‘Robust’ evidence for GM crop benefits, says meta-analysis

By Nathan Gray

- Last updated on GMT

Genetically modified crops have 'significant' benefits in terms of improving crop yield, farmer profits, and reducing pesticide use, according to a new review of 147 trials.
Genetically modified crops have 'significant' benefits in terms of improving crop yield, farmer profits, and reducing pesticide use, according to a new review of 147 trials.

Related tags Genetically modified crops Genetic engineering Genetically modified food

Genetically modified crops offer ‘large and significant’ benefits in both developed and developing countries, according to a new meta-analysis.

The study, published in PLoS One, concludes that despite the wide range of potential applications and potential advantages of genetic modification technologies, on average such crops are of significant agronomic and economic benefit.

The team behind the work analysed data from 147 studies on genetically modified crops, finding that impacts and benefits vary by the type of modified crop trait and geographic region.

“On average, GM technology adoption has reduced chemical pesticide use by 37%, increased crop yields by 22%, and increased farmer profits by 68%,”​ wrote the team, led by Matin Qaim from Georg-August-University of Goettingen in Germany.

Through their analysis, the team showed that yield gains and pesticide reductions are larger for insect-resistant crops than for herbicide-tolerant crops, while yield and profit gains are higher in developing countries than in developed countries.

Confusion and concern

Despite the rapid adoption of genetically modified (GM) crops by farmers in many countries, public controversies about the risks and benefits continue. While numerous independent science academies and regulatory bodies have reviewed the evidence about risks and concluded that commercialised GM crops are safe for human consumption and the environment, many remain wary of genetically modified foods and crops.

Some argue that the evidence about these environmental and agricultural impacts is mixed and that studies showing large benefits may have problems with the data and methods used, while some researchers and organisations firmly believe that genetic modifications can be a risk to human health.

This uncertainty about the impacts and benefits of GM crops is one reason for the widespread public suspicion towards this technology, said Qaim and colelagues.

“We have carried out a meta-analysis that may help to consolidate the evidence,”​ they added.

Benefit analysis 

The team carried analysed the agronomic and economic impacts of GM by collating information from 147 original studies that were built on primary data from farm surveys or field trials anywhere in the world.

“Our meta-analysis concentrates on the most important GM crops, including herbicide-tolerant (HT) soybean, maize, and cotton, as well as insect-resistant (IR) maize and cotton,”​ noted the authors. “For these crops, a sufficiently large number of original impact studies have been published to estimate meaningful average effect sizes.”

From these studies they worked out the average impacts of GM adoption on crop yield, pesticide quantity, pesticide cost, total production cost, and farmer profit.

“Furthermore, we analyse several factors that may influence outcomes, such as geographic location, modified crop trait, and type of data and methods used in the original studies,”​ they reported.

On average, Qaim and colleagues found that GM technology has increased crop yields by 21% - noting that such yield increases are generally not due to higher genetic yield potential, but to more effective pest control and therefore lower crop damage.

“At the same time, GM crops have reduced pesticide quantity by 37% and pesticide cost by 39%,”​ they said. 

However, they noted that this effect on the cost of production is not significant, since GM seeds are more expensive than non-GM seeds. 

“But the additional seed costs are compensated through savings in chemical and mechanical pest control. Average profit gains for GM-adopting farmers are 69%.”

They added that the effects on yield and farmer profit gains were found to be higher in developing countries than in developed countries.

Another twist in the GM debate?

The team suggested that affirming the evidence for the benefits of GM crops “may help to gradually increase public trust in this promising technology.”

There has been a recent backlash towards GM foods and crops in Europe and the USA. European lawmakers recently made it possible for EU member countries to ban the cultivation of genetically modified crops​ on their own soil – even if the wider EU had approved use of the crop.

Meanwhile in the USA, there has been a flurry of anti-GMO activity and several attempts to enforce the labelling of genetically modified ingredients​ on food labels.

Source: PLoS One
Published online ahead of print, doi: 10.1371/journal.pone.0111629
“A Meta-Analysis of the Impacts of Genetically Modified Crops”
Authors: Wilhelm Klümper, Matin Qaim

Related topics Commodities, milling & grains

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