The world’s population is growing and more people need food. But indiscriminate expansion of land and agricultural practices is undesirable. Cutting down forests to plant other crops will only push an already fragile ecosystem over the edge. Spraying fields with pesticides is also toxic and pollutes the soil and groundwater.
Genetically modified (GM) crops offer a way out. In the 1990s, researchers discovered a way to modify the genome of plants and make specific changes that prevent insects from eating them. In Bt cotton grown in India and Bt brinjal in Bangladesh, scientists added genes from bacteria. Bacillus thuringiensis plant genome, making toxins that kill some insects.
Weeds threaten farms but spraying herbicides to kill them may also kill the plants. There are now herbicide-resistant (HT) GM crops that are resistant to some herbicides, which help farmers kill only weeds. Researchers can also modify crops to have higher yields and/or more nutrients, reducing the need to plant other crops.
GM cultivation tricks
The advent of GM crops has helped farmers practice sustainable methods while increasing food production. But depending on the type of GM crop grown, there are still broader long-term effects. Frederik Noack, an economist at the University of British Columbia (UBC), Canada, and others researched the scientific literature on how GM farming could affect human health and the environment.
The review, published in science in August, he said that there are adverse health effects from many GM crops, while farming methods have complex effects.
“What’s complicated about GM is that you’re not just adding a new genetic organism, you’re adding all the management changes that are there,” said Risa Sargent, an ecologist at UBC and one of the authors of the review. . “The evidence is that management changes are the risk, not the genetics of the organism per se.”
The use of insecticide-resistant crops, such as those with Bt toxins, has shown a low level of risk and has resulted in farmers spraying less insecticide.
“For me, this trait is one of the more positive stories about GM,” said Devang Mehta, a plant biologist at KU Leuven in Belgium. “If you look at India… you see a reduction in the use of insecticides. Farmers are getting less poisoned by these insecticides because they are no longer using them. This is important because Indian farmers often lack special protective equipment.
Profit versus the environment
In some cases, however, pests can develop resistance to Bt toxins over time, leading to increased use of pesticides. This can be solved by planting different types of Bt plants, including areas where non-Bt plants are planted, or by adding other genes to increase the plant’s resistance to pests.
“If we put in just one resistance gene, you put a lot of pressure on the pathogen to overcome that gene, but if you put a stack of resistance genes, it’s harder for the pathogen to overcome it,” Brande said. Wulff, plant and food scientist at King Abdullah University of Science and Technology (KAUST), Saudi Arabia.
But the effect is more nuanced with HT crops. Most are made to resist broad-spectrum herbicides. Farmers benefit because they don’t need to spend more energy and money to remove weeds mechanically: they can just use herbicides and don’t have to worry about their crops dying.
It also reduces the soil, where farmers turn the soil to kill some weeds before planting crops. Cultivation can release carbon that is trapped in the soil, so agriculture does not reduce carbon emissions to some extent.
But only a few large companies grow most of these HT crops in the US, so farmers don’t know much about the herbicides they use.
“GM can be anything it wants to be. But what it does depends on who develops it,” Noack said. “The benefit of (HT plants) for the company is that they also sell herbicides. You can only use that specific herbicide. The most famous company today is glyphosate.
There is no immediate answer as to whether these for-profit companies always have the environment in mind when developing and selling HT crop seeds and accompanying herbicides.
For every solution, a problem
According to the review, farmers using HT crops have not mitigated the use of herbicides; in some cases it has even led to an increase, especially from glyphosate.
“At first, people thought glyphosate would be less toxic because it breaks down so quickly once it gets into the environment,” Noack said. “Now, the latest research shows that it is really harmful to human health.”
Much of the increased use is also driven by weeds rapidly developing resistance to herbicides. The more farmers are encouraged to use special herbicides, including glyphosate, the more weeds will become resistant.
“It’s a bit like antibiotic resistance in medicine, isn’t it? If you keep using the same antibiotics, you have a big problem because the bacteria become resistant,” Mehta said. “… if you use the same herbicide over and over again in the field, you build the problem slowly.”
To combat weed resistance to glyphosate, some GM crops have additional modifications that also complement dicamba, a broad-spectrum herbicide. However, dicamba is potentially more toxic to humans and can spread.
“If you’re a farmer neighbor who uses that herbicide, and you don’t grow GM crops, it just kills all your crops,” Noack said. “The general problem is that every time we create a new pesticide, we create problems downstream.”
Somewhere in the middle
Scientists determine the toxicity of pesticides by testing their short-term effects on mice, although they do not show any such effects. “That’s definitely a very different question than looking at what the long-term impact is on the health of the baby,” Noack added. “If it causes cancer, we won’t see it in the mouse population because the mice won’t live long enough to show it.”
“The industry wants immediate release. They’ve developed some new technology. They want to be able to sell it, which makes sense. It’s a capitalistic driver,” Sargent said. “But we can’t just give people pesticides and see what happens. It often takes years of very careful science to tease out the effects.
Noack believes another reason resistance is developing and spreading is that farmers are all growing the same crops and using the same herbicides. Crop rotation – where farmers plant different crops in the same area – can help reduce dependence on agro-chemicals and reduce resistance.
Sargent recommends using evidence-based preventative measures in pest management, which is not using excessive amounts of herbicide to kill every weed in the field. “Let’s say a complete ban on pesticides is an extreme, and maybe the current agricultural system in many places is the other extreme. Somewhere in the middle there is an approach such as … or integrated pest management,” he said.
“The protocol is that there is an acceptable weed level in the field that will be determined between … specialists and farmers working together.”
‘A very black and white way’
A few companies that manufacture and sell HT plants have monopolized production. It is very expensive to regulate GM crops (more than $40 million for one GM trait to be regulated and eventually commercialized), leaving most government institutions and small companies behind.
Modern tools like CRISPR help scientists make targeted changes to plant genomes, reducing development costs. People are also more accepting of GM when the plant does not contain foreign genes. But the cost of regulation and making sure nothing dangerous enters the market is still too high for institutions that don’t just make a profit.
“I think the problem is that a lot of regulations, including in India, are based on ‘is it GM or not GM’. It’s not a matter of herbicides, insecticides or nutrients,” Mehta said. which is very black and white.”
The review also found more data needed to assess the true impact of GM on biodiversity. In some places, the number of pollinators has decreased, but it is unclear whether this is due to GM crops or urbanization, climate change, and/or other causes of habitat loss.
“We have very little longitudinal data on species trends for almost any species. For most insects, most amphibians, most mammals, how can you go back and say, ‘this is a clear effect on biodiversity’ when we have almost no data?” he asked. Sergeant.
Another confounding factor is that much of the research on GM and biodiversity is sponsored by industry, according to Sargent, which is muddying the waters.
Mark Tester, a botanist at KAUST, said many of the potential environmental effects attributed to GM crops are not unique to GM: they are just natural consequences of agriculture. “You can think of it as a war between agriculture and nature, where we’re trying to feed eight billion people,” he said. “We use the same amount of land used to feed six billion, which means we need to increase production efficiency by 30%.
“It’s definitely tough.”
Rohini Subrahmanyam is a freelance journalist in Bengaluru.
Published – 21 November 2024 05:30 IST
