Spray mixing and handling:
The commercial glyphosate formulation, Cosmo-Flux 411F,
and water are mixed at forward air bases by mixers/loaders who are members
of the Colombian National Police (CNP). The mixers/loaders are trained by
the CNP, the U.S. Embassy’s spray advisor, and by designated spray pilots.
They are trained on the relevant precautions for handling the chemicals in
the spray mixture, first aid, and use of personal protective equipment that
applicators and other handlers of glyphosate in its concentrated formulation
must wear. These include long-sleeved shirts and long pants, waterproof
gloves, shoes and socks, and protective eyewear.
Storage and disposal of spray mixture:
Special care is taken in the management of the commercial
glyphosate formulation, which is more concentrated than the spray mixture.
Appropriate measures are taken to ensure that glyphosate is not allowed to
contaminate water, foodstuffs, or natural areas through its storage or
disposal. Storage is in manufacturer-approved plastic barrels in covered
areas with good ventilation, away from water sources. At the main spray
bases, chemical storage is in a concrete storage shelter approximately 50
centimeters high with a 10-degree incline for the collection of any residues.
In addition, sawdust, sand, dirt, clay or other absorbent material is
readily available for immediate use in case of glyphosate spills. A drainage
system, designed to prevent water contamination via run-off or leaching into
the ground, collects water storage, mixing, and loading areas in trenches
that carry it to a stabilization pools, which are eventually discharged into
a specially selected lot to facilitate natural degradation.
Aircraft and spray equipment:
Aviators currently spray coca with the single-engine T-65
"Thrush" aircraft built by the Ayers Corporation for agricultural spray
operations and with the twin-engine OV-10D "Bronco" aircraft converted from
a military observation aircraft to an aerial spray aircraft. INL is
currently taking delivery of a third type of spray aircraft, the Air Tractor
AT-802, which is a single-engine agricultural spray aircraft similar to the
T-65.
The spray nozzles are standard, agricultural nozzles
selected and adjusted to minimize the number of small droplets that can
drift downwind from a sprayed coca field. These nozzles produce a volume
mean diameter (VMD) between 300-1,500 microns. This droplet size was reached
after considerable INL and USDA testing and is consistent with the label
instructions recommending coarse sprays that are less likely to drift. The
aircraft spray systems are electronically calibrated to disperse a specified
quantity of gallons of spray mix per hectare, compensating for variances in
ground speed. These are calibrated upon installation and are checked each
day during the mechanic’s daily inspection and the pilot’s preflight
inspection. In addition, during actual spray operations the pilot monitors
the spray system by observing the readings of the spray pressure and the
spray flow rate gauges. Onboard computer and digital global positioning
systems (D/GPS)-driven equipment (SATLOC and Del Norte) automatically record
each aircraft’s actual flight parameters, including differential-GPS track,
airspeed, altitude (mean sea level), application rate, and precise
geographic location (longitude and latitude coordinates) at the time of
aspersion. This allows precise evaluation of each spray event in order to
ensure that spraying is conducted within proper target areas and within
specified parameters. As part of the end-of-mission check, the mission
planner and pilots review the spray logs for any inconsistencies in the
recorded spray data.
Spray pilots:
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. The INL Air Wing contractor trains the spray pilots who
are Colombians, third-country nationals, and U.S. citizens. Eradication
training focuses extensively on the visual identification of coca fields
from the air as well as the technical aspects of crop spraying.
Reconnaissance:
Detailed aerial reconnaissance of cultivation areas
precedes all spray missions. Aerial reconnaissance is performed using a
multispectral digital imaging system (MDIS) that identifies crop type
through the reflected sunlight in the infrared portion of the
electromagnetic spectrum. This airborne camera system is calibrated daily
and linked to global positioning systems (GPS) equipment that enables fields
to be geo-referenced and accurately plotted onto aviation maps for mission
planning purposes. As explained below, this equipment is for mission
planning and reconnaissance and is not in any way a substitute for positive
visual identification of coca fields by the spray pilot during the actual
spray mission.
Most of Colombia’s coca crop is cultivated in the lowlands
east of the Andes; here, the terrain is generally flat or marked by gentle,
rolling hills. The more agile T-65 is used for spraying in areas with
steeper topography. Coca is often grown in monocrop fields cut out of the
triple canopy rainforest of the Amazon Basin. In this context the precision
of the pilots is crucial, as is the use of a herbicide mixture that allows
for rapid restoration of natural vegetation once the coca has been killed.
The reemergence of native vegetation occurs very quickly after glyphosate
application, ensuring that soil erosion will be minimal.
Spray parameters:
Spraying is conducted in Colombia under rigid parameters
laid out by the GOC’s Environmental Auditor to the spray program. Missions
are cancelled if wind speed at the airport is greater than 10 m.p.h., if
relative humidity is below 75 percent, or if
temperature is over 32º Celsius (90º Fahrenheit) - to avoid drift that might
come from a temperature inversion. Spray missions are planned so as to avoid
spraying wet coca; the goal is to have no rain on the targeted fields from
two hours before to four hours after the spraying. Spraying most often takes
place in the morning when weather conditions are favorable in the spraying
area, although spraying can take place any time of day when the above
conditions are satisfied. Poor atmospheric conditions often are the cause of
mission cancellations. For example, in 1998 and 1999, spraying took place on
an average of 125 days out of the year. During the other 240 days, the spray
planes were grounded, with the majority of cancellations due to bad weather.
While flight lines are programmed using the reconnaissance
procedures outlined above, pilots are instructed and trained to activate
their aircraft spray systems only when they have positively identified coca
directly in their spray line. Spray planes are under continual risk from
hostile ground fire, yet the pilots spray as low over the coca fields as
obstacles (e.g. trees) and security conditions will permit. The altitude
above spray targets while spraying is normally less than 100 feet. Under the
conditions in which the aerial eradication program is carried out in
Colombia, spray pilots face great risks. Over the seven years of the aerial
coca eradication program in Colombia, three spray pilots have lost their
lives by striking their aircraft against the ground or trees while trying to
spray as close to the illicit crop as possible.
The pilot of each eradication aircraft is responsible for
deciding when damage to non-target foliage is likely to occur and to take
every measure to avoid such collateral damage and spray only within the
boundaries of the coca field. Pilots are licensed and trained to be
conscious of wind direction and speed during spray operations to avoid
unintentional damage to any legal crops. According to Colombian law, food
crops that are interspersed with coca are subject to spraying. Nonetheless,
great care is taken to avoid spray damage to legal crops and the spraying of
any area that does not contain coca. While every effort is made to minimize
human and mechanical mistakes, occasional errors are unavoidable. The GOC
has implemented improved procedures to investigate claims of spraying of
legal crops and to compensate owners if damage is found to be credible.
Spraying and human and environmental health:
Glyphosate is one of the most widely used agricultural
herbicides in the world. It has been tested extensively in the United States,
Colombia, and elsewhere. EPA approved glyphosate for general use in 1974 and
re-registered it in September 1993. In its latest comprehensive review of
studies on glyphosate, the EPA concluded that proper use of glyphosate, as
permitted in the U.S., would not cause unreasonable adverse effects in
humans or the environment.
The product label advises that the concentrated
formulation of the glyphosate product causes irreversible eye damage, is
harmful if swallowed or inhaled, and may cause skin irritation. These
precautionary statements are determined according to EPA policy and are
based on the results of testing on laboratory animals. INL does not believe
that the spray program exposes humans who may be present in a sprayed field
to such risks. This is because the irritation and toxicity potential of the
individual ingredients are reduced when diluted during mixing (the final
product is approximately 75 percent water) and the mixture is dispersed when
sprayed. Thus humans who may be present under the swath of the plane are not
exposed to levels that approach the commercial glyphosate formulation in its
concentrated, undiluted form. The symptoms of such exposure are likely to be
short-term and reversible. Furthermore, any one individual field is unlikely
to be sprayed more than one time in a year, lowering the levels of repeated
potential human exposure.
To minimize human exposure to the spray mixture, pilots
are instructed to avoid flights over towns and populated areas and, during
spray missions, to avoid spraying near people, homes, or occupied buildings.
Studies on livestock (cows, goats, and chickens) show
livestock absorb limited amounts of glyphosate. Permitted levels of
glyphosate in/on crops and livestock for human consumption are published in
the Code of Federal Regulations, Title 40 (40 CFR), Section 180.364. EPA has
concluded that consumption of crops treated with glyphosate and livestock
fed with forage treated with glyphosate in the U.S. does not pose a dietary
concern when residues are below these published tolerances. With respect to
environmental impact, EPA concluded, based on required and available
scientific studies, that glyphosate is not persistent in soil, does not
build up after repeated use, and is biologically degraded over time by soil
microbes. Because it binds tightly with the soil, glyphosate is unlikely to
leach into underground drinking water. These qualities make glyphosate a
well-suited herbicide for use against coca in Colombia.
Studies have shown glyphosate itself to be "practically
non-toxic" to fish, however some glyphosate end-products may contain other
ingredients that may increase the toxicity to fish when they are exposed. In
accordance with the instructions on the product label, pilots are instructed
to avoid all bodies of water when spraying coca.
Eradication oversight:
Spray pilot oversight is carried out by several entities.
Pilot performance is monitored by the GOC’s Environmental Auditor, the
Colombian National Police (CNP), INL’s Office of Aviation, the Narcotics
Affairs Section (NAS) of the U.S. Embassy, Department of State contractor
personnel, USDA weed scientists, and the GOC’s National Directorate of
Dangerous Drugs. The Environmental Auditor, the CNP, and the contractor
personnel are continually on-site in the bases or airports from which the
spray planes operate and in most cases accompany the spray missions
themselves. All of the above-mentioned offices actively participate in the
ground truth verification of randomly selected, previously sprayed fields.
These verifications usually take place twice a year. During this process,
one of the important elements is an assessment of potential overspray or
non-target drift, essential indicators of spray pilot (and herbicide)
precision. These ground truth verification missions have found very few
instances of spray pilot error and have reported that pilot accuracy is
excellent and overspray minimal.
Unfortunately, human and mechanical error is possible and
mistakes are made on occasion. In the past, many complaints of erroneous
spraying of legal crops have proven groundless after subsequent
investigation. However, INL believes that the credibility of the spray
program is enhanced by a speedy and fair review of all complaints and by
just compensation for any legal crops that were indeed sprayed in error.
With support from the United States, the GOC’s process of investigating harm
to legal crops has recently been improved to provide for faster
investigation and resolution of complaints.