Genetically modified (GM) crops are promoted on the basis of far-reaching claims from the industry and its supporters, such as:
- Humans have been genetically modifying crops for centuries and genetic engineering is no different
- GM crops are safe for human and animal health and the environment
- GM crops increase yields and reduce pesticide use
- GM will produce supercrops that tolerate drought, resist pests and disease, and provide improved nutritional value
- GM crops are “an important tool in the toolbox” to feed the world.
However, based on the evidence presented in this report, these claims are misleading. The GM process is completely different from natural breeding and entails different risks. The GM transgene insertion and associated tissue culture processes are imprecise and highly mutagenic, causing unpredictable changes in the DNA, proteins, and biochemical composition of the resulting GM crop that can lead to unexpected toxic or allergenic effects and nutritional disturbances.
There is no scientific consensus that GM crops are safe, especially when the views of the scientific community independent of the GM crop development industry are taken into account. Toxicological studies in laboratory animals and livestock have revealed unexpected harmful effects from a diet containing GM crops, including some that are already in the human food and feed supply. Among the most marked effects are disturbances in liver and kidney function.
Many of these studies, including some conducted by the GM crop industry and others commissioned by the EU, have been incorrectly claimed by GM proponents to show that GM crops are safe when in fact, they show harmful effects. In some cases, advocates of GM crops have admitted that statistically significant differences were found between the GM and non-GM feeds under test but have dismissed them as “not biologically relevant/significant”. However, these terms have not been defined and are scientifically meaningless.
Most animal feeding studies on GM crops have been relatively short – 30–90 days in length (technically called medium-term studies). What is needed are long-term and multi-generational studies to see if the worrying signs of toxicity observed in medium-term investigations develop into serious disease. Long-term studies of this type are not required for GM crops by government regulators anywhere in the world.
This and other inadequacies of the regulatory regime for GM crops and foods mean that it is too weak to protect consumers from the potential hazards posed by the technology. Regulation is weakest in the US and is inadequate in most regions of the world, including Europe.
GM crops have not delivered on their promises and, based on current evidence, it seems unlikely that they will provide sustainable solutions to the problems that face humanity, such as hunger and climate change.
Claims that GM technology will help feed the world are not credible in the light of the fact that GM technology has not increased the intrinsic yield of crops. While yields for major crops have increased in recent decades, this has been as a result of conventional breeding successes, not due to GM.
Also, the majority of GM crops are commodity crops grown on a large scale for affluent countries, such as soy and maize. A few GM crops have been developed for small-scale farmers in Africa, such as a sweet potato and cassava varieties that were intended to be virus-resistant, but these have failed miserably. In contrast, projects using conventional breeding have succeeded at a fraction of the cost of the GM projects.
GM crops have not decreased pesticide use, but have increased it. In particular, the widespread adoption of GM Roundup Ready crops has led to over-reliance on Roundup herbicide, leading to the spread of resistant weeds. This in turn has required farmers to spray more Roundup and mixtures of chemicals in an attempt to control weeds.
Roundup is not safe or benign. It has been found to cause malformations in laboratory animals, to be toxic to human cells at very low doses, and to cause DNA damage in humans and animals. Epidemiological studies have found an association between Roundup exposure and cancer, premature births and miscarriages, and impaired neurological development in humans. In addition, Roundup applications can cause increases in plant diseases, including infection with Fusarium, a fungus that negatively impacts yields as well as producing toxins that can enter the food chain and affect the health of humans and livestock.
As Roundup fails under the onslaught of resistant weeds, the GM industry is developing multi-herbicide-tolerant crops that withstand being sprayed with potentially even more toxic herbicides, such as 2,4-D. These crops will lead to an immediate escalation in the use of these herbicides.
It is often claimed that GM Bt insecticidal crops reduce the need for chemical insecticide sprays. But these reductions, when they occur, are often temporary. Resistance has developed among target pests and even when control of the target pest has been successful, secondary pests have moved into the ecological niche. These developments demonstrate that GM Bt technology is not sustainable. In addition, Bt crops are themselves insecticide-containing plants, so even when they work as intended, they do not eliminate or reduce insecticides but simply change the way in which insecticides are used.
Advocates often claim that GM Bt crops are safe because Bt toxin has been safely used for decades as a spray to kill pests by chemical and organic farmers. But the Bt toxin expressed in GM plants is structurally very different from natural Bt used as a spray. The Bt toxin in GM plants is not always fully broken down in digestion and has been found to have toxic effects on laboratory animals and non-target organisms fed on such crops.
GM proponents have long promised climate-ready and drought-tolerant crops, but conventional breeding has been far more successful than GM technology in producing such crops. This is unsurprising, as these traits are genetically complex and cannot be produced by manipulating one or two genes.
GM herbicide-tolerant crops are often claimed to be climate-friendly because they are grown using the no-till farming method, which uses herbicides instead of ploughing to control weeds. No-till farming with GM crops is said to store carbon more effectively in the soil than ploughing, which releases carbon into the atmosphere as carbon dioxide. However, studies show that no-till fields do not store carbon more effectively than ploughed fields when deeper levels of soil are measured, throwing into question claims that no-till with GM crops offers a solution to climate change. In addition, the adoption of no-till with GM herbicide-tolerant crops has been found to increase the negative environmental impact of soy cultivation, because of the herbicides used.
Based on the evidence presented in this report, it is clear that GM technology has failed to deliver on its promises. GM technology is fundamentally unsound and poses scientifically proven risks to human and animal health, as well as the environment. The claims made for the benefits of GM crops are highly exaggerated and GM crop technology has been shown to be unsustainable.
It is not necessary to accept the risks posed by GM crops when conventional breeding – sometimes assisted by safe biotechnologies such as marker assisted selection – continues to successfully produce crops that are high-yielding, drought-tolerant, climate-ready, pest- and disease-resistant, and nutritious. Conventional breeding, the existing crop varieties developed by farmers worldwide, and agroecological farming methods, are proven effective methods of meeting our current and future food needs.