The topic of genetically modified organisms (GMO) has been a contentious one for almost two decades. In many parts of the world, fears abound over potential health problems and the prospect of environmental catastrophe, all stemming from the production and consumption of GM foods. While the paranoia is gradually decreasing, lots of misinformation is still thrown about regarding genetic engineering and GM foods. What exactly are GM foods and what are the risks and benefits they confer to both the individual consumer and to the ecosystems in which they are grown?
The first major intersection of genetic engineering and foodstuffs occurred in 1987 with the first tests of a modified version of the bacteria Pseudomonas syringae on strawberry fields in California. The bacteria, which commonly lives on the surface of crops, normally produces a protein that allows ice to more easily begin crystallizing, causing damage to the host plant. However, the strain of P. syringae used in the experiment had been engineered without the gene needed to produce the protein in hopes of reducing frost-induced crop loss. Though the data looked positive following the trial, they couldn’t be fully trusted due to environmental activists destroying some of the test crops in protest of the experiment.
The first genetically engineered food product hit the shelves in the early 1990s in the form of the “Flavr Savr” tomato. Calgene, a Californian company later acquired by biotech giant Monsanto, had engineered the plant to have a slower softening process, though its other ripening attributes like sweetness would develop normally. Tomatoes are often harvested while still green and hard in order to better survive the rigors of transport. Soft, ripe fruit often get smashed or otherwise degraded as trucks bump along rough roads. The Flavr Savr was designed to be both tasty and durable. Unfortunately, due to competition from conventionally bred cultivars (plant varieties), problems with production rates, and troublesome harvesting technology, the Flavr Savr never made a big move on the tomato market. However, it did pave the way for future growth in the GM food market.
Today, there are many genetically modified food crops available, including soybeans, corn, cotton, alfalfa, sugar cane and beets, rice, squash, and others. Their engineering bestows benefits including herbicide, pest, and virus resistance, as well as higher nutritional content by way of increased endogenous production of vitamins and essential fatty acids. In fact, a large majority of soybeans, cotton, and corn grown in the US is now genetically modified organisms, most engineered for herbicide and/or pest resistance. Believe it or not, if you live in the US and many other parts of the world, you almost certainly consume GM foods on a regular basis.
Despite the widespread and longstanding consumption of GM foods by millions if not billions of people, controversy persists over the safety of GM foods in regards to both human health and environmental integrity. While most concerns over GM crops are generally unfounded, it is worth taking the time to understand how GM foods are assessed and approved.
To assess any potential dangers a GM food may present to human health, the product is first analyzed by the manufacturer to determine if it is “substantially equivalent” to its corresponding natural version, if one exists. Substantial equivalence is evaluated by comparing the biochemical profiles of the two foods, including their various carbohydrates, fatty acids, metabolite compounds, and proteins. If the values of the GM food’s components fall within the range of variation of the natural products, then they are deemed to be substantially equivalent. While the standard of substantial equivalence has proven robust enough to prevent any major adverse reactions in the public to GM foods, critics argue that the standard of equivalence is not defined clearly enough nor has a specific procedure for testing been established. In addition, processed or purified products (e.g. oils, sugars, etc.) can be assessed for substantial equivalence independent of their source plants. GMO opponents have claimed that this “loophole” may allow harmful compounds into the human food supply due to the laxity (in their eyes) of the substantial equivalence standard.
If a novel GM product has no natural counterpart, it is evaluated using a seven-part standard safety test. The test begins with an analysis of any new DNA in the product and the proteins or metabolites it may eventually produce. It also includes analysis of the chemical composition of the product, including nutrients, allergens, and toxins. Then, the risk of gene transfer to microorganisms present in the human gut is evaluated. Any new compounds in the product are assessed for possible human allergenicity. Finally, an estimate is calculated to determine how much of the product might be consumed in a normal diet, whether the data indicate any possible nutritional or toxicological risks and, if so, further animal testing is performed to investigate any potentially harmful characteristics of the product.
While opposition groups to GM foods have long claimed that these novel products aren’t tested sufficiently before public release, there has yet to be a documented adverse reaction to any GM food. In addition, these pre-market testing procedures have proven their effectiveness by actually finding allergens in GMO products before release and have allowed the safe removal of the offending foods from the development pathway.
The evidence amassed to date tells us that GM foods pose little to no risk to human health. While there can always be more stringent testing, a balance must be struck between corporate and public interests. If testing is too lengthy or expensive, companies will simply stop developing new products, much like what has happened to the pharmaceutical industry. The current safety testing procedures for GM foods do a fantastic job at both protecting the public and encouraging continued development of needed agricultural technologies.
One of the most commonly cited, real-world instances of “potentially harmful” compounds entering the food supply by way of GM crops was the contamination of corn used to produce Taco Bell hard taco shells with a small amount of a GM variety known as StarLink, which was approved only for use in animal feed. Twenty-eight individuals reported symptoms of allergic reaction resulting from the consumption of the taco shells. It was postulated that “Cry9C,” a protein in the StarLink corn, was the culprit.
Then as now, however, those claims of allergenicity are beset with credibility issues.
First, the US Centers for Disease Control and Prevention performed analyses of the blood of those reporting allergic reactions and found no evidence that the corn had caused their symptoms. Second, allergens are proteins, like the suspected Cry9C protein. The production of a hard taco shell requires frying the corn tortilla in oil at around 365 degrees F. At that temperature, essentially all proteins in the tortilla are denatured, which means that their shape is altered fundamentally, even fragmented. That the tiny amount of Cry9C present in the StarLink material also was denatured at the time of consumption further reduced whatever risk of allergenicity the protein posed in the taco shell. Accordingly, although the recall of the contaminated corn arguably was warranted on regulatory grounds, the fear-mongering and paranoia that followed were unfounded and irrational.
There’s also the argument against GM crops based on potential hazards they might pose to their surrounding ecosystems and the global environment. On the positive side, pest-resistant cultivars have significantly lowered the need for pesticides in many areas. In addition, GM crops also allow for a reduction in farming-related greenhouse gas (GHG) emissions due to more limited use of pesticide spraying equipment and a shift from conventional tillage to reduced/no till practices. Compared to 1996 levels of GHG emissions, GM crops provided global savings of approximately 32.5 billion pounds of carbon dioxide in 2006 alone. That’s the equivalent of taking over 6.5 million cars off of the roads for a year. In addition, GM crops have provided substantial farm-level income increases by way of increased yields, better quality produce, and increased replanting efficiency.
On the negative side, opponents of GM crops have raised concerns about the novel cultivars’ impact on biodiversity, weed resistance, and gene transfer to non-GM crops. On the issue of biodiversity, both sides of the issue agree that it is an important subject to watch. Theories have suggested that, were GM traits passed onto wild relatives, then other native species could be out-competed into extinction. In addition, the release of a particular crop variety with a major advantage over all others could lead to the use of only one cultivar, significantly decreasing crop biodiversity. Yet, while gene transfer between species has been recorded in GM crop locations, no significant negative effects have been noted. As well, seed companies work to prevent the use of a single cultivar by introducing the same trait into many different varieties of a crop. Therefore, the chance of one cultivar becoming overwhelmingly dominant is quite low.
Finally, the issue of weed resistance is worthy of attention and study. Gene transfer from GM crops to wild plants has been shown to occur. However, the occurrence of such an event is extremely rare and the resulting hybrids are often sterile, much like mules and the familiar yellow bananas we find in grocery stores. Despite the low risk of problems with weed resistance, issues have arisen in some areas of the southern US with crop field infestations of herbicide-resistant plants, particularly pigweed. In most cases, the problem was managed by crop and herbicide rotation. In some rare cases, the fields had to be abandoned. Fortunately, the benefits of GM crops grossly outweigh the rare problems they may cause with the development of resistant weeds.
The conclusion here is that GM foods pose little risk to human health. They are studied quite extensively before being put on the market, and the screening procedures have been so successful that no significant health issues related to GM foods have ever been reported. The fact is that GM crops are eaten every day by millions of people in the US alone with no ill effects. On the environmental side, GM crops pose a very small threat to their natural environments. While the concern over gene transfer to non-GM plant species is real, it has never been shown to cause a problem with ecosystem biodiversity. Unfortunately, there is a small risk of resistant traits to undesirable weed plants that can then infest crop fields. However, with diligent farming practices the detriments of such species can be all but avoided in most cases. GM foods offer the farmer and society at large a way to produce healthier, more bountiful produce in a way that is less harmful to the environment. We need higher yields and lower environmental impact to deal with our fast growing human population. Let’s embrace the technologies that we have and get over the irrational fears surrounding GMOs.