Plan Colombia's Environmental Impacts, Report to U.S. Congress

Aerial herbicide spraying not proven safe for the environment


Anna Cederstav, AIDA (510) 550-6700,


Astrid Puentes, AIDA (5255) 52120141,

In December, the Colombian government violated a bilateral accord with Ecuador by spraying a mixture of herbicides intended to destroy coca crops within 10 kilometers of the Ecuadorian border. To justify the spraying, Colombia relied on studies by a team from the Inter-American Drug Abuse Control Commission (CICAD) of the Organization of American States (OAS), claiming that the spray mixture is safe. However, an independent review of CICAD’s  recent studies, released to members of the U.S. Congress today, shows that the pesticide mixture being sprayed has not, in fact, been proven safe for the environment, and that Ecuador has substantial cause to oppose the spraying.

According to the Interamerican Association for Environmental Defense (AIDA), the first CICAD Environmental and Human Health Assessment of the Aerial Spray Program for Coca and Poppy Control in Colombia, released in 2005, did not assess many of the greatest potential ecological and human health risks posed by the aerial eradication program in Colombia. Because of these omissions and the potential environmental risk of the spraying, the U.S. Congress requested further studies to better assess whether the mixture is truly safe for the environment. 

Preliminary results from the follow-up studies, released in August 2006, show that the mixture is indeed potentially harmful to the environment, and particularly to amphibians — the spray mixture killed 50 percent of the amphibians exposed in less than 96 hours. According to Earthjustice scientist and AIDA’s Program Director Anna Cederstav, "Contrary to what is argued by the government, this study shows sufficient cause for concern to suspend the sprayings due to potential environmental impacts, especially considering that Colombia has the second highest amphibian biodiversity in the world and the most threatened amphibian species."

Many other key questions about the environmental impacts of the spraying also remain unanswered, despite the U.S. Congressional mandate to conduct the studies. For example, the State Department has not provided adequate information about the location of and risk to sensitive water bodies and has done nothing to address whether other threatened species are likely to be harmed. Without these determinations, the claim by the Colombian government that it is safe to spray along the Ecuadorian border is misinformed. 

"Given the number of unanswered questions about the safety of the spraying, and considering the precautionary principle and the international obligation not to cause impacts to the territories of other States, the Colombian government should halt spraying immediately, and instead implement more effective and environmentally safe alternatives for coca eradication," said Astrid Puentes, AIDA’s Legal Director.

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