Updated Report on Chemicals Used in the Colombian Aerial Eradication Program

Report on Issues Related to the Aerial Eradication of Illicit Coca in Colombia
Bureau of International Narcotics and Law Enforcement Affairs
December 2003

On September 4, 2002, the Department of State submitted to Congress the Secretary of State's determination and report to Congress on issues related to the eradication of illicit coca in Colombia in accordance with the FY 2002 Foreign Operations, Export Financing, and Related Programs Appropriations Act (P.L. 107-115). That document contained an explanation of the chemicals and methods used for the eradication of coca in Colombia and the safeguards in place to minimize the risk of harm to human health and the environment. It also contained the results of the Department of State's consultations with the United States Environmental Protection Agency (EPA), including EPA's analysis of the risks to human health and the environment that might be posed by coca eradication.

The Government of Colombia and the Department of State have implemented several changes in the program to address concerns raised by the EPA analysis. The first section of this document reviews the Department of State response to EPA's 2002 recommendation for additional controls for the spray program. Sections two and three explain the changes introduced by the Government of Colombia and the Department of State to respond to EPA and Congressional concerns about other aspects of aerial eradication in Colombia. A fourth section describes the changes in chemical composition and spraying methods since the Department of State's 2002 report. The final section reviews the chemicals and methods used for opium poppy eradication in Colombia, a part of the program that Congress did not ask the Department of State or EPA to address in FY 2002.

1. EPA Recommendation to Change Glyphosate Product Used by the Program

The EPA made one direct recommendation to the Department of State related to spray program controls in its "Office of Pesticide Programs Details of the Consultation for Department of State: Use of Pesticide for Coca Eradication Program in Colombia." On page 12 of that document, EPA recommended that "...due to the acute eye irritation caused by the concentrated glyphosate formulated product and the lack of acute toxicity data on the tank mixture, the Agency recommends that DoS consider using an alternative glyphosate product (with lower potential for acute toxicity) in future coca and/or poppy aerial eradication programs." This was addressed to the possible risk of splashing the full-strength glyphosate into the eyes or onto the skin of persons filling the spray tanks on the airplane. It was not directed at potential risk to persons exposed to the spray mixture as actually applied by the planes.

At the time that EPA made this recommendation, there were no suitable replacement glyphosate formulations registered for sale and use in Colombia that offered lower potential for acute eye irritation. The Department of State worked with the program's glyphosate supplier to identify and to register for sale and use in Colombia a formulation of glyphosate with reduced potential for eye irritation. As soon as that product could be registered for sale and use in Colombia, the Department of State began to purchase it for use in the spray program and it remains the formulation used today.

Like the previous formulation, the new formulation is also registered with the EPA for sale in the United States for non-agricultural use. It also contains 41 percent glyphosate salt and 59 percent inert ingredients. Like the previous formulation, the formulation now used is made from a base material (glyphosate technical) that is produced by a manufacturing plant that is registered in the United States even though the formulation is produced and sold in Colombia. The glyphosate formulation now used is mixed with water and surfactant in the same proportions as the previous formulation to form the coca spray mixture.

The difference between the formulations is that the current product has an overall category III toxicological rating ("mildly toxic") on the scale used by the EPA, whereas the previously used glyphosate formulation was rated category I ("highly toxic"). The toxicity reduction is due to a change in the surfactant used in the glyphosate formulation. Of course, these ratings refer to the toxicological profile of the glyphosate formulations in their point of sale, undiluted form, and not the spray mixture (water, glyphosate formulation, and surfactant) that exits the spray aircraft.

The Department of State took these steps in part to address public concerns about the toxicity of the spray mixture and allegations that the combination of glyphosate and surfactant would pose a threat to human and environmental health. In that regard, the Department of State also contracted with an independent United States laboratory to determine the toxicity of the spray mixture (e.g., the glyphosate formulation with water and surfactant added), exactly as it is mixed in the field. Because final drafts of those toxicology tests were not completed in time for EPA's assessment in 2002, copies of the toxicology tests on the spray mixture currently used for coca eradication are enclosed as Attachment A. These tests show that the spray mixture rates a category III ("mildly toxic") for eye irritation and category IV, or "slightly toxic," in all other categories (e.g., acute oral, acute dermal, acute inhalation, skin irritation, sensitization).

2. EPA Advice Regarding Tracking Reported Health Complaints

EPA's "Office of Pesticide Programs Details of the Consultation for Department of State: Use of Pesticide for Coca Eradication Program in Colombia" also advised (on page 32) that: "(p)rospective tracking of reports of health complaints, documenting times of exposure and onset of symptoms, are recommended during future spray operations to evaluate any potential health effects and ameliorate or prevent their occurrence." Although this recommendation is not related to spray program controls, the Department of State has increased its efforts to track reported health complaints and to investigate any possible connection between any such complaints and the eradication of illicit crops.

The spray program tracks human health complaints in two ways. The first is to initiate an immediate investigation, often including clinical evaluation of the patient(s), upon notice to the U.S. Embassy of a problem. The Embassy's Narcotics Affairs Section (NAS) learns about cases through letters directed to the Embassy or GOC entities, from local counternarcotics base commanders, and from the members of the media. To investigate complaints of toxic exposure allegedly caused by spraying, NAS retains the services of two of Colombia's leading toxicologists, including the director of Colombia's national poison control center, the Uribe Cualla Centro de Asesoramiento Toxicol�gico.

Since submission to Congress of the FY2002 "Report on Issues Related to the Eradication of Illicit Coca in Colombia," two such complaints have been reported to the U.S. Embassy. In September 2002, the Embassy received a complaint of multiple cases of poisoning from spraying of coca in Puerto As�s (Putumayo department). A visit to the hospital and interviews with doctors there revealed no cases of poisoning or illness attributable to spray chemicals. The toxicologist learned of two hospitalized children who could have been the source of the complaint, and he reviewed their cases. One of those children was suffering from poisoning by an organophosphate insecticide. The other child was suffering from asthma. An English language version of the toxicologist's report from this investigation is enclosed as Attachment B.

In February 2003, a news report in the Bogot� daily "El Tiempo" attributed the spread of tuberculosis and cases of harelip and cleft palate in newborns to aerial spraying of coca in Tib� (Norte de Santander department). A toxicological review showed cleft palate and harelip to be a genetically inherited defect that has never been reported in humans as a result of exposure to any chemical substance. Tuberculosis is an infectious disease passed from person to person, and is also unrelated to any potential exposure to spray chemicals.

The Government of Colombia and the U.S. Embassy Bogot� have also taken a proactive approach to investigating any human health concerns manifest in areas where the spraying takes place. Both governments have collaborated to create a robust Medical Civic Action Program (Medcap) to search out cases of harm to health allegedly caused by the spraying. During these public health interventions that are timed to take place in areas where coca eradication has recently taken place, U.S. Embassy-contracted toxicologists talk to patients and talk to local medical personnel, looking for spray-related cases. As outlined in the chart below, a total of 1,029 patients made themselves available for Medcap medical personnel, had their medical conditions assessed, and received complimentary health care. Although Medcap personnel have encountered cases that were claimed to be spray-related, reviews of these cases have determined that events unrelated to eradication spraying had caused them. Through Medcap and other medical investigations, the U.S. Embassy has never found an instance of spray-related harm to human health. This is an ongoing program and the next Medcap is planned for the end of April in Caquet�, a few weeks into the spray campaign in that region.


Place and Date
Patients Assessed

Cartagena del Chair� (Caquet�)
May 11, 2002


Solano (Caquet�)
August 7, 2002


Santa Ana (Putumayo)
September 21, 2002


Puerto As�s (Putumayo)
November 9, 2002


San Vicente del Cagu�n (Caquet�)
February 1, 2003


To further address public and Congressional concerns about the possibility of human health and environmental harm potentially caused by spraying, the Department of State is working with the Government of Colombia and Garzon Ingenieros Asociados Ltda, an accredited Colombian laboratory, to analyze water taken from areas where the spray program operates. Technology for monitoring soil is not available in Colombia, so the Department of State is working with the Government of Colombia and the U.S. Department of Agriculture Agricultural Research Service to analyze soil samples at the USDA/ARS laboratory at the University of Mississippi. The Department of State is paying for technicians from two Colombian government laboratories and the Ministry of the Environment to travel to Mississippi in April to learn how to perform the analysis. The soil and water analyses will determine the degree of persistence of glyphosate and its byproducts in Colombian soil and water, in the unlikely event there is something unique about Colombian soil and water that would invalidate the many studies done on the residual effects of glyphosate in other parts of the world. The Department of State, the Government of Colombia and a private Colombian university (Universidad de Los Andes) are developing demonstration plots in the five distinct environmental regions of the country to study glyphosate persistence and the regeneration of natural vegetation and other ecological dynamics following aerial eradication of illicit crops.

3. EPA Comment Regarding Spray Drift

Although not addressed to the Department of State as a recommendation, EPA also noted in its consultation with the Department of State some concern for spray drift and the potential for non-targeted, desirable vegetation to suffer from the spraying of nearby coca (or opium poppy). Informed of EPA's and Congressional concern, the Department of State and the Government of Colombia have incorporated several measures into the spray program to assist us with evaluation and control of spray drift.

The first of these steps was to reinforce the environmental safety component of spray pilot training. All pilots, both fixed wing spray pilots and rotary wing escort helicopter pilots, will receive briefings on the potential negative impact that spraying may have on the environment and techniques to minimize potential collateral damage to legal crops and the environment. These briefings will be conducted semi-annually, will emphasize the unique aspects of the Colombian operational theatre, and will solicit feedback from pilots on techniques to maximize application effectiveness and avoid damage to non-target vegetation. An outline of this briefing is included as Attachment C. Search and rescue helicopter crews that accompany each spray flight have also been directed to monitor drift patterns from above. They now assist in ensuring that spray does not drift beyond target crops and notify the spray aircraft flight lead when conditions might merit canceling a spray flight. A copy of the directive from the Department of State's Bureau of International Narcotics and Law Enforcement Affairs (INL) Office of Aviation to the eradication contractor that formalizes these new spray regulations is included as Attachment D.

The Department of State's Assistant Secretary for INL also directed the team of United States Department of Agriculture (USDA) and Government of Colombia scientists, responsible for the ground truth verification missions, to incorporate an analysis and quantification of overspray into ground truth verification exercises. While past verification missions sought out and noted cases of overspray, documenting the existence and extent of any damage to crops or foliage not targeted for eradication, this is now a formal component of the ground truthing exercise. The most recent ground truth verification mission (December 9-20, 2002) found that incidences of overspray were minor. The USDA Agricultural Research Service report from this verification exercise has not yet been completed, and INL will forward a complete copy to EPA as soon as the Department of State receives the report.

4. Changes in Chemical Composition and Spraying Methods Since 2002 Report

Apart from changing to a more benign formulation of glyphosate spray mixture, as discussed earlier, there have been no changes to any of the components of the spray mixture. For some time in 2002, the Government of Colombia lowered the application rate of glyphosate for coca eradication from the traditional application rate of 10.4 liters per hectare to 8.0 liters per hectare. After extensive ground truth evaluation, it was determined that the lower rate was ineffective for killing coca. Thus the application rate was returned to its former rate of 10.4 liters per hectare, which was the rate reported in the Department's Report on Issues Related to the Eradication of Illicit Coca in Colombia in 2002 -- the rate that EPA evaluated when analyzing the potential for risks of adverse effects on human health and the environment posed by the coca eradication program.

The only changes in the methodology used to spray coca since the time of the last report is the addition of a new type of spray aircraft to the spray fleet. Four Air Tractor Model 802 (AT-802) aircraft are currently being used to spray coca, and another four will be delivered this year. These aircraft are manufactured in the United States for agricultural crop spraying and utilize the identical nozzles (same brand and diameter) in the identical configuration (nozzle angle, droplet size, calibration methods) as the OV-10 and T-65 spray aircraft. AT-802 flight speed during eradication operations is 165 m.p.h.

5. Differences Between Opium Poppy Spraying and Coca Spraying

The Secretary of State was not required to determine and report to Congress on any aspects of the opium poppy eradication program in FY2002, and thus the Department did not provide information to EPA on the chemicals and methodology of poppy spraying. Like the coca spray mixture described in the "Report on Issues Related to the Eradication of Illicit Coca in Colombia," the opium poppy spray mixture contains three components: water, an EPA-registered formulation of the herbicide glyphosate, and a surfactant (Cosmo-Flux 411F). Because the opium poppy is not a woody, hard-to-control species like the coca bush, opium poppy eradication uses a spray mixture with a substantially lower glyphosate content than the spray mixture used for coca eradication (see Attachment E). For opium poppy spraying, water, formulated glyphosate, and surfactant are combined into a spray mixture in the following percentages: 94 percent water, 5 percent glyphosate formulation, and 1 percent Cosmo-Flux 411F. This diluted mixture is applied to opium poppy at the rate of 50.0 liters/hectare (or 5.46 gallons per acre). This application rate is within the glyphosate manufacturer's label recommendations for both the amount of concentrated formulation per acre and the amount of total spray volume per acre.

Opium poppy spraying differs from coca spraying in several ways. Because Colombia cultivates much less opium poppy than coca and spray program resources are limited, aircraft spray much more coca than opium poppy, therefore expending more spray chemicals in coca growing areas than in areas where opium poppy is cultivated. For example, in 2002, eradication aircraft sprayed totals of 122,700 hectares of coca and 3,000 hectares of opium poppy. Opium poppy is generally cultivated in plots that are smaller than the average coca field. While difficult to quantify precisely, opium poppy fields generally range from 0.5 to 5 hectares. Opium poppy is ordinarily cultivated at a higher altitude than coca, and thus opium poppy often is cultivated and sprayed in hilly to mountainous terrain. For these reasons, the T-65 is the only aircraft used to spray opium poppy because it has a smaller wingspan (and spray swath) than the OV-10 or AT-802 and because it is a more agile aircraft capable of staying close to the ground in more steeply graded, rugged terrain.

Because of the challenges of mountain spraying, pilots undergo an extended training program before they are qualified to perform actual opium poppy spray operations in Colombia. As the Department of State reported in 2002, coca eradication pilots must have approximately 3,000 total flight hours before they are considered for the spray program and can receive preliminary training in illicit crop eradication. Most of these pilots also have at least 1,500 hours of commercial aerial application (crop dusting) experience. In addition to these requirements, opium poppy spray pilots must undergo 40 hours of follow-on training specific to the topography, wind conditions, and cloud cover that they will experience in their area of operations.


  1. Toxicological testing results for coca spray mixture (Purity Analysis for Glyphosate, Acute Oral Toxicity Study, Acute Dermal Toxicity Study, Acute Nose-Only Inhalation Toxicity Study, Primary Eye Irritation Study, Primary Skin Irritation Study, Dermal Sensitization Study).

  2. "Investigative Report on Cases of Possible Human Health Effects in Puerto As�s," Jorge Hern�n Botero Tob�n, M.D. Bogot�, Colombia, September 19, 2002.

  3. Outline of Spray Pilot Semi-Annual Briefing.

  4. Memo from INL Office of Aviation Director of Operations to DynCorp Operations Manager re: Aerial Eradication Procedures, December 13, 2002.

  5. Coca and Opium Poppy Spray Mixtures Comparison Graph.