It was in 1996 that genetically modified (GMO) crops were first grown commercially, yet the debate still rages over their safety and toxicology as well as over their environmental and agronomic impact. And it doesn’t seem to matter whether you’re a supporter or an opponent, you’ve got a stack of scientific studies you can point to as proof of your position.
In fact, the existence of so many opposing studies means this debate is likely to continue far into the foreseeable future.
Besides, as we are learning, no matter how many new studies are done or how many old studies are re-evaluated, there will always be those who keep referencing old and even discounted work to justify their stance.
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Nor should that surprise us. After all, how many people still believe vaccinations can cause autism because of a 1998 report in the medical journal The Lancet that linked vaccinations and autism, despite the fact there were only 12 children assessed in the study, the study was found to be flawed, and the doctor responsible for the study was accused of falsifying data and eventually lost his licence to practise medicine in Britain.
Or consider that some people still believe the earth is flat, or that the earth is only a few thousand years old, or that evolution is a myth, despite all the scientific knowledge gained in the centuries since these ideas were common place and supported by the scientific community of the era.
The best we can hope for in the GMO debate is a strong consensus of scientific opinion, based on evaluation of the many studies into the risks and benefits of GMOs. We need to consider the combined results of all scientific studies of GMOs, pro and con, rather than supporting or rejecting GMO technology based on any single study.
A team of four researchers including Elisa Pellegrino, Stefano Bedini, Marco Nuti, and Laura Ercoli of the University of Pisa in Italy have just completed a review of all peer-reviewed literature of genetically engineered (GE) maize (corn) published between 1996 and 2016.
They reviewed 6,006 publications and compiled the results of all the studies that addressed the agronomic, environmental, and toxicological traits of GE maize. Specifically, their meta-analysis sought to reveal the impact genetic engineering has had on yields and quality of maize, on non-target organisms, on decomposition of biomass in the fields, and on crop protection chemical usage.
Their findings were published on February 15, 2018, in the online journal www.nature.com under the title “Impact of genetically engineered maize on agronomic, environmental and toxicological traits: a meta-analysis of 21 years of field data.”
This is an important review given that about one-third of the corn grown in the world now is planted to GMO varieties. In 2015 there were 53.6 million hectares of GMO corn grown globally, with 33 million ha of that in the U.S. and another 17.4 million ha planted in Brazil, Argentina, and Canada.
Yet 38 countries in the world, 19 of them in Europe, prohibit cultivation of GMO corn. So who is right, the farmers growing GMO corn or the politicians and consumers in countries which prohibit GMO cropping? What are the agronomic benefits and risks of growing GMO corn?
The Pisa meta-analysis addressed five questions. including the effect GE has had on yields. The researchers found: “our study indicated that GE maize hybrids increased yields by 10.1 per cent.” The study found a wide range of yield increase, from 5.6 to 24.5 per cent depending on the hybrid and its GMO traits.
Stacked hybrids which offer both weed and insect resistance provided the highest yield increases. This should not be surprising considering it is estimated insects are responsible for a 31.2 per cent yield loss and that weeds cut yields by 10.5 per cent in corn globally.
Second, the study found GMO actually improved the quality of grain corn. Mycotoxins were 29 per cent lower, fumonisin 31 per cent lower, and thricotecens 37 per cent lower.
GMO corn had 59.6 per cent fewer damaged ears from insect attacks, which is likely the reason for the decreased infection levels. Since mycotoxins are toxic and carcinogenic, the study concluded: “The lower mycotoxin content in (GMO) maize grain can help to minimize the exposure of humans to health hazardous toxins through the diet.”
Third, on the question of the use of crop protection chemicals, the study found the adoption of GMO herbicide-tolerant crops resulted mainly in a shift in which herbicides are used, while GMO insect-resistant technology has effectively reduced the number of insecticide applications.
The authors noted this finding was similar to previous work by other authors which found GMO in corn reduced herbicide usage by 10.1 per cent and insecticides by 45.2 per cent.
Fourth, the study found genetic engineering for insect resistance to be very effective. The study focused on the control of the western corn rootworm and found there was an 89.7 per cent improvement in control of this pest compared to non-GMO corn.
Importantly, the study found GMO had no significant affect on the majority of the non-target organisms’ families.
Finally, the meta-analysis looked at the impact of GMO technology on biomass decomposition. This is important since the decomposition of plant residue affects soil quality and plant nutrition. The study found no change between GE maize and their isolines.
Limitations of the analysis
It is important to note this study only looked at GMO corn. It did not provide any analysis of other major GMO crops, such as soybeans, canola, and cotton.
Second, the analysis concentrated on the agronomics of GMO corn. It was primarily a look at the benefits and risks this technology offers farmers.
Many anti-GMO advocates have claimed this technology has been forced on farmers by industry. However, this study provides scientific evidence of the benefits this technology offers farmers. These benefits are more likely the reason farmers have adopted GMO, and why 12 per cent of global cropland is now planted to GMO crops.
This is the first meta-analysis that evaluates GMO from an agronomic viewpoint.
In their conclusion, the authors stated that 21 years of field data analysis revealed GMO corn offers farmers increased grain yields, improved grain quality, and a decrease in insect damage. They also note modest or no effect on numbers of non-target insects. They found growing GMO corn reduces dangerous mycotoxin levels in grains.
In short, planting GMO corn can lead to increases in income to the farmers and a reduction of health risks to consumers of maize.
As I mentioned earlier, there will always be differing viewpoints and even opposing scientific studies. But by looking at all peer reviewed studies together, you get a balanced consensus on the benefits and risks. In this analysis of thousands of GMO corn studies, the scientific consensus is clear. Genetic engineering provides agronomic, environmental, and toxicological benefits to the farmer, (and indirectly to the consumer through an increased supply of higher-quality, safer corn).
This is a message that GMO corn growers need to share with consumers. The scientific consensus is clear. GMO corn is technology that we are wise to use.
