By Anastasia Bodnar and Karl Haro von Mogel
It seems like every news article about genetic engineering gives a nod to unknown risks to the environment or human health that are unique to genetic engineering. What are those risks, and are they really unique?
Before we get into the details of specific potential risks, there are three things we need to consider.
- Is a risk unique to genetic engineering as a whole or risks of individual traits of categories of traits? Each individual trait, whether bred or engineered, must be examined for safety and appropriateness in the situation in which it will be used.
- What is the risk compared to alternatives? Risk associated with a genetically engineered trait may be less than the risk associated with a practice that it will replace.
- What is the source of the risk? Is it something inherent in the trait or are there external factors?
One of the most common concerns is with the process of genetic engineering – the transfer of one or more genes from one species to another and potential for unintended genetic changes during the process. While it is possible that unintended changes can occur, this risk is not unique to genetic engineering. Natural and induced mutagenesis as well as traditional breeding methods can also introduce unintended genetic changes, resulting in additional genes being turned on or off, deletions, duplication, and other changes in the genome. Crossing crop plants with wild relatives can introduce genes and proteins that have never been in the human food supply, as can genes inserted through genetic engineering.
In the United States and Canada, genetically engineered crops are generally used in farms grown with a monoculture system. However, these farms were monocultures before the advent of genetic engineering and would continue to be monocultures if genetic engineering disappeared tomorrow. Monoculture farming is a problem in and of itself, separate from genetic engineering. In India and Africa, genetically engineered crops (specifically Bt cotton and Bt maize) is grown in a variety of systems. Virus resistant papaya is grown in both larger production farms and in people’s backyards.
Whenever a pesticide is used year after year in the same place on the same target populations, resistance to that pesticide will develop. This is not a problem specific to genetic engineering. With any pesticide, and with any genetically engineered crop that involves pests, the pesticides must be rotated to prevent any resistance genes that develop from spreading throughout the population. While crops resistant to glyphosate have resulted in a switch away from other herbicides to glyphosate which has resulted in an increase in glyphosate resistant weeds, this is not due to genetic engineering. The problem is a lack of integrated pest management strategies that incorporate a variety of solutions.
Microorganisms and other non target organisms
Another concern that some people have is about genetically engineered crops is that they might have a negative impact on soil microorganisms, beneficial insects, and other wildlife. It is possible that some genetically engineered traits might impact wildlife. Of course, each trait must be assessed individually and we must determine what is the relative risk compared to other options. For example, it is possible that a particular type of Bt in maize would have an effect on soil microorganisms compared to a similar maize without Bt, but that many pesticides against root worms would be even more disruptive for soil microorganisms.
There is one particular example that we need to address in this section. We’ve all heard the story about Monarch butterflies being harmed by genetically engineered crops. First, it was claimed that Bt in pollen harmed the butterflies. Thankfully, those claims were wildly exaggerated – the result of experiments that did not match real-world conditions. Next, it was claimed that monarchs are harmed because the herbicide glyphosate is being used to kill weeds, including the milkweed that Monarchs need to live. However, this is not a problem of glyphosate resistant crops. It is a symptom of a larger problem – that of sterile lawns without weedy flowers that feed butterflies and of farms that are planted border to border without much wild land between.
Modifying biochemical pathways
Plants have enormously complex networks of biochemical pathways that create almost every substance that the plants need. These pathways, like a network of roads and highways, are interconnected and have only begun to be understood. Some of the kinds of genetically engineered crops that are beginning to emerge involve modifying these pathways to produce more of a desired substance or less of an undesired one. For instance, some work on Cassava focuses on reducing the amount of toxic compounds in the roots, and the well-known Golden Rice Project involves boosting beta-carotene in the grain to combat vitamin deficiency. It is possible that modifying the levels of these and other substances in the plant can have effects on other parts of the system, and modify the plant in some undesirable way.
This kind of risk must also be taken in the context of the history of plant breeding. The crops we eat today are replete with examples where drastic changes in biochemical pathways have occurred through simple breeding with no understanding of the underlying biochemical mechanisms. For instance, carrots were not originally orange but white and purple in color. The accumulation of genetic mutations, and the long process of breeding resulted in a nutritionally modified vegetable that is today one of the richest sources of beta-carotene in our diets today. The biochemical pathway that produces beta-carotene in orange carrots and Golden Rice is the same, and the risks involved in modifying such pathways would therefore be similar.
What if it works?
Modifying the nutritional content of foods through genetic engineering has the potential to reduce suffering and improve human welfare. Modifying a plant to resist insects has the potential to reduce insecticide sprays and improve yields and/or food security. There are countless other risks involved in agriculture and food that are dealt with on a regular basis. So when discussing the risks involved in genetic engineering, it is important to consider the risk that it will succeed in reducing or mitigating these other risks.
When evaluating the risk of doing something, you should also consider the risks involved with not doing something. As with driving a car or having electricity in your home, there are benefits that come along with the risks of genetic engineering – and all of these need to be taken into account together.
These are just a few examples of broad claims of risk that are often attributed to genetic engineering that are much more complex issues when you examine them more closely. Can you think of others? Lets hear them in the comments.