Genetically Engineered Crops – Why Scientists are Worried

November 29th, 2013

Novel DNA Spreads into the Environment, Livestock and Humans

By Pamela Coleman, PhD
Farm and Food Policy Analyst
The Cornucopia Institute

gmosunsafe

The food in grocery stores today is unlike the food eaten by our ancestors, even a few hundred years ago.  Part of the difference is easy access to highly processed foods that contain refined sugar and chemical preservatives.  A more significant difference is the high percentage of genetically engineered (GE) crops that are the source for our food.  The corporations who developed this technology tell us that it’s safe, so why are independent scientists worried?

There are many reasons for concern.  The GE crops are created by using a new genetic process to insert an unknown amount of DNA that has the potential to spread in the environment in unpredictable ways.  Independent research on the effects of eating these new foods has been suppressed when it shows evidence that the GMOs are harmful to health.

Novel genetics

Traditionally, humans have bred new varieties of plants by transferring pollen between two plants of the same type, for example from one corn plant to another.  This mimics the exchange of DNA (genetic material, or genes) that occurs naturally without human intervention, and the resulting plants contain only plant DNA.

Genetic engineering (GE) is fundamentally different, because it uses a microorganism (typically a bacterium) to transfer DNA and insert it into the DNA of the plant.  The new DNA contains the desired gene (such as herbicide resistance), plus a gene for antibiotic resistance, plus an unknown amount of bacterial DNA with unknown functions.  The process is not at all precise, partly because the process causes mutations in the plant’s DNA, and partly because even a single change in the plant DNA can give rise to multiple changes other than the one intended.

Spread of engineered DNA

In 2012, GE crops were planted worldwide, on 25 million acres of land.  After GE DNA is released into the environment through the planting of a GE crop, the DNA can spread through the environment to plants, fungi, bacteria, and animals, in ways that are difficult to predict and impossible to control.

It is well known that GE DNA can spread from plant to plant, through the transfer of pollen from a GE crop to non-GE plant, a process called cross-pollination.  For example, GE corn can contaminate non-GE corn, and GE sugar beets can contaminate organic spinach, because they are closely related.  This is a huge concern among seed producers and organic farmers, because the seeds of the cross-pollinated crops, and all their offspring, are contaminated by the GE DNA.  When GE canola transferred its glyphosate-tolerance genes wild mustard this new DNA was able to persist in the weed populations for six years.[1] (Glyphosate is the active ingredient in Monsanto’s Roundup herbicide.)

Less well known is the transfer of GE DNA from plants to bacteria.  In the soil environment, the GE DNA can persist in the soil for at least a year,[2] where it can be taken up by natural soil bacteria and be incorporated into their genomes.[3]  This spread would not be detected in the initial field tests of GE crops, because it is rare, and scientists were not specifically looking at this type of environmental contamination.  As GE crops become widespread and are planted repeatedly for many years, the likelihood increases that GE DNA will spread to soil bacteria.

GE DNA can also be transferred to the bacteria that inhabit the human digestive system.  After volunteers ate just one meal of GE soy, bacteria in their digestive systems contained the DNA from the GE soy foods.[4]

The GE DNA has not only been found in the bacteria, it can also be transferred directly into animals.  When livestock were fed GE crops, the GE DNA was taken up by the animal’s organs and detected in the meat, milk, and fish that people eat.  [5][6][7][8][9]

Questionable research

The uncontrollable spread of GE DNA is a huge issue, in part because of the limited information on the long-term health effects of these novel crops.

Biotech companies claim that genetically engineered crops have been well-researched, and have been proven safe for humans and animals, but independent scientists dispute that claim.  In October of 2013, more than 230 scientists signed the following statement: “We strongly reject claims … that there is a ‘scientific consensus’ on GMO safety.”[10]  (Read the full story here.)

Industry studies have been conducted by the corporations themselves, without review by independent scientists, and the data may not be available for public access.[11]  This process is very different from the accepted scientific standard, where all results are first reviewed by peers (knowledgeable scientists who did not conduct the study) before it is published.

The studies that are available are often inadequate.  Feeding studies are conducted on laboratory animals for only a short period of time – often 30 to 90 days.  Food that does no detectable harm in 90 days may be quite harmful when eaten over the decades of a

human lifespan!  Long-term studies are not required by regulators anywhere in the world.[12]

Independent scientists who have conducted longer-term feeding studies over the lifespan of the lab rats, typically two years, have raised serious concerns about the health effects of GE crops.  Even over this shorter time period, scientists reported harm to the liver, kidneys, digestive and immune systems, as well as other health problems.[13][14]

Industry response has been to discredit these independent scientists, rather than to support peer-reviewed research.  Monsanto discourages farmers from research, by requiring them to sign a “Stewardship Agreement,” which states:  “Grower may not conduct research on Grower’s crop produced from Seed other than to make agronomic comparisons and conduct yield testing for Grower’s own use.” 

In 2009, 26 scientists were so concerned about the suppression of research on GE crops that they made a formal complaint to the US Environmental Protection Agency. They wrote, “No truly independent research can be legally conducted on many critical questions involving these crops.”  Said one scientist: “If a company can control the research that appears in the public domain, they can reduce the potential negatives that can come out of any research.” [15]

Millions of acres of genetically engineered crops have been planted and incorporated into our foods, with little understanding of their health effects.  This opened a Pandora’s box, as the unique bacterial genes spread to other plants, bacteria, and animals.  Independent scientists are being prevented from testing the raw ingredients in our nation’s food supply, even as more and more acres are being planted to these untested crops.  Meanwhile, the corporations who tell us that biotech crops are safe can reap huge profits from the sale of GE seeds.

Many consumers are employing the Precautionary Principle — avoiding GE foods as much as possible until research proves that they are safe.  The best options are certified organic food or purchasing directly from farmers who raise non-GE crops.

This story originally appeared in The Cultivator, The Cornucopia Institute’s quarterly print publication available to members and online.


[1] Warwick SI,et al.  2008.  Do escaped transgenes persist in nature? The case of an herbicide resistance transgene in a weedy Brassica rapa population. Mol Ecol. 17(5): 1387-1395.

[2] Lerat S, et al. 2007.  Quantification and persistence of recombinant DNA of Roundup Ready corn and soybean in rotation. J Agric Food Chem. 55(25): 10226-10231.

[3] Pontiroli A,et al. 2007.  Fate of transgenic plant DNA in the environment. Environ Biosafety Res. 6(1-2): 15-35.

[4] Netherwood T, et al. 2004.  Assessing the survival of transgenic plant DNA in the human gastrointestinal tract. Nat Biotechnol. 22(2): 204–209.

[5] Tudisco R, et al. 2010.  Fate of transgenic DNA and evaluation of metabolic effects in goats fed genetically modified soybean and in their offsprings. Animal. 4: 1662–1671.

[6] Ran T, et al. 2009.  Detection of transgenic DNA in tilapias (Oreochromis niloticus, GIFT strain) fed genetically modified soybeans (Roundup Ready). Aquaculture Research. 40: 1350–1357.

[7] Chainark P, et al. 2008.  Availability of genetically modified feed ingredient: investigations of ingested foreign DNA in rainbow trout Oncorhynchus mykiss. Fisheries Science. 74: 380–390.

[8] Sharma R, et al. 2006.  Detection of transgenic and endogenous plant DNA in digesta and tissues of GMO sheep and pigs fed Roundup Ready canola meal. J Agric Food Chem. 54(5): 1699–1709.

[9]Mazza R, et al. 2005. Assessing the transfer of genetically modified DNA from feed to animal tissues. Transgenic Res. 14(5): 775–784.

[10] On 10/21/2013, ENSSER (European Network of Scientists for Social and Environmental Responsibility) issued the following statement:

“As scientists, physicians, academics, and experts from disciplines relevant to the scientific, legal, social and safety assessment aspects of genetically modified organisms (GMOs),[1] we strongly reject claims by GM seed developers and some scientists, commentators, and journalists that there is a ‘scientific consensus’ on GMO safety[2] [3] [4] and that the debate on this topic is ‘over’.[5]  We feel compelled to issue this statement because the claimed consensus on GMO safety does not exist.”

[11] Antoniou, M, et al.  2012.  GMO Myths and Truths: An evidence-based examination of the claims made for the safety and efficacy of genetically modified crops.  Earth Open Source, page 40.

[12] Antoniou, M, et al.  2012.  GMO Myths and Truths: An evidence-based examination of the claims made for the safety and efficacy of genetically modified crops.  Earth Open Source, page 42.

[13] Dona A, and Arvanitoyannis IS. 2009.  Health risks of genetically modified foods. Crit Rev Food Sci Nutr. 49(2): 164–175.

[14] Antoniou, M, et al.  2012.  GMO Myths and Truths: An evidence-based examination of the claims made for the safety and efficacy of genetically modified crops.  Earth Open Source, page 42.

[15] Pollack A. 2009.  Crop scientists say biotechnology seed companies are thwarting research. New York Times. 20 February 2009. http://www.nytimes.com/2009/02/20/business/20crop.html

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