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Environmental Effects (page 3)

By design, broad-spectrum herbicides such as glyphosate kill a wide range of plants; thus they may destroy rare plant species and disrupt habitats. Since Colombia is one of the world's biologically richest countries19, the threat from spraying is particularly great.

  • Colombia is home to the greatest number of bird species in the world, with 60% of the bird species in South America and 19% of the bird species found worldwide; Colombia has 55,000 plant species, the second highest number of plants in the world. (20) Many of Colombia's plant, bird, and other species are found nowhere else, so the destruction of their habitats could well mean their extinction.
  • Studies show that glyphosate formulations have toxic effects on aquatic organisms including fish, amphibians, insects, crawfish and water fleas. Glyphosate can also affect soil organisms including earthworms, fungi, and microbes. A New Zealand study showed that glyphosate significantly affected growth and survival of earthworms; several studies have found that glyphosate can enhance the growth of disease-causing fungi; and one recent study found that glyphosate can interfere with beneficial mycorrhizal relationships between fungi and plants. (21)
  • The spray campaigns also lead to habitat loss when farmers respond to the destruction of legal or illegal crops by clearing new areas of previously undisturbed forest. The Colombian Human Rights Ombudsman has described a process of "triple deforestation," whereby forest clearing for coca production is followed by poorly regulated spraying which affects forest land and legal food crops. The third wave of deforestation comes when the small farmers move deeper into the forest to new areas to grow both coca and food for their families. (22)

Calls for an Alternative

Governmental, intergovernmental, and civil society sources in Colombia, the U.S., and Europe have called for an alternative to the spray campaigns. All share a common concern that the spray campaigns are damaging the health and livelihoods of Colombian citizens and damaging delicate tropical environments. For example:

  • The governors of the six provinces most affected by the spraying have called for a halt to fumigation and propose voluntary manual eradication of coca crops as an alternative. (23)
  • Colombia's Comptroller-General, Carlos Ossa, has called for a halt to spraying until environmental effects can be measured, and proposed that greater emphasis be put on economic and social programs to encourage farmers to switch to legal crops. (24)
  • Colombia's Human Rights Ombudsman has called for the suspension of aerial spraying pending the development of plans to protect alternative economic projects, population centers and water resources, and the creation of contingency and compensation plans. (25)
  • The UN Drug Control Programme's representative in Colombia and Ecuador, Klaus Nyholm, argues that aerial eradication is neither just nor efficient. Nyholm has called for a halt to the spraying of small producers and for a program of voluntary manual eradication. (26)
  • In August 2001, over 100 physicians, scientists, and other professionals signed an open letter to the U.S. Senate expressing concern about environmental and human health effects of the spray campaigns. The signatories express concern that "we are exposing ecosystems and citizens of another country to a toxic chemical mixture, while failing to disclose the composition of the mixture and the conditions of exposure. (27)

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19 William Eichbaum (Vice-President, Endangered Spaces Program, World Wildlife Fund), letter to Senator Russ Feingold, November 21, 2001.

20 Colombian Ministry of the Environment web page:, visited March 1, 2002.

21 See literature review in Jeremy Bigwood, "A Brief Overview of the Scientific Literature Regarding Reported Deleterious Effects of Glyphosate Formulations on Aquatic and Soil Biota," document prepared for the Ministry of the Environment of Ecuador, March 6, 2002. Available at, visited March 18, 2002.

22 Jose Fernando Castro Caycedo, Nelson Caicedo Rodríguez, Luis Fernando Maldonado Guerrero, and others. Los Cultivos Ilícitos, Política Mundial y Realidad en Colombia. Defensoría del Pueblo. Bogotá. August 2000. pp. 88-89.

23 Juan Forero, Poor Region's Governors in Colombia Unite to Oppose Drug Plan. New York Times (May 6, 2001).

24 Michael Easterbrook, "Government Study Raises Doubts on Drugs," Associated Press (September 2, 2001).

25 Eduardo Cifuentes Muñoz, Colombian Human Rights Ombudsman, letter to Rómulo González Trujillo, Colombian Minister of Justice (July 12, 2001).

26 "ONU Critica Fumigación Aérea," El Tiempo, Bogotá (July 24, 2001).

27 Open Letter to the U.S. Senate, available at