How do we know when we’ve achieved a consensus?

GMO rejection seen through the lens of climate change denial

by Peggy Olive

Relying on the opinions of experts is something we do because we’re not know-it-alls. Through social media the Suzuki Elders have recently discussed genetically-modified (GM) foods. Are they safe for us? Do they improve crop yields as touted? Are they increasing the use of pesticides and herbicides or reducing their use? Are they affecting our environment or livelihoods? Information on the web is often contradictory or misleading, yet an accurate perception of the extent of scientific consensus is essential for public support for or against GM foods.

Contradictory information confuses us, and sowing doubt can stand in the way of government regulation, a ploy used so effectively by the tobacco industry. But let’s look at the example of the Global Warming Petition Project in which 31,000 scientists rejected the consensus opinion on human-induced global warming. They all signed an on-line petition in 2008 urging the US government to reject all global warming agreements on the grounds that they would hinder the advance of science and technology and damage the health and welfare of mankind.

A closer look at this petition is instructive. The only requirement to be listed in the petition was an undergraduate degree in any kind of science. According to the US Department of Education, over 10 million people earned a science degree between 1971 and 2008. So while 31,000 people signed this petition, that’s actually only 0.3% of Americans with science degrees. And, most importantly, only 0.1% of those 31,000 were climate scientists. So the claim that the Global Warming Petition Project disproves the scientific consensus is a myth that uses the technique of a magnified minority. This involves making the petition seem like a large number, when in reality it represents a tiny percent of the scientific community. This myth also uses fake experts which conveys an impression of expertise – 31,000 scientists – when, in fact, 99.9% of the signatories aren’t climate scientists”.

I recently completed a six-week course called Making Sense of Climate Science Denial 101 offered by EdX, a consortium of universities providing free on-line courses on over 500 topics. I can highly recommend this particular course. The material in the preceding paragraph was taken from the first week in the series which introduced us to the idea that we need to look critically at what has been presented to us as “fact”. Science isn’t based on a show of hands, but on evidence. Evidence is published in peer-reviewed journals by scientists who are experts in their field. When evidence from many different sources points to the same conclusion, and when evidence stands the test of time, consensus develops. It is evidence that is responsible for agreement by 97% of climate scientists that humans are causing current global warming.

As an aid to help us identify science “myths” we were given a chart indicating the many ways in which we might be misled by an argument or a “statement of fact”. John Cook, from the University of Queensland and course organizer, came up with the acronym FLICC which stands for Fake Experts, Logical Fallacies, Impossible Expectations, Cherry-Picking and Conspiracy Theories. As an example, when twenty thousand American physicians were quoted in the 1950s as saying “Luckies are less irritating”, this was a red herring intended to distract us from the real questions about smoking safety.

One recent report on GM crops discussed by the Suzuki Elders was entitled “Hundreds of Scientists Warn: No Consensus On Safety of Genetically Modified Crops.” I was tempted to use the FLICC template article to test the hypothesis: what is the evidence for a lack of consensus among experts on the safety of GM foods?

No Consensus: The European Network of Scientists claims no consensus on this question. This group of 68 members offers an on-line petition that anyone with a Ph.D. can sign agreeing that there is no consensus. They also allow you to fill in your own credentials, and in their publication they report that 300 scientists say there is no consensus. I regard this petition as similar to the petition by 31,000 scientists who claim there is no human-induced global warming, a magnified minority. It doesn’t mean that The European Network is wrong, just that this petition doesn’t prove there is a lack of consensus among experts.

Consensus: Obviously the GM foods industry supports a consensus that GM foods are safe. An argument has been made that safety tests are performed by biotechnology companies responsible for their commercialization and therefore their results are suspect. This could be characterized as a conspiracy theory, but I see this more as a myth of impossible expectations. Companies that develop a GM corn plant, a new drug, a car, etc. are required to test them for safety. It is in their own best interests to develop safe products, and they are the ones with the funds and motivation to perform the work. The more relevant question is whether tests performed by industry are designed to reveal all potential health effects, especially over the long term. This is the mandate of regulatory agencies that approve human consumption of GM foods, and this is probably where our concerns should lie. The World Health Organization has published a comprehensive collection of internationally adopted food standards, guidelines, codes of practice and other recommendations for GM foods. These standards are subject to change as more information comes forward. According to the WHO “GM foods currently available on the international market have passed safety assessments and are not likely to present risks for human health.”

Consensus, maybe? In 2012, the Board of Directors of the American Association for the Advancement of Science released a statement on the safety of GMO foods. “The science is quite clear: crop improvement by the modern molecular techniques of biotechnology is safe.” However, this was only a small group of scientists, mostly non-experts in the field of genetic modification of crops and toxicology testing. It should be viewed critically, perhaps seen as a magnified minority in the chart. In fact, it did not represent the view of all AAAS members since it was later challenged in an open letter by a group of 21 scientists, again, a minority of AAAS scientists. Even the 2015 Pew Research Institute report showing that 88% of AAAS members and scientists (numbers now up to 5750) believe that GM foods are “generally safe” could be seen as opinion.

So what is the best way to find out whether there is, or is not, a scientific consensus? If we follow the approach used to show that 97% of climate scientists believe that humans are responsible for current global warming, we would examine all the published, peer-reviewed literature available on the safety of GM foods. For the global warming consensus studies, scientists were able to examine 11,944 papers published worldwide between 1991 and 2011, reporting that fewer than 3% of the papers rejected human-caused global warming. Similar studies were reported by two other groups, enhancing consensus.

Unfortunately, much of the data we would need for GM food safety assessments are not readily available in peer-reviewed journals, and there is a bias against publishing negative results. Safety questions are applied to each GM food because proving one safe doesn’t mean all are safe, or vice versa. That would be jumping to conclusions. Government regulatory agencies do perform an independent analysis of GM crop safety data supplied by the manufacturer, but it is likely that additional studies focused on long-term effects, allergenicity, and antimicrobial resistance may be required to quell concerns and to develop a broader scientific consensus on the safety of GM foods.

This was also the conclusion of the study published in Environmental Sciences Europe. “The scarcity and contradictory nature of the scientific evidence published to date prevents conclusive claims of safety, or of lack of safety, of GMOs. Claims of consensus on the safety of GMOs are not supported by an objective analysis of the refereed literature.” I find it difficult to detect a logical fallacy in this conclusion, although further tests and more regulations do not necessarily lead to safer products or to conclusive proof of safety.

Hidden within this conclusion is another problem which will be just as difficult to tackle: how do we define food safety? The U.S. Food and Drug Administration website has an interesting disclaimer. The FDA says it takes no position on perceived risk of GM foods. It simply approves those that are considered safe by their standards. The recent post on this blog by Stan Hirst provides some insights into the perceptions of GM food safety.

Will scientists or the public accept “generally safe” and “not likely to present risks” without a better understanding of potential risks? A consensus on GM food safety will likely require a more open discussion of what constitutes acceptable risk. This assumes that adverse effects can be demonstrated on which to base risk estimates, by no means a sure thing. As I learned in Climate Change Denial 101, consensus can take a long time to develop, and as my husband quipped after reading this blog, it’s often easier to question findings than to reach conclusions.