based exclusively on published information in American scientific journals, that there is no evidence to suggest GMOs are harmful.