Do you know which foods are genetically modified?
A recent survey of Americans found that knowledge and awareness of genetically modified foods are low. And more than half mistakenly identify non-genetically engineered (GE) foods. (1)
This confusion regarding GE foods is at least partially a result of there being no requirement to label foods containing GMOs in the United States and Canada.
The below picture contains five foods, four of which could be genetically engineered. Do you know which are which?
This article will focus on answering three questions: What is a GMO? What foods and food ingredients are currently genetically engineered? What are the benefits and concerns with growing genetically engineered crops?
GMO stands for genetically modified organism. Simply put, this means that the genes of an organism (plant or animal) have been genetically engineered (GE) to give the organism a desired trait.(2)
In the United States, GE crops were commercially introduced in 1996, and their adoption for certain crops has been rapid with almost half of the land in the US devoted to farming is used to grow GE crops.(3)
Most Common Genetically Engineered Food Crops
Below is a table of the three most common genetically engineered food crops grown in North America.(3-5)
Also included in the table are the percentages of global acreage devoted to growing these GE crops.(6)
Europe has been included for reference, though only small quantities of insect resistant corn are grown in a few European countries.(7-9)
The low adoption of GE crops in Europe is likely due to two reasons: the EU’s practice of proactively regulating uncertain risks (called the precautionary principle) and the EU’s requirement to label any foods that contain genetically engineered ingredients.(10,11)
With the exception of corn, the GE crops listed above are engineered to be resistant to herbicide.
Genetically engineered corn, along with GE cotton, are also typically engineered to be insect tolerant.
The chart below is a breakdown of the relative proportions of different types of GE traits in corn.(3)
Types of Genetic Engineering
There are multiple types of genetic modifications in crops currently approved for growing commercially.
However, only two GE traits, herbicide tolerance and insect resistance, have found wide-spread global adoption with approximately 420 million acres of these GE crops planted in 28 countries in 2012.(3)
When two or more traits are combined in a GE crop, they are referred to as “stacked.”
A common example of stacked traits are combining herbicide tolerance with insect tolerance in GE corn. Types of GE traits currently grown commercially or approved for commercial use are listed below.
Current Genetically Engineered Crops Grown in North America
The United States is the largest grower of genetically engineered crops, with approximately 50% of its farmland (73 million hectares) devoted to GE crops.(3,6)
Canada is the fifth largest grower of GE crops with approximately 17% of its farmland (11.6 million hectares) devoted to GE crops.(4,6,19)
Below is a comprehensive list of GE crops currently grown in the United States and Canada. The table includes the percentage GE crops contribute to the overall crop harvest, GE trait type, and typical foods and food products containing the GE crops.(3-7,20)
Genetically Engineered Potatoes
In 2016, a new GE potato (White Russet™ potato), was introduced in the United States.
The White Russet™ potato has been genetically engineered to be less prone to bruising and contain less of the amino acid asparagine, which can be converted to acrylamide (a probable human carcinogen) when the potatoes are cooked at high temperatures.(15,21)
A similar GE technique was used to develop the Arctic® line of apples, which are advertised as non-browning apples and are currently being test marketed in the US.(16)
Foods that are NOT Genetically Engineered
Currently, there are no commercialized GE varieties of wheat, rice, barley, or oats.(4,6)
It should be noted however, that though not GE, there are herbicide tolerant rice and wheat crops grown in North America that were developed using traditional plant breeding techniques (more on this soon).(22)
Additionally, there are some GE crops that were only on the market for a short period of time. A GE potato with resistance to the Colorado potato beetle was commercially introduced in the US in 1996, but later withdrawn from the market.(3)
The FlavrSavr tomato, which was genetically engineered to remain on the vine longer and ripen to full flavor after harvest, was pulled from the market due to harvesting and marketing challenges.(3)
Future Pipeline of Genetically Engineered Crops
Innovations in crop science enabling future GE crops are too numerous to list here.
However, a comprehensive database is maintained by the International Service for the Acquisition of Agri-biotech Applications (ISAAA). This database is a good resource for understanding what GE traits are under development and approved for use globally.(23)
Safety of Genetically Engineered Crops
The FDA states that “credible evidence has demonstrated that foods from the GE plant varieties marketed to date are as safe as comparable, non-GE foods.”(24)
When a new GE crop is being assessed by the FDA, they consider questions like “does food from the GE plant contain a new toxin or allergen?” and “is food from the GE plant as nutritious as that from its traditionally bred counterpart?”(25)
When a new GE crop incorporates its own “protectant” or pesticide, as is the case with insect resistant (Bt) crops, the EPA is also involved in the evaluation.(26)
In 2001, the EPA reassessed the safety of crops genetically engineered to contain Bt and determined that “Bt corn and Bt cotton do not pose unreasonable risks to human health or the environment.“(14)
The EPAs assessment consisted of an in vitro digestion assay (to show that the proteins were degraded almost immediately upon contact with stomach acid), in vitro tests to determine if the protein may behave similarly to known allergens, and a high dose toxicity study in animals.(14)
So what does this all mean? GE crops are nutritionally similar to non-GE crops (i.e. similar levels of vitamins, minerals and other nutrients) and the process of genetic engineering does not appear to introduce new allergens into the crop.
Therefore the FDA considers GE crops to be as safe as any other crop that is grown using traditional breeding practices.(26)
When polled, 88% of scientists who belong to the American Association for the Advancement of Science believe GE crops are generally safe.(27)
However, none of these safety assessments take into account the prolific herbicide use on Ht GE crops. Glyphosate (Roundup®) use has grown significantly since the introduction of Roundup Ready® crops in 1996 and is the most commonly used chemical in agriculture.
In 2007 (the most recent date data are available from), 180 million pounds of glyphosate were used in the US alone.(28)
Though the EPA sets tolerances (maximum levels) for all pesticides used in agriculture, there is no routine testing of glyphosate residues in on the crops that we eat or that are included in animal feed.
So we do not have an idea of what our routine day-to-day exposure is to these herbicides. The USDA has tested the glyphosate residue on soy once as a “special project” in their Pesticide Data Program in 2011 and found that 90% of soy beans contained glyphosate residue.(29)
It would be reasonable to assume that other herbicide tolerant GE crops also contain residues of the herbicides they are engineered to be resistant to. And the health impacts of chronic, low-level exposure to herbicides, such as glyphosate, have not been evaluated.
Benefits of Genetically Engineered Crops
As with most complicated topics, my opinion of GMO foods is nuanced. I believe blanket vilification and avoidance of GMOs is unwarranted.
There are a lot of potential benefits that GE crops can provide, especially as we start to see next generation GE crops that are drought resistant and enable vitamin fortified staple crops.
Some benefits, both realized and anticipated, from the genetic engineering of crops include:
Bt Crops Improve Yields
The introduction of insect resistant (Bt) GE crops has enabled farmers to increased crop yields by mitigating crop loss from insects and to use less insecticides.(3)
Additionally, because of EPA mandated requirements, evolution of Bt resistant insects has been delayed.
GE Saves Crops from Diseases
The papaya industry in Hawaii has been saved by developing virus resistant GE crops.(3)
Nutrition and Sustainability can be improved from GE
Next generation GE crops focused on agronomic properties and enhanced nutrition are likely to improve overall availability of food worldwide.
Crops genetically engineered for better drought tolerance are expected to have a major impact on more sustainable cropping systems worldwide, particularly in developing countries where drought will likely be more prevalent and severe.(7)
Concerns with Genetically Engineered Crops
My concern with genetically engineered crops focuses on one type of GE trait: herbicide resistance.
Specific concerns with herbicide tolerant GE crops include:
Herbicide Resistant Weeds are Prevalent and Increasing
As of 2012, there are 14 weed species with documented resistance to glyphosate in the US.(3)
Widespread use of herbicides in GE crop farming has lead to the development of glyphosate resistance in weed species, reducing yields and profits for farmers and increasing use of both glyphosate as other more toxic herbicides.
Next Generation Ht Crops Use More Toxic Herbicides
To combat glyphosate resistant weeds, GE seed producers have recently introduced new GE crops tolerant to the herbicides dicamba and 2,4-D, both of which are more environmentally persistent than glyphosate.(3)
It is Unclear if Herbicide Resistant Crops Improve Yields
Studies by the USDA evaluating whether growing herbicide tolerant GE crops has improved crop yields have mixed results, not showing a clear benefits to farmers.(3)
Unknown Levels of Glyphosate Residue on Crops
Though the EPA sets tolerances (maximum levels) for all pesticides used in agriculture, there is no routine testing of glyphosate residues in on the plants that we eat or that are included in animal feed, even though it is the most commonly used chemical in agriculture.(28)
We do not know what our routine exposure to glyphosate is, and if it poses a health concern or not.
Final Thoughts on GE Crops
I am not anti-GMO. I believe there is a lot of promise in genetically engineering crops, especially in some of the newer technologies that improve vitamin content in crops and inhibit browning of foods (thus preventing waste).
However, I do believe that we should minimize consumption of foods that contain pesticide residues.
I try to avoid eating foods that likely contain herbicide residues, such as glyphosate, by avoiding products made from genetically engineered corn, soy, and canola.
Since neither the United States nor Canada require labeling of genetically engineered food, this means purchasing non-GMO labeled or organic canola oil, corn and soy-containing products.(30)
- Public Perceptions of Labeling Genetically Modified Foods, William Hallman, Rutgers School of Environmental and Biological Sciences, 2013 (link)
- What We Eat, Marion Nestle, 2006 (link)
- Genetically Engineered Crops in the United States, USDA Economic Research Service, ERS Report No 162, Feb 2014 (link)
- Where in the world are GM crops and Foods? Canadian Biotechnology Action Network, 2015 (link)
- Adoption of Genetically Engineered Alfalfa, Canola and Sugarbeets in the United States, USDA Economic Research Center, EIBN 163, Nov 2016 (link)
- Biotech Crops Annual Updates, International Service for the Acquisition of Agri-biotech Applications Website, 2016 (link)
- James, Clive. 2015. Global Status of Commercialized Biotech/GM Crops: 2014. ISAAA brief No. 49. International Service for the Acquisition of Agri-biotech Applications (ISAAA): Ithaca, NY. (link)
- Widespread Bt maize cultivation pays off in Spain, GMO Compass Website, 2010 (link)
- Total EU Corn Production, World Agricultural Production Report, USDA, 2017 (link)
- Comparing Precaution in the United States and Europe, Journal of Risk Research, 5 (4), 317-349 (2002) (link)
- Genetically Modified Organisms Traceability and Labeling, European Commission Website, (link)
- Agricultural Seeds Website, Monsanto (link)
- LibertyLink® Website, Bayer Crop Science (link)
- Are Bt crops safe? Nature Biotechnology, 2003 (link)
- Innate White RussetTM Potatoes Website (link)
- Arctic® Golden Apples Website (link)
- Sale of Innate® Potato Approved in Canada, March 2016 (link)
- Plenish® Soybean Website (link)
- Total farm area, land tenure and land in crops, by province (Census of Agriculture, 1986 to 2006), Statistics Canada Website (link)
- Non-GMO Project, GMO acreage: Papaya (link)
- Acrylamide in Food and Cancer Risk, National Cancer Institute Website (link)
- Clearfield Production Systems for Weed Control, BASF Website (link)
- Genetic Modification Approval Database, International Service for the Acquisition of Agri-biotech Applications, ISAAA Website (link)
- Consumer Information About Food from Genetically Engineered Plants, FDA Website (link)
- How the FDA Regulates Food from Genetically Engineered Plants, FDA Website (link)
- Consumer Info About Food from Genetically Engineered Plants, FDA Website (link)
- Public and Scientists’ Views on Science and Society, Pew Research Center Website (link)
- EPA Pesticides Industry Sales and Usage 2006 and 2007 Market Estimates, 2011. (link)
- USDA PDP Special Projects, Glyphosate, 2011 (link)
- Health Canada Website, FAQ about Biotechnology and Genetically Engineered Foods (link)