Trace Minerals & Toxins: GMO Concerns

Why does food grown organically seem to taste better than conventionally grown food. Is this my imagination or due to some real difference? I read that levels of trace minerals (micro-nutrients) were usually lower in non-organic food. This makes sense for hydroponic foods, but why should conventional agribusiness crops have lover levels of trace minerals?

Truthfully, I’ve been somewhat sceptical about health and safety risks from GMO (genetically modified organism) crops? Inserting genes for disease resistance does seem sensible. The Environment Committee of the Connecticut Legislature happens to be reviewing a bill (HB 5117) that would require labeling all such food, so I read Hearing testimony and did some research.

A recognized concern, from a health and environmental standpoint, is the gene that has been spliced into crop plants, for a persistent bacterial toxin (from BT or Bacillus thuringensis). This toxin is now found in the blood of the majority of American women. It is a natural pesticide that attacks cell membranes – not just in the target pest caterpillars, but also membranes in rats and potentially in humans, especially fetuses. However, I did not see any data on toxin concentrations, and information on threshold concentrations for harmful effects is sorely lacking.

Analysis of potential impacts on adjacent ecosystem biodiversity from BT GMO crops has also been wholly inadequate. How will populations of economically insignificant species of caterpillars, moths and butterflies -and their predators- be affected by feeding on leaves and pollen from GMO plants along field edges? Ill effects on migrating monarch butterflies were in the news last year.

I see even less less public concern with the largest category of GMO crops: those with an inserted gene that makes them “Roundup Ready”, able to tolerate its active herbicide ingredient, glyphosate, although application rates must be cranked up several fold. Interference with uptake of micro-nutrients by glyphosate was studied in Stuttgart, Germany, at the University of Hohenheim, over ten years ago. German researchers warned us that mineral-deficient plants would be more susceptible to soil fungal diseases; this is now well documented for many fungal diseases – most recently widespread Fusarium wilt in GMO Roundup Ready soybeans in the southern US. The Stuttgart scientists found two causes of the problem: 1) glyphosate firmly latches (chelates) onto soil trace minerals, making them unavailable and 2) it eliminates or suppresses soil microbes and invertebrates. These include beneficial mycorhizal fungi) which help the plant extract soil nutrients (trace minerals included), and earthworms, springtails, isopods and man other soil organisms that recycle nutrients from plant debris into soil (trace minerals included). [As glyphosate is only one of many agrichemicals that suppress populations of soil organisms, my first question was answered; I can now see a scientific basis for lower levels of trace minerals in non-organically raised foods!

Because Roundup application rates increase sharply when GMO Roundup Ready crops are planted, this micro-nutrient problem has become more severe. Scientists at several US midwestern universities followed the lead of the Stuttgart researchers, including Don Huber at Purdue in Illinois, Barney Gordon in Kansas, and Kurt Thelan in Michigan. They have continued to investigate the trace mineral deficiencies, particularly manganese, but also zinc and others, that are an unwelcome side-effect of Roundup use (glyphosate). [The URL of a review article is It was posted out of Western Illinois University by Enviroadmin on Sunday, 23 May 2010.}

It is now also known that the inserted gene in GMO Roundup Ready soybeans interferes with production of a root secretion that solubilizes minor mineral nutrients. (This is in addition to glyphosate directly chelating micro-nutrients, and suppressing or killing beneficial soil microbes and invertebrates.) Attempts to cope with the problem by fertilizing GMO Roundup Ready crops with heavy dosages of micro-nutrients have been challenged by the chelating (tight-attaching) properties of glyphosate. Similarly, human assimilation of mineral supplements in pill form is usually poor, unless the dietary supplements are bulky and food-derived! I, for one, balk at swallowing horse pills three times a day.

Nor has there been adequate analysis of the impacts on surrounding ecosystems of expanded Roundup use on Roundup Ready GMO crops. How much has it reduced the extent of field edge buffers with grass and forb (“weed”) seeds that used to be available for songbirds? Such buffer strips between and around fields are still available in a sustainably managed organic farm. More and more weeds are evolving resistance to to glyphosate; the response is accelerated efforts to develop GMO crops resistant to other herbicides, that have their own suites of risks and side-effects – which will also not be adequately tested as this is not yet required by EPA.

I can envision genetic modification for the purpose of inserting blight resistant genes from related plant species or perhaps to improve crop quality, but only after far more rigorous testing than is the current practice – directed by a third party entity (not Monsanto Corporation testing its own GMO crops!). But inserting genes for herbicide tolerance – or insecticidal proteins – seems fundamentally unwise. Expansion of organic agriculture is important for the human diet as well as for the surrounding natural environment; not just to avoid possible pesticide residues, but perhaps more importantly, for the sake of nutritional quality.

A version of this post was sent to several Connecticut members of the Environment Committee, and published by CT NOFA (Northeast Organic Farming Association)



About sigrungadwa

Consulting Ecologist and Registered Soil Scientist. My firm, Carya Ecological Services, LLC conducts inventories of vegetation, wetlands, and habitat; wetland delineations; and ecological assessments - for open space grants, application reviews, and applications for open space/cluster developments. We work either as the lead firm or as a subconsultant. I have a Masters Degree from UCONN-Storrs, Dept of Ecology & Evolutionary Biology (1997) & a Bachelors from Brown U. in Biology.
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