6. GENETICALLY MODIFIED ORGANISMS

Genetically modified organisms (GMOs) have had their genomes directly altered through biotechnology. Genetic manipulation isn’t really a new thing: humans have been using selective breeding to mess around with DNA since the beginning of agriculture. That’s just about 15,000 years. It should be self-evident that things like seedless fruit and dachshunds were not delivered to us by nature. Their unique traits give them no evolutionary advantage. However, humans have found some of those maladaptive traits desirable and have nurtured them into existence. We’re all used to that, and it isn’t the sort of thing we protest unless someone tries to cross a human with a chimpanzee (yes, people have tried that). It’s safe to say that on some level we’re all okay with genetic manipulation (because grape seeds are the worst).

However, modern genetic engineering techniques introduce a couple of new twists. First, they allow us to edit a single gene at a time. Selective breeding selects for suites of genes because most of the observable characteristics of an organism (its phenotype) are controlled by more than one gene. In addition, biotechnology allows for DNA mixing in organisms that could never sexually reproduce (like spiders and goats). This is the part that tends to freak people out—a lot.

Before we get into that, let’s ask why someone would even want to do anything so bizarre. Lots of reasons. For example, most of the insulin sold to diabetics is made by bacteria. Bacteria do not naturally make insulin (they don’t have pancreases), but genetically engineered bacteria can. This is huge, because prior to the invention of biosynthetic human insulin in the early 1980s, insulin had to be animal sourced, commonly from pigs. Taking insulin from a pig’s pancreas kills the pig. So, from the pig’s perspective, genetic engineering provides an alternative that is clearly better.

But the most common application of genetic engineering, and the one that draws the most criticism, is in agricultural crops. Genetic modifications can confer insect and herbicide resistance, higher nutritional content, the ability to withstand drought and freezing, and longer shelf life.

Many different kinds of genetically modified crops have been developed, but Bt corn, soybeans, and cotton are the most widespread. Bt crops have had some genes inserted from the soil bacterium Bacillus thuringiensis into their genomes, which is where the name Bt comes from. As a result of this modification, these plants produce some of the insecticidal compounds that are naturally produced by the bacterium, and the insects that would otherwise eat them are destroyed. Farmers no longer have to spray with insecticide (or at least they need far less of it) because the insecticide is built in. Yes, that means people who eat the genetically modified produce are eating the insecticide, and yes, that does sound scary. But keep in mind that many plants, including food crops, already produce insecticides. The war between plants and insects has been going on for a long time. Insecticidal compounds are not necessarily dangerous to humans, because insects are very different from us. It is also worth bearing in mind that Bt is considered to be one of the safest pesticides in the world. If you eat organic produce to avoid GMOs, you are still exposed to a lot of Bt.

Herbicide resistance is another common attribute of genetically modified crops. The idea is that if the food crop is immune to the herbicide, that herbicide can be used as a weed killer. Most genetically modified crops are resistant to glyphosate, commonly known as Roundup.

Proponents say these modifications increase crop yields, decrease pesticide and herbicide use, and contribute to economic stability for farmers and food security for everyone. Critics claim that GMOs have adverse health consequences (e.g., allergies, cancer, digestive issues) for consumers and negative environmental impacts (e.g., effects on nontarget organisms, extinction of original species, and insect and weed resistance).

The anti-GMO movement is, without exaggeration, huge, and it’s having a significant impact on public perception. According to a survey by the Pew Research Center, 57% of the general public considers GMO foods generally unsafe to eat. This is especially striking because 88% of AAAS scientists think they are generally safe to eat. In case you’re wondering, the AAAS is the American Association for the Advancement of Science, the world’s largest general scientific society and the publisher of the highly regarded journal Science. A 2012 statement from the AAAS board of directors states that GMOs are not inherently more dangerous than the same foods modified by conventional techniques such as selective breeding. This statement points out that this opinion is shared by the European Union, the World Health Organization (WHO), the American Medical Association, the U.S. National Academy of Sciences, and the British Royal Society. That’s a highly credentialed set of sources, and if you believe that science is a fundamentally useful way to know things, then this should ease your mind about GMOs. Genetically modified crops are extensively tested before they are approved for use, and there is no evidence that they are dangerous to the humans or animals that consume them.

But it is difficult to make sweeping generalizations about GMOs because there are many of them, and the number is increasing. In addition, the technologies that are used to create GMOs are changing, and government regulations aren’t always keeping up. To examine some of these issues, in 2016 the National Academy of Sciences (NAS) commissioned an expert panel to prepare an extensive review of GMOs. The committee reviewed the scientific literature, listened to the testimony of many speakers, and read hundreds of public comments. They produced a 600-page report that is freely available online and a four-page brief on the topic.

The NAS committee publicized several key findings. First, they found no conclusive evidence that GMOs harm the environment. In fact, there is evidence of environmental benefits in terms of reduced pesticide use and enhanced insect biodiversity. However, the NAS did couch this statement with the caveat that definitive conclusions are difficult to reach because of the complex nature of the problem. They also noted that while there is good evidence that genetically modified crops do legitimately increase yields, the rate at which these increases have developed is not significantly greater than what is expected through conventional breeding strategies. In terms of health, the committee found no evidence that genetically modified foods pose a greater health risk than their conventional counterparts. Again, however, the committee added the caveat that these effects might be very subtle, or they may take a long time to develop. The 1980s might seem like a long time ago, but it may not be long enough to capture all of the long-term effects. The committee found that the impact on social and economic variables was mixed and context dependent. They did stress that while genetic engineering may have a role to play, it would not, in and of itself, ensure future food security. Finally, the committee recognized that both genetic engineering and conventional breeding can result in negative outcomes. Their recommendation, therefore, was that all new plant varieties with potentially hazardous characteristics be subject to safety testing. This last point about regulation is important, not just because there is little oversight of conventionally bred organisms, but because some of the newer technologies for genetic engineering do not fit into the definitions used by some regulatory agencies.

So the report offers neither a ringing endorsement nor a resounding condemnation for GMOs. All technologies (including fire and the wheel) have the potential for good, bad, and unexpected outcomes.

SUMMARY

Preventability (77)

There are GMO-free versions of many, but by no means all, foods. Of course, even if you go completely GMO free, the environment you live in may still be affected by GMO crops.

Likelihood (13)

The most common GMO crops do not appear to cause health problems, but that doesn’t mean there can’t be any problems down the line.

Consequence (21)

At present, GMO crops are more likely to have environmental impacts than they are to have individual health impacts.

REFERENCES

Funk, C. (2015, January 29). 5 key findings on what Americans and scientists think about science. Pew Research Center. Retrieved from http://www.pewresearch.org/fact-tank/2015/01/29/5-key-findings-science/

National Academies of Sciences, Engineering, and Medicine; Division on Earth and Life Studies; Board on Agriculture and Natural Resources; Committee on Genetically Engineered Crops: Past Experience and Future Prospects. (2016). Genetically engineered crops: Experiences and prospects. Washington, DC: National Academies Press.

Servick, K. (2016, May 17). Once again, U.S. expert panel says genetically engineered crops are safe to eat. Science. Retrieved from http://www.sciencemag.org/news/2016/05/once-again-us-expert-panel-says-genetically-engineered-crops-are-safe-eat