Genetically Modified Organisms (GMOs)—The Pros and Cons

There is evidence that a substantial share of the public is both deeply disturbed by the prospect of genetic modification of living things and distrustful of the scientific consensus that that foods derived from plants containing genetically modified ingredients are safe to eat and generally safe for the environment.  Even before Congress passed and President Obama signed a law in 2016 requiring the nationwide labeling of genetically modified food ingredients, consumers have been seeing see more and more products labeled “GMO-free.” In her New York Times article “Fear Not Fact, Behind GMO Labeling,” Jane Brody noted that. “As happened with the explosion of gluten-free products, food companies are quick to cash in on what they believe consumers want regardless of whether it is scientifically justified.” Under the new law, manufacturers will be allowed to label packages with a symbol rather than words to denote genetically engineered ingredients, or with a “quick response” (Q.R.) code that can be scanned with smartphones to retrieve information.  Considering the current confusion and lack of knowledge about GMOs considerable public education may be necessary to allow understanding of any labeling regime and to facilitate wise decisions about GMOs. The Department of Agriculture already has a voluntary certification program and the new law gives the Department two years to develop a national standard for labeling foods.[1]

Most Americans Do Not Trust GMOs
Surveys make it clear that many Americans are concerned and want transparency about whether the genes of plants providing the foods they eat have been modified by genetic engineering (GE). In a 2014 Pew Research Center survey, only 37 percent of American adults said they believed genetically modified foods were safe to eat.  According to a 2015 Associated Press-GfK poll, two-thirds of Americans support labeling of genetically modified ingredients on food packages, and about 4 in 10 said the presence of such ingredients was very or extremely important in judging whether a food is healthy.

GMO labeling is already required in at least 64 countries, including those of the European Union; Russia; Japan; China; Australia; Brazil; and a number of countries in Africa, including Angola, Malawi, Mozambique, Nigeria Sudan and Zimbabwe, where, as Brody notes “… despite rampant food scarcity and malnutrition, American exports that could save millions of lives have been rejected because the crops contained GMOs.”

Science Finds GMOs Safe
Amy Harmon, writing for the New York Times,[2] has pointed out that the National Academies of Sciences, Engineering and Medicine found “no differences that would implicate a higher risk to human health” from GMO crops and that other regulatory, scientific and health organizations, including the World Health Organization, have also concluded that GMOs are safe to eat.  The National Academies report noted, “There was no evidence that GMOs in North America, where such items have been part of the diet since 1996, had contributed to a higher incidence of cancer, obesity, diabetes, kidney disease, autism, celiac disease or food allergies, in comparison with Western Europe, where GMOs are rarely eaten.”  Unlike conventionally bred seeds, genetically engineered seeds need approval from the Department of Agriculture, a voluntary check from the FDA and may get Environmental Protection Agency review. And the FDA has banned labeling of food derived from genetically engineered plants in ways that implied that it was “safer, more nutritious or otherwise has different attributes” than comparable foods because it was not genetically engineered.  In fact, the labeling and marketing of many products as "Non-GMO" may be misleading because genetically modified versions of the same product do not exist. It is also worth noting that for other foods non-GMO labels mean little. For example, DNA from genetically engineered feed is not passed on to meat or milk.

There is a vocal anti-GMO movement warning against the dangers of “frankenfoods” and a scientific community and major corporations including Syngnta, Bayer and Monsanto promoting the use of GMOs as a commercial opportunity, a boon to farmers and consumers, and essential to feed a hungry planet.  A look at what science can tell us about the actual and potential and harms and benefits of GMOs may help dispel the confusion.

Cross breeding and selection of plants and animals as a way to genetically modify them for desirable characteristics has been going on for millennia, but this is almost always a slow process.  These older breeding methods make genetic modification of plants by repetitive selection for favorable characteristics, or with radiation or chemicals. The resulting plants are technically not considered GMOs for labeling purposes because they do not have chromosomes changed with foreign DNA.  These mutant forms are the basis of new varieties of dozens of crops including fruits (e.g. seedless watermelons), vegetables (e.g. orange carrots from a natural mutation) and most of the high-yield wheat and rice varieties that formed the basis of the green revolution. 

It can also be argued that these conventional breeding techniques have deprived foods such as potatoes, corn, apples and various greens of healthy phytonutrients.  But recently, with the assistance of a new technology called marker-assisted breeding it will be possible to speed the selection of fruits and vegetables with a combination of favorable characteristics that relate to taste, nutrition and shelf life.[3]  Unlike the requirement for marketing GMOs there is no requirement to test traditionally bred or marker-assisted bred foods for safety including freedom from causing of allergic reactions.  And there is no ban proposed for many common foods including peanuts, shellfish, and strawberries despite some people being allergic to them.

Genetic Engineering
Genetic engineering is a different and more recent technology that has only become widespread over the past 30 years.  Bioengineering introduces a single or small group of genes.  By altering an organism’s genetic code through transfer of genetic material from another species or synthetic or modified DNA, it is possible to impart new characteristics in a single generation.  Proponents cite examples of advantageous sought after characteristics include higher yields, tolerance to frost, drought or salt, or resistance to insect infestation, mold, disease or weed killer.

The anti GMO movement voices a variety of social and safety concerns.  They note that introducing genes from different species is unnatural, potentially dangerous and may have long-term unknown and unintended deleterious consequences for the environment.  They are also concerned that to their detriment, native plants may be contaminated with new genetic material and that genetically modified crops would mainly benefit large multinational corporations at the expense of poor farmers and consumers.

It may be important to distinguish between bioengineered characteristics that seem to have little downside compared those with potential problems.  For example tolerance to drought or irrigation with saltier water or even resistance to insect pests that would eliminate the spraying with insecticides would seem to be mostly advantageous.  It may be a different story for plants resistant to weed killers that require the use of large amounts of herbicides, however non-GMO plants also may require herbicides.

 First introduced commercially in the U.S. after 1996, by 2013, bioengineered soybeans made up 93 percent of the acreage of planted soybeans, bioengineered cotton made up 90 percent of the acreage of planted cotton, and bioengineered corn varieties made up 90 percent of the acreage planted corn. In addition, bioengineered sugar beets accounted for 95 percent of the acreage of planted sugar beets in the 2009-2010 crop year.[4]  Almost all soybeans and most corn grown in the United States are bioengineered so farmers can spray them with glyphosate (the main ingredient in Roundup) to kill weeds without harming the crop.  There is a legitimate concern about the environmental impact of the widespread use of glyphosate, “a possible human carcinogen,” that reached 113 million kg annually by 2014.  Public health experts urge more scrutiny of the practice and careful testing of the use of newer herbicides, including agent orange, that are designed to work with glyphosate to combat herbicide resistance.

There are also doubts about the supposed increase in crop yields with GMO plants. An analysis by The New York Times using United Nations data showed that the United States and Canada have gained no discernible advantage in yields — food per acre — when measured against Western Europe, a region with comparably modernized agricultural producers like France and Germany.[5]  Also, a recent National Academy of Sciences report found that “there was little evidence” that the introduction of genetically modified crops in the United States had led to yield gains beyond those made by conventional crops.[6] Since genetically modified crops were introduced in the United States two decades ago for crops like corn, cotton and soybeans, the use of toxins that kill insects and fungi has fallen by a third, but the spraying of herbicides, which are used in much higher volumes, has risen by 21 percent.  By contrast, in France, use of insecticides and fungicides has fallen by a far greater percentage — 65 percent — and herbicide use has decreased as well, by 36 percent.
Another controversial example of bioengineering, although not yet widely accepted for use, is Golden Rice.  It was genetically enhanced to be rich in beta-carotene to help counter the vitamin A deficiency that is common in some developing countries. Lack of vitamin A causes blindness in an estimated quarter-million to a half-million children each year in Asia and Africa and the deficiency so weakens the immune system that an estimated 1-2 million, mostly children, die each year from diseases they would be likely to survive.  Golden rice proponents point out that the inserted genes are not likely to be dangerous, they are also found in squash, carrots and melons.

Many countries ban the cultivation of all genetically modified crops, and an Indian environmentalist, called golden rice a “Trojan horse” whose purpose was to gain public support for all manner of genetically modified crops that would benefit multinational corporations at the expense of poor farmers and consumers. Among other anti-GMO groups, Greenpeace dismisses the benefits of vitamin supplementation through GMO’s and has said it will continue to oppose all uses of biotechnology in agriculture. GMO proponents have accused activists causing deaths by delaying the crop’s approval of Golden Rice. “How many poor people in the world must die before we consider this a ‘crime against humanity’?” asked a letter signed by more than 100 Nobel laureates in 2016, petitioning Greenpeace to change its stance.

National Academies of Sciences, Engineering and Medicine
Perhaps the final say should go to the National Academies of Sciences, Engineering and Medicine that in a 607-page report endeavored to make available to the public, to researchers, and to policy-makers a comprehensive review of the evidence about genetically engineered (GE) crops.  It should be noted that only a few species of crops, genetically engineered for just two traits—insect resistance and herbicide resistance—were in widespread use in 2015.  The conclusions of the Academies report were as follows:[7]

  • That crops with the insect-resistant trait—based on genes from a bacterium (Bacillus thuringiensis, or Bt)—generally decreased yield losses and the use of insecticides on small and large farms in comparison with non-Bt varieties.  However, in locations where resistance-management strategies were not followed, damaging levels of resistance evolved in some target insects.
  • That herbicide-resistant (HR) crops sprayed with the herbicide glyphosate often had small increases in yield in comparison with non-HR counterparts. Farm-level surveys did not find lower plant diversity in fields with HR crops than in those planted with non-GE counterparts. In areas where planting of HR crops led to heavy reliance on glyphosate, some weeds evolved resistance and present a major agronomic problem. Sustainable use of Bt and HR crops will require use of integrated pest-management strategies.

  • That a large number of experimental studies provided reasonable evidence that animals were not harmed by eating food derived from GE crops.  Long-term data on livestock health before and after the introduction of GE crops showed no adverse effects associated with GE crops and epidemiological data on incidence of cancers and other human-health problems over time and found no substantiated evidence that foods from GE crops were less safe than foods from non-GE crops.

  • GE crops have benefited many farmers on all scales, but genetic engineering alone cannot address the wide variety of complex challenges that face farmers, especially smallholders.

  • Molecular biology has advanced substantially since the introduction of GE crops two decades ago. Emerging technologies enable more precise and diverse changes in crop plants. Resistance traits aimed at a broader array of insect pests and diseases in more crops are likely. Research to increase potential yields and nutrient-use efficiencies is under way, but it is too early to predict its success. The committee recommends a strategic public investment in emerging genetic-engineering technologies and other approaches to address food security and other challenges.

With regard to regulation the Academy report recommended: “Emerging technologies have blurred the distinction between genetic engineering and conventional plant breeding to the point where regulatory systems based on process are technically difficult to defend. The committee recommends that new varieties—whether genetically engineered or conventionally bred—be subjected to safety testing if they have novel intended or unintended characteristics with potential hazards.”

Bottom Line
So here is the bottom line: Many people are afraid of GMOs but so far their fears are largely unjustified.  Of course, like any new technology, genetic engineered products should continue to be appropriately evaluated and regulated.  And society must assure that its benefits outweigh any risks.  Remember that conventionally bred crops undergo no government testing.  Just as there is no reason to pay extra for Gluten-free foods, so far there seems to be no reason to select or pay more for GMO-free foods.

Endnotes and Links

[1]Brody JE, "Fear, Not Fact, Behind G.M.O. Labeling." New York Times June 9, 2015.
[2]Harmon A. How Square Watermelons Get Their Shape, and Other G.M.O. Misconceptions. New York Times. Updated August 2, 2016.
[3]Jabar F. Building tastier fruits & veggies-no GMOs required. Scientific American July 2014.
[4]United States Department of Agriculture, Economic Research Service. Adoption of Genetically Engineered Crops in the U.S. Updated July 9, 2015. http://www.ers.usda.gov/data-products/adoption-of-genetically-engineered-crops-in-the-us/recent-trends-in-ge-adoption.aspx
[5]Hakim D. Doubts About the Promised Bounty of Genetically Modified Crops. New York Times October 29, 2016.
[6]National Academies of Sciences, Engineering, and Medicine. 2016. Genetically Engineered Crops: Experiences and Prospects. Washington, DC: The National Academies Press. doi: 10.17226/23395.
[7]National Academies of Sciences, Engineering, and Medicine. 2016. Genetically Engineered Crops: Experiences and Prospects. Washington, DC: The National Academies Press. doi: 10.17226/23395.


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