Global Context of Glyphosate Use and Misuse

  • Daniel Henryk Rasolt – Unbounded World

For many, glyphosate conjures up images of vast industrial monocultures, genetically engineered crops, and huge global industries and corporations. But glyphosate in particular, as the world’s most widely used herbicide, has and continues to have many other applications, and its full impacts on human and environmental health are poorly understood.

No matter on which side of the “GMO debate” one falls, or how toxic or carcinogenic one believes glyphosate itself to be, or how long glyphosate residues actually stay on plants and within different types of soils, any fair assessment shows that there have been grave misuses and overuses of this “organophosphorus ” chemical compound (specifically a “phosphanoglycine”), with insufficient consideration for its potentially far-reaching consequences.

If one believes in the “green revolution,” and further supports a world full of vast genetically modified (GM) soy, corn, cotton, sugarbeet, alfalfa, canola, wheat and other cash-crop monocultures, then glyphosate was and is something of a miracle weed-killer. According to this viewpoint, these crops can feed (and in the case of cotton, cloth) the growing billions around the world, and glyphosate can help make sure no unwanted intruders get in the way.

Of course, for those that appreciate the diversity both of nature, including its trillions of invisible and mostly forgotten microorganisms, and diets that are based around numerous different whole foods, the above vision is particularly appalling.

The technology of genetically engineering foods (what has become known as genetically modified organisms, or “GMOs”) is poorly understood by the public, and distorted on both sides of the debate to generate fears, hopes, and/or sales. The basic science behind the technology of genetic engineering may in fact be an important tool in a world of advancing climate change and prolonged droughts, but it needs to be transparently studied and debated on a case-by-case basis. As with many technologies, it is the way in which GMOs have been developed and implemented that is the main problem, not the basic science.

Such is the case with the synthesis/discovery of glyphosate by Monsanto in 1970, which branded the chemical as “Roundup” for commercial use in 1974. Monsanto subsequently developed and continues to develop “Roundup Ready” crops that are resistant to glyphosate, through the technology of genetic engineering. Soy was the first Roundup Ready crop developed in 1996, followed by corn in 1998. Although Monsanto no longer has exclusive patent rights to the glyphosate formula (it became publicly available in 2000), their patented GM seeds have helped generate a “virtuous cycle” where the seeds grow sales of Roundup, which generates more seed sales. These Roundup Ready crops were intended to thrive under a simplified industrial system, where short-term yield is valued above integrated and sustainable future planning. Glyphosate’s ability to kill a wide range of plants that were not engineered to be resistant to its powers, made it the ideal chemical to spray on these monocultures.

What goes on below the soil and in the ecosystems that border these industrial farms, and also what happens to humans over the long-term when eating these foods and potentially inhaling or consuming the glyphosate residues, is what makes this simplified industrial model so suspect for Roundup Ready crops (not to mention that a growing number of weeds are evolving a resistance to glyphosate). Also the numerous misuses of glyphosate outside of its “appropriate” setting on an industrial monoculture, has caused sweeping harms, and is something that the public and policy makers need to be much more aware of when regulating the sale and use of this chemical compound.

The indiscriminate aerial spraying of glyphosate in Colombia under the umbrella failure of “Plan Colombia” that was aimed at the eradication of coca plantations (coca being the base ingredient of cocaine), is a particularly egregious example of the misuse of glyphosate. Incredibly, despite the failures of Plan Colombia in curtailing cocaine production, and the poorly understood but widespread environmental and social impacts that were wrought by the aerial spraying of glyphosate, as of 2019 the Colombian government, supported by the United States, is re-initiating the “strategy” of aerial fumigation of glyphosate.

“Drifting Droplets” – Vannessa Circe – Oil on Canvas – 2019

Controversy with the use of glyphosate in Colombia

  • Dr. Jairo Leonardo Cuervo Andrade – National University of Colombia, Faculty of Agrarian Science, Bogota, D.C.

A History of Combating Weeds

Agricultural activity has undergone important transformation processes in the last decades, which has meant an increase in the planted area of products for human consumption, fodder and forestry. This, coupled with the use of transgenic crops, has meant an increase in the use of naturally occurring and synthetic herbicides and pesticides, which are essential for controlling pests, diseases and weeds in intensive production processes.

Indeed, weeds are often the main biotic constraint in agricultural production for countries in the developing world, and the growing need to increase agricultural production for rising populations poses an immediate challenge for specialists in weed science.

From the anthropocentric point of view, weeds are considered to be plants that interfere in one way or another with the activities of people; however, biologically these plants are invaluable because they constitute fundamental links within any ecosystem. For wild or native vegetation a weed (arvense) is considered to be a plant that at any given time can interfere either allelopathically or by competition with other plants for water, nutrients, light, CO2, O2 and space. With crops, these weeds economically impact the productive system.

The combat against weeds originated when humans abandoned hunting and gathering practices and developed agriculture, becoming sedentary. Since this time, humans have devoted great efforts to combating weeds: first manually, then later with the employment of some artifacts, tools and equipment to improve efficiency.

As areas of high density weed infestation increase, it is essential to make rational and effective crop management choices to ensure the integrity of the productive system. In this sense, weed control with herbicides can be effective and safe, provided that environmentally safe herbicides are used and appropriate precautions and methods of application are taken.

The management of weeds, especially in extensive crops, is based on the use of herbicides. This is because the herbicides are much more effective and profitable than manual weeding. Using herbicides often yields a return of several times the investment due to their ability to kill weeds without damaging the cultivated plants. However, selectivity is a relative term, since all the herbicides cause damage to the crops if they are applied at higher doses than those recommended for a certain type of soil or the phenological stage of the crop.

Preparing to fumigate potatoes in the Andes. Cauca, Colombia

The production and use of chemical compounds in agriculture for the control of pests, diseases and weeds, has intensified since the Second World War. This has given rise to a growing concern about the potential impacts that these compounds have on terrestrial and aquatic ecosystems. Due to their specific chemical characteristics, some herbicides and pesticides for agricultural use are persistent pollutants that resist to varying degrees the natural cycles of photochemical, chemical and biochemical degradation, so for certain herbicides and pesticides, the average lifespan in the environment can be very high.

Glyphosate: The World’s Most Popular Herbicide

Glyphosate [N- (phosphonomethyl) glycine] is an herbicide highly soluble in water (12 g / L) and insoluble in all organic solvents. It is used in foliar applications for the non-selective control of a wide range of species of adventitious plants, in doses between 0.34 to 4.43 kg ai / ha. Today it is one of the most popular herbicides not only for agriculture but also for forestry, due to its effective control over undesirable spontaneous vegetation and declared low toxicity for mammals. Glyphosate is by far the most used herbicide in the world; additionally, its use has increased in recent years due to the planting of tolerant crops to this herbicide (so-called “Roundup Ready” crops in the United States).

Currently in Colombia glyphosate’s use is controversial, due to its often indiscriminate application on natural environments for the control of illicit crops (coca, cannabis, poppy). Glyphosate has been considered for a long time as a compound with “good toxicological profile,” due to its favorable toxicological and behavioral characteristics in soils and waters. However, several studies from recent years are indicating that glyphosate is not as harmless as was commonly believed (Lévesque and Rahe,1992; Wolfenbarger and Phifer, 2000; Bulcke, 2001). Hence the controversy that currently exists about the environmental impact of this compound in Colombia.

The scientific literature related to glyphosate is immense, which shows that it is one of the most studied pesticides in the world, in many aspects (Baylis, 2000). Numerous publications maintain that glyphosate is a non-residual herbicide in the soil and surface of plants and that it degrades relatively quickly in the soil (Hance, 1976; Shoval y Yariv, 1979); In addition, because its adsorption is very strong in soils, its leaching is considered very limited (Baird et al., 1971; Sprankle et al., 1975b; Rueppel et al., 1977; Hensley et al., 1978) However, glyphosate and its metabolite AMPA present themselves in surface water, and glyphosate in groundwater has also been found in recent years. Studies carried out by the malherbology area of ​​the Faculty of Agricultural Sciences of the National University of Colombia, at its Bogotá campus, demonstrated at the laboratory level, that the herbicide glyphosate marked with carbon fourteen, applied for the control of weeds in rice cultivation in the department of Tolima, is absorbed to great extent in clays 2.1, presenting a half-life of up to 30 years in these soils (Cuervo, 2007).

Glyphosate belongs to the amines chemical group, and it is a non-selective herbicide of systemic post-emergent action, directly applied on the foliage and absorbed by the leaves; It is translocated throughout the plant, mainly via phloem. The herbicidal action of glyphosate, non-selective and broad spectrum, is based on the inhibition of the activity of the enzyme 5-enolpiruvilshikimo-3-fosfo synthase (EPSP), a key enzyme in the shikimate path that leads to the synthesis of the aromatic amino acids phenylalanine, tyrosine and tryptophan, and other products that are also synthesized by the biosynthetic pathway of shikimate, such as lignins, alkaloids and benzoic acids that are necessary for the growth of plants. The shikimate pathway is found in all plants, algae, bacteria and fungi, which could suggest an inhibitory effect on these organisms by glyphosate.

The degradation of glyphosate occurs mainly by the action of soil microorganisms, both in the soil and in aquatic environments, and both aerobically and anaerobically. Thus, the rate of degradation of the herbicide in the soil is related to the microbial activity and the factors that affect this activity. The degradation of this compound depends then on the type of soil, the texture, the organic matter content and the types of microorganisms in the soil.

Studies from the National University of Colombia have shown that the herbicide marked with carbon fourteen, in solution and in the presence of microorganisms from soils with high exposure to the herbicide, react in different ways to contact with the herbicide. In some cases there is an almost total reduction of populations, and in other cases, it was found that there are organisms that tolerate the application of glyphosate at high concentrations, in excess of 50 liters per hectare. The study researchers observed that there are microorganisms that vary according to type of soil, predominant plant species, content of organic matter, pH and moisture content. In soils with forest cover, rich and abundant microorganisms can compete for molecules such as glyphosate, in their search for carbon, phosphorus or nitrogen, all of which are elements present in this type of compound. It was found that soils dedicated to the cultivation of rice for more than 30 years had populations of microorganisms less abundant and diverse, which results in less competition for molecules such as glyphosate. This is because these crops have available nutritive elements for their development and growth , coming from the fertilization of the crops.  

Glyphosate contains a CP bond that is resistant to chemical transformation, and its degradation is therefore a biological process that involves microbial enzymatic activity. Many microorganisms degrade glyphosate producing AMPA or sarcosine; ultimately, the complete transformation of glyphosate leads to the production of water, carbon dioxide and phosphate. The values ​​of glyphosate degradation half life that are reported are very variable, from less than one week to 174 days.

Table. DG50 value of the CFU number/mL of 29 selected microbial morphotypes, isolated from three soils from Tolima department, Colombia.

Acute oral toxicity studies in mammals indicate that the technical glyphosate and its AMPA metabolite have very weak toxicity. Both products are classified in the category of least toxic products (IV) of the US EPA acute toxicity classification system. According to the available data on acute dermal toxicity, the technical product and the Roundup® formulation are considered to be very non-toxic and slightly toxic, respectively.

In past studies, technical glyphosate did not produce irritation for the skin of rabbits but moderate to severe irritations were observed for guinea pigs, after repeated applications. In humans, no primary irritation was observed after the single or repeated cutaneous application of glyphosate  (Doliner, 1991).

The commercial formula of Roundup® developed by Monsanto is a moderate irritant to the skin (Doliner, 1991; Smith and Oehme, 1992). The results also suggest that the irritating potential of Roundup® is mostly related to the surfactant present in the commercial formula. Technical-grade glyphosate in the form of isopropylamine salt, which is the main form used in formulations throughout the world, is slightly irritating to the eyes of rabbits, while the acidic form of the product is a severe eye irritant (USDA,1984).

Technical-grade glyphosate is slightly toxic to fish, and practically non-toxic to aquatic amphibians and invertebrate animals. The formulation of Roundup® is more toxic for freshwater fish and aquatic invertebrate animals.

Aerial Fumigation of Glyphosate in Colombia

Fumigation of unwanted weeds and illicit crops has turned Colombia into a vast territory of experimentation for chemical agents, from long before the beginning of Plan Colombia. Since 1978, successively different formulas have been tried: Paraquat, Triclopyr, Tebuthiuron, Imazapyr and Hexaxinona. The success of these agents, however, was low, and since 1986 the glyphosate herbicide developed by the United States transnational corporation Monsanto, began to be used.

Regarding aerial fumigations of glyphosate for the eradication of illicit crops, this activity is carried out by the Anti Narcotics Directorate of the Colombian Police as established within the Environmental Management Plan (Narcotics Affairs Section, Anti Narcotics Directorate, National Police, Approach to agronomic activity and the problem of coca crops in Colombia, technical document, 2005) and Decree 1843 of 1991 of the Ministry of Health, which regulates the use and management of pesticides in the national territory.

The aerial fumigations affect the surrounding areas of the fumigated crops, areas principally of virgin forest and secondary forest where the great biological diversity of the national territory is found. The drift of the sprayed glyphosate particles can reach distances of up to three kilometers depending on the wind conditions. Glyphosate can therefore reach various areas, affecting the forest vegetation, non-illicit crops, water, people and animals.

“Plan Colombia” established the institutional framework for bilateral cooperation between the Government of the United States and the Government of Colombia to: i) strengthen the operational capabilities of the Public Force against the chain of production of drug trafficking and the fight against the armed groups. Margin of the Law (GAML); ii) leverage a social protection and assistance strategy that would strengthen the economic and social conditions of Colombians; iii) and contribute to the processes of Disarmament, Demobilization and Reintegration (DDR) along with the judicial reforms that were underway in Colombia (National Planning Department, 2006, page 10).

The Plan Colombia, with a duration of 15 years, an investment of 9,600 million dollars by the US Government and an investment of the Government of Colombia of 131,000 million dollars, was divided into three phases:

The first was called the “Plan for peace, the prosperity and the strengthening of the State” (2000-2006). It focused its efforts on strengthening the capacities of the Public Force, the mechanisms of interdiction and eradication of illicit crops, the providing of support for alternative and economic development of the regions affected by the armed conflict, and support for the administration of justice through the implementation of the “Accusatory Oral Criminal System.”

The second phase, framed in the “Strategy for Strengthening Democracy and Social Development” (2007-2009), channeled resources in the fight against terrorism and drug trafficking, the strengthening of justice and the promotion of Human Rights, the opening of markets, integral social development and integral attention to displaced populations (Strategy for Strengthening Democracy and Social Development (2007-2013), 2007).

And the third phase, called the Strategic Development Initiative for Colombia (2010-2015), continued to support the fight against terrorism and drug trafficking, economic and social programs for the vulnerable population, and democratic governance and respect for human rights.

Coca Plant. Caqueta, Colombia.

It is now considered that the aerial application of glyphosate for the eradication of coca plantations has been ineffective, having not decreased coca production over the years of fumigation. It is also highly probable that the aerial fumigations have caused damage to the health of the population residing in the rural areas of the sprayed municipalities, as well as to surrounding ecosystems.

The most frequent symptoms reported by people who were affected by aerial fumigations are: skin breakouts, fever, headache, acute respiratory infection, diarrhea, vomiting, abdominal pain, malaise, dizziness, anguish, fear and panic, sore throat , conjunctivitis and other symptoms.

National researchers have analyzed different cases where the population has been affected by the aerial spraying of glyphosate. These investigations resulted in no conclusive findings as to the effects on health that the exposure to glyphosate used in the eradication of illicit crops had. These findings are due to the fact that many individuals affected by the spraying also work with agricultural crops where they often use the same compound glyphosate. Additionally, blood tests of these individuals have found other substances of greater toxicity than the herbicide used in the “Exposure Program for the Eradication of Illicit Crops with Glyphosate,” running through their systems.

It is also known that there has actually been substantial growth of coca crops in Colombia since fumigations stopped. Specifically coca plantations went from 48,000 hectares in 2013 to about 220,000 hectares at present, which is the stated reason that the current government of president Ivan Duque has returned to aerial applications for the eradication of these crops. The previous government of president Juan Manuel Santos was responsible for suspending these fumigations and the use of glyphosate.  

Coca growers see the jungles of Colombia as a favorable place for the establishment of coca crops, preferring the zones of the Amazon, the south pacific littoral, and the Sierra Nevada de Santa Marta. The aerial applications have generated the displacement of areas of cultivation into new areas of virgin forest, causing increased deforestation and incalculable ecological damage, which is only deepened by the further applications of the broad spectrum herbicide glyphosate. Within these virgin forests, glyphosate kills the native flora, contaminates the water and affects the health of animals and surrounding communities.


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Edited and translated by Daniel Henryk Rasolt