GMOs were first introduced to the market in 1996, and since then have been sold throughout the world. These GM crops have many supposed benefits, including resistance to drought, higher survival rates, higher nutritional value, and resistance to pesticides or herbicides. While these seem to be great benefits, the relative novelty of GM crops has made it difficult to predict the long-term effects that they could have on ecosystems and human health. As a result of this, many groups have called for GMOs to be removed from the market and further investigated, under claims that they aren’t safe for human consumption. These groups include Greenpeace, The European Network of Scientists for Social and Environmental Responsibility, and the Union of Concerned Scientists.
One idea that has been commonly argued by anti-GMO groups is the idea that introducing so-called “stacked” plants, plants that have a large amount of modified or inserted genes, into environments with high herbicide use rates, could lead to a strain of superweeds, that is, weeds with resistance to herbicides. Crops could have inserted genes that code for a variety of different advantages, such as resistance to pests and resistance to herbicides, as seen in some genetically modified corn, or resistance to worms, as seen in GM cotton and bananas (Biosciences for Farming in Africa), and the USDA states that there have been genetically engineered crops with genes that code for herbicide tolerance, insect resistance, product quality (flavor or nutrient), drought resistance, and viral/fungal resistance (USDA). The increased commonality of herbicide-resistance crops has increased the amount of herbicides used and sprayed throughout the US, with an increase of 15.6 million pounds of herbicide from 1996, when genetically modified crops were introduced to the market, to 2004, causing the pesticide use on GM crops to rise about 4.1% in that period (UCSUSA).
This increase in herbicide use, as well as the introduction of genes not naturally found in plants or agricultural, led to fears that a strand of herbicide-resistant weeds will develop with some of the stacked genes from the GM crops, and these fears are well-founded, as the Union of Concerned Scientists states that “weed scientists have warned… reliance on HT crops would trigger changes in weed communities and resistance”. The USDA also states that the overuse of glyphosate, the most widely used herbicide in the US, has “contributed to the evolution of glyphosate resistance in some weed species and a shift in weed composition in fields” (USDA). Nature.com provides further evidence to support ideas of superweeds, by stating that farmers in Georgia have seen the Palmer amaranth, a weed that’s a particular problem in the southeast of the US, where it often outcompetes cotton, and “can quickly take over fields” (Nature.com). Roundup, an herbicide with glyphosate as the active ingredient, is used in collaboration with a genetically modified strain of cotton, which was engineered to be resistant to glyphosate, throughout much of the country. This pairing was highly effective until in 2004 this combination resulted in herbicide-resistant amaranth in one county of Georgia, and by 2011 had spread to 76 different counties, according to Nature.com.
There had been arguments made that state that because GM crops have increased the use of herbicides, by making crops herbicide-resistant, they are contributing to the development of newly resistant weed strains. The increasing commonality of GMO crops and consequently the increase of herbicides may also impact the environment by harming other wildlife. For example, although many claims that glyphosate is more “environmentally benign” (USDA), there is still evidence that Roundup is harmful to mice, causing fatty acid liver disease when added to their diets (Nature.com). This could be an indicator of potential harm to human beings as well because the article also states that glyphosate remnants were “routinely detected in foodstuffs and drinking water” (Nature.com), which could prove to be hazardous to people as well.
GMOs may prove to remain controversial for many decades but have already been seen to spread throughout the world, amid great calls for removal from many parties. The long term risks that GMOs pose to human health and the environment may remain to be unseen for generations to come, but proceeding on the basis of the precautionary principle, the idea that to preserve the environment, we need to take action on potential threats before there is scientific data to suggest that the threat could cause damage, would be the least risky, most reasonable way to ensure our safety and preserve the environment.
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