Expected ecological effects of herbicide spray campaigns in Colombia

Many individuals and institutions have expressed concern about damage to ecosystems resulting from the spray campaigns. For example, in 2001, a report from Colombia’s Comptroller- General's office reported that the spray campaigns were damaging the environment and failing to curb drug production. The report stated that “the majority of the environmental damages are irreversible,” and called for a halt to spraying until scientists were able to study the herbicide's environmental effects.

These effects of glyphosate herbicides can vary significantly depending on the circumstances of exposure. The U.S. Embassy states in a November, 2001 "fact sheet" that the herbicides used in the spray campaigns are "practically nontoxic to fish."64 In fact, there is reason to believe that the mixture as sprayed in Colombia can have serious adverse effects on fish life, especially since exposure circumstances in Colombia are quite different from those under which tests have been conducted. Effects of glyphosate and Roundup on fish vary widely depending on species affected, temperature, and other factors. In general, formulations including a surfactant are more toxic to fish than pure glyphosate. The toxicity of surfactant ingredients can vary according to the hardness and acidity of the water where it is sprayed. Perhaps most importantly for tropical regions, toxicity of Roundup to some fish has been found to increase with increasing water temperature. 65 Little to no information is available on the likely effects of the specific exposure conditions that exist in Colombia, but it is plausible to expect that effects on fish would be more serious than is predicted based on experiences in temperate climates.