Gmos' Impact: Pollution And Environmental Effects Explained

Genetically modified organisms (GMOs) have been available to consumers since the 1990s. While they have been touted as a potential solution to the global food crisis, their impact on the environment has been hotly debated. GMOs can affect pollution in a number of ways. Firstly, herbicide-tolerant GM crops have been linked to increased herbicide use as weeds develop resistance, leading to the emergence of superweeds. This can result in greater chemical pollution and harm to biodiversity, water, and air. Insect-resistant GM crops, on the other hand, have contributed to a decrease in insecticide use, allowing for a higher diversity of beneficial insects. However, there are concerns that these crops may negatively impact non-target insects and reduce their populations. The proliferation of GM crops can also lead to genetic contamination, threatening the existence of natural plant varieties and organic farming. Overall, the impact of GMOs on pollution is complex and multifaceted, with potential benefits and drawbacks that need to be carefully considered and regulated.

Increased herbicide use

Herbicide-resistant crops are genetically modified to survive the application of certain herbicides, allowing farmers to more easily control weeds in their fields. This technology was widely adopted for commercial use in 1996 and is mainly used in corn, soybean, cotton, and canola crops.

The introduction of herbicide-resistant crops has led to an increase in herbicide use. In the US, herbicide-resistant crop technology led to a 239 million kilogram (527 million pounds) increase in herbicide use between 1996 and 2011. This increase has been driven by two main factors: the emergence and spread of glyphosate-resistant weeds, and the reduction in the application rate of herbicides other than glyphosate.

The emergence of glyphosate-resistant weeds is a significant factor driving up herbicide use. Glyphosate-resistant weeds were practically unknown before the introduction of herbicide-resistant crops in 1996. Since then, the number of glyphosate-resistant weed species has increased rapidly. As of 2021, there were 59 weed species resistant to glyphosate worldwide, with 17 species in the US alone. The heavy reliance on glyphosate has placed weed populations under intense selection pressure, leading to the emergence of resistant weeds.

In addition to the emergence of glyphosate-resistant weeds, there has been a reduction in the application rate of other herbicides. The pesticide industry has made progress in discovering more potent herbicidal active ingredients that are effective at progressively lower rates of application. This has resulted in a decrease in the overall volume of herbicides applied but an increase in the number of applications.

The increase in herbicide use has had several environmental impacts. It has impaired soil microbial communities, reduced the availability of certain soil minerals and micronutrients, and negatively impacted insect and bird species. For example, the expansion of herbicide-resistant corn and soy has destroyed much of the habitat of the monarch butterfly in North America. Additionally, the heavy use of glyphosate can reduce earthworm viability and water use efficiency.

While herbicide-resistant crops have led to an increase in herbicide use, it is important to note that the environmental impact of this technology is complex and depends on various factors. The comparison of herbicides used on herbicide-resistant crops versus conventional crops must consider not only the net amount used but also the environmental impact of the herbicides. The environmental impact quotient (EIQ) is a method used to measure the impact of individual pesticides on the environment. In some cases, the EIQ values of herbicides used on herbicide-resistant crops are better than those used on conventional crops, indicating a potential improvement in environmental impact.

Emergence of superweeds

The emergence of "superweeds" is a consequence of herbicide-tolerant crops, particularly glyphosate-tolerant "Roundup Ready" crops. The widespread and repeated application of glyphosate, a herbicide, has led to the evolution and spread of weeds that are resistant to it. These "superweeds" can no longer be killed by glyphosate, and they infest fields, competing with valuable crops for nutrients. This has resulted in farmers turning to other, often harsher, herbicides to control them.

The use of glyphosate-resistant crops has been linked to the development of superweeds. Since the introduction of these crops, about 38 weed species worldwide have become resistant to glyphosate. This number rises to 59 species when considering all weeds that have developed resistance to herbicides due to the increased use of GM crops.

The emergence of herbicide-resistant weeds is not a new phenomenon. The first instances were observed in the 1950s with the introduction of industrial farming methods and chemical herbicides. However, the introduction of herbicide-tolerant crops has accelerated and entrenched this pattern. Large areas of cropland are repeatedly sprayed with the same herbicide, leading to the evolution of superweeds.

The spread of herbicide-resistant weeds has economic and environmental implications. In the US, weed management costs in infested fields are 50-100% higher per hectare than in fields without glyphosate-resistant weeds. Additionally, the use of harsher herbicides to combat superweeds can have serious impacts on the environment and human health.

To address the problem of superweeds, companies are "stacking" multiple herbicide-tolerant traits into a single seed. For example, Canada approved the first GM corn tolerant to the herbicide 2,4-D in 2012, followed by the approval of GM corn tolerant to dicamba in 2016, and then a GM corn tolerant to both 2,4-D and dicamba in 2020.

Biodiversity loss

The use of GMOs has transformed the agricultural landscape, and while GMOs are not inherently harmful to the environment, certain practices associated with their cultivation can have negative consequences for biodiversity.

One of the primary ways in which GMOs contribute to biodiversity loss is through the overuse of herbicides. Herbicide-tolerant GM crops have led to a significant increase in herbicide use, with sales in Canada rising by 244% between 1994 and 2021. This has resulted in the emergence and spread of "superweeds", or weeds that have developed resistance to specific herbicides. The repeated use of the same herbicide on herbicide-tolerant crops, whether GM or non-GM, contributes to this problem. The loss of plant diversity in agricultural systems can have far-reaching ecological impacts, as it reduces habitat and food sources for important organisms such as pollinators and other beneficial insects.

The cultivation of herbicide-resistant GM crops can also have indirect effects on biodiversity. For example, the expansion of herbicide-tolerant corn and soy in North America has destroyed much of the habitat of the monarch butterfly, leading to a decline of over 90% in its population in less than 20 years. Additionally, toxins from genetically engineered insect-resistant corn have been found to wash into nearby streams, impacting aquatic insects such as caddisflies.

The introduction of GMO crops can also affect biodiversity by outcompeting existing species. If released into the environment, genetically modified animals, plants, and organisms can become dominant and displace other species. This can have complex and unpredictable ecological consequences, as the presence or absence of a single organism can have far-reaching effects on the ecosystem.

While the use of insect-resistant GM crops can reduce the application of environmentally damaging insecticides, there are also potential drawbacks. Insects can develop resistance to the toxins produced by GM insect-resistant crops, leading to the emergence of "superpests". Additionally, these toxins can impact non-target organisms, such as spiders, wasps, ladybugs, and lacewings, which are predators that feed on the targeted insect pests.

Overall, while the use of GMOs in agriculture has the potential to bring benefits, it is important to carefully consider and address the potential risks to biodiversity.

Greenhouse gas emissions

The adoption of genetically modified (GM) crops has been linked to a reduction in greenhouse gas emissions. In a study covering the period 1996-2016, it was found that GM crops contributed to a reduction in fuel use from less frequent herbicide or insecticide applications and a reduction in the energy use in soil cultivation. The study also found that the use of reduced tillage or no-tillage (RT/NT) farming systems, facilitated by herbicide-tolerant GM crops, resulted in permanent savings in carbon dioxide emissions. In 2016, this amounted to a saving of 2,945 million kg of carbon dioxide, arising from reduced fuel use of 1,309 million litres. This is equivalent to taking 1.8 million cars off the road for one year.

The adoption of GM crops has also facilitated a shift from conventional tillage (CT) to RT/NT systems, which has resulted in a reduction in fuel use. The fuel savings from this shift are drawn from a review of literature, including studies by Jasa (2002), Conservation Tillage and Plant Biotechnology (2002), and the University of Illinois (2006). This analysis assumes that the adoption of NT farming systems in soybean production reduces cultivation and seedbed preparation fuel usage by 27.12 litres/ha compared with traditional CT, and in the case of RT cultivation by 10.39 litres/ha. The adoption of NT and RT systems in respect of fuel use therefore results in reductions of carbon dioxide emissions of 72.41 kg/ha and 27.74 kg/ha, respectively, for soybeans, and 65.17 kg/ha and 20.08 kg/ha for maize.

In addition to the direct reduction in fuel use, the use of RT/NT farming systems has been found to increase the amount of organic carbon stored or sequestered in the soil, further reducing carbon dioxide emissions. This is because RT/NT systems reduce soil cultivation and seedbed preparation, leading to enhanced soil quality and reduced levels of soil erosion. As a result, more carbon remains in the soil, contributing to lower greenhouse gas emissions.

The adoption of GM crops has also been linked to increased yields, which allows farmers to grow more food without using more land. This can help to reduce greenhouse gas emissions by preventing the need to convert new lands to agricultural use. A study by the University of Bonn projected that if the European Union (EU) were to adopt existing GM crops, it could reduce greenhouse gas emissions by 33 million tons of CO2 equivalents per year, or 7.5% of the total agricultural greenhouse gas emissions of Europe. This reduction in emissions is due to both the direct effects of GM crops on yield increases and the indirect effects on preventing land-use change.

Overall, the adoption of GM crops has been associated with a reduction in greenhouse gas emissions, primarily through reduced fuel use and increased carbon sequestration in the soil. This contributes to the fight against climate change and helps to secure global food supplies in a more sustainable way.

Genetic contamination

Since the introduction of GM crops in the 1990s, there have been numerous recorded instances of genetic contamination worldwide. One notable example is the contamination of non-GMO crops by GMO crops, which has resulted in the loss of markets, particularly those requiring "GM-free" products. This has had significant economic implications for farmers, who often bear the brunt of GM contamination.

Another concern is the potential introgression of GMO traits into wild and feral populations of crop relatives, which can lead to reduced capacity for co-existence with non-GMO crops and hamper future breeding efforts. The contamination of non-GMO seeds with GMO material can also impact the future supply of non-GMO seeds, especially for seed saved from open-pollinated crops.

Furthermore, genetic contamination can have environmental implications, such as a decrease in plant diversity and the loss of habitat and food sources for other organisms. For instance, the expansion of GMO herbicide-tolerant corn and soy has been linked to the destruction of the monarch butterfly's habitat in North America.

To address these issues, regulatory bodies like the U.S. Food and Drug Administration (FDA), the U.S. Environmental Protection Agency (EPA), and the U.S. Department of Agriculture (USDA) assess the environmental impacts of GMOs before they are approved for commercial use. Additionally, international agreements like the UN Cartagena Protocol on Biosafety aim to control the movement of living GMOs across borders.

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