Illicit narcotics cultivation and processing: the ignored environmental drama


Illicit coca cultivation and processing
Illicit opium poppy cultivation and heroin refining
Illicit cannabis cultivation


Pages: 9 to 20
Creation Date: 1992/01/01

Illicit narcotics cultivation and processing: the ignored environmental drama

L. ARMSTEAD Technical Program Officer, Bureau of International Narcotics Matters, Department of State, Washington, D.C., United States of America


Drug abuse and the environment are among the most pre- occupying issues in today's world. Up to now, relatively little attention has been given to linkages between these two issues, which are at. first glance unconnected in any meaningful way. More careful analysis identifies major linkages between the environmental impact of illicit drug cultivation, the rapid expansion of illicit cultivation into tropical forest areas, the efforts to eradicate illicit crops and pollution through the processing of raw materials into drugs of abuse. This article reviews those linkages and recommends measures that might be taken to deal with their consequences.


Each year, despite greater international awareness and conservation efforts, more than 11 million hectares of the earth's remaining tropical forests are cleared and converted to other land uses or unproductive land.* Studies show that if current trends continue, the present forest reserves will be consumed in less than 40 years. Considering the fact that more than 75 countries between the tropics of Cancer and Capricorn have control of virtually 100 per cent of the world's tropical forest area, compared with only six or seven countries dominating the temperate woodlands, there is a need for a coordinated worldwide effort to focus increased attention on conservation and restoration of these tropical resources.

*This amounts to an area of 1 to 2 per cent of the world's tropical forests being cleared every year, an area the size of the United Kingdom of Great Britain and Northern Ireland.

Numerous scientific studies conducted to date describe the negative consequences associated with the loss of the world's tropical forest resources. Categorically, these consequences consist of land concerns, such as soil erosion and soil nutrient depletion; genetic concerns including the loss and extinction of entire species of both flora and fauna, which by some estimates represent a rich genetic pool where hundreds if not thousands of species whose benefits to humanity are yet undiscovered; hydrological concerns, which include the loss of watershed and the sedimentation or siltation of waterways leading to lowland flooding, the loss of agricultural land, and even further ecological imbalance; socioeconomic concerns, such as increased hunger, poverty, reduced standards of living and the rapid loss of untold medicinal and pharmaceutical benefits to mankind from the world's forest resources; and finally atmospheric concerns, including the impact upon regional climates and a greater likelihood of both drought and flooding.

Experts attribute deforestation and water pollution in the tropics to population pressures, shifting cultivation patterns, and the extraction of economic resources. Typically, rain forests are cleared to permit the creation of new roads, farmlands and ranchlands; the construction of dams and large-scale hydrological projects; mining and smelting operations; the gathering of fuel wood; and logging for domestic and export purposes. One significant contributor to the forest removal and water and soil pollution in these regions, however, whose impact has gone virtually unnoticed by scientists and journalists, has been the cultivation of illicit narcotic crops - cannabis, coca and opium poppy.

Cultivation of illicit narcotics not only accounts for an increasing share of tropical deforestation, it is also the cause of some of the most severe environmental damage. Growers commonly plant their illicit crops in fragile forest environments in remote areas. Moreover, in some areas the illicit cultivators are often recent migrants from urban centres or other economic pursuits who have moved into the growing regions to take advantage of quick profits. Unlike an indigenous peasant farmer who often has a culturally instilled sense of respect for his land and the environment, narcotics cultivators often have no emotional ties to either farming or the land. Thus, the clearing and cultivation methods of these "opportunistic" illicit drug growers are usually more devastating than those of a true agrarian.

The more severe environmental degradation to tropical forests by illicit narcotics cultivators largely results from the rapid and damaging techniques used to clear the land. Even today, the most widely used forest removal method is manual clearing, commonly known as "slash- and-burn" agriculture, where trees are rapidly felled and destroyed by fire leaving no vegetative matter to stabilize or replenish the soils. Frequently, fields are utilized for only a few years until the initial nutrient sources are depleted. The effects are further exacerbated when the narcotics crops are cultivated on steep-sloped fragile mountain environments where soil is thin and the potential for a high degree of soil erosion is great. Other land-clearing techniques, including both the use of petrol and diesel -fuelled machinery, destabilize the soils and accelerate the rates of soil loss.

Chemicals used by many growers at all stages of illicit drug cultivation and production likewise have a substantial negative impact upon tropical ecosystems and on human population. Growers of illicit crops, in order to clear and maintain their fields, frequently use high levels of fertilizers, herbicides and pesticides. Cocaine and heroin processors each year dump millions of tonnes of toxic chemical substances and waste by-products of the extraction process indiscriminately onto the land and into countless small streams, rivers and water bodies. These hazardous chemical wastes perilously impact upon land as well as water life forms. Ecological experts note that many of the affected tributaries are now almost entirely devoid of many species of plant and animal life. Contaminated water used to irrigate food crops not only compounds the environmental damage but poses a substantial public health hazard.

Illicit coca cultivation and processing

Virtually all of the illicit cocaine produced comes from the Andean regions of three South American countries - Bolivia, Colombia and Peru. More specifically, most of the coca leaf used to produce cocaine is grown either in the Upper Huallaga valley in Peru or the Chapare region in Bolivia. The dramatic expansion of coca cultivation and cocaine processing, largely during the past decade, has caused and is continuing to cause environmental damage the extent of which may never be fully assessed. Systematic removal of mountain and lowland jungle forests for coca cultivation and the construction of illicit airstrips, and the chemical pollution of countless waterways is inflicting irreparable harm upon widespread areas of the Amazon jungle habitat. Although most coca is grown in forests protected by law, the Governments of Bolivia, Colombia and Peru have had considerable difficulty in slowing the rate of deforestation; as a result, some of the most important ecosystems in the upper Amazon basin have been destroyed.

Peru, the world's leading cultivator of illicit coca, is the most important supplier of coca paste and cocaine base to cocaine hydrochloride laboratories in Colombia. Today, the estimated country-wide coca cultivation of Peru is at least 125,000 hectares, significantly more than the amount cultivated by the other two leading coca producing countries, Bolivia and Colombia. While coca is grown in nearly every administrative department in Peru, almost 65 per cent of its cultivation is concentrated in the Upper Huallaga valley, a remote jungle region on the eastern slopes of the Andes near Tingo Maria, some 300 kilometres north-east of Lima.

In the past decade, the Huallaga region of Peru has been transformed from a largely self-sufficient mixed agricultural economy into one of predominately illicit coca. The intensification of coca cultivation in the Huallaga flood plain and adjacent low hills as well as vigorous expansion into highland forest environments is responsible for the annihilation of nearly 1 million hectares of tropical forest resources. A heavy smoke haze covers the Upper Huallaga valley in August and September as growers using centuries-old slash-and-burn techniques methodically remove primitive jungle forests for new illicit coca fields.

Cultivators of illicit coca fields, in their relentless pursuit of fertile growing soils, have recklessly exposed the thin tropical forest soils to increased run-off and erosion. Evidence of the excessive deforestation became painfully apparent during devastating November 1987 floods in central Peru. Torrential rains caused major landslides, blocked roads, and impoverished and killed scores of lowland residents. Post -flood inspect - ion of the Huallaga watershed revealed extensive new sedimentation along rivers and streams throughout the region. The Lima press, calling the deluge "the worst flooding in Peru's history", attributed the damage to "indiscriminate upland deforestation".

Equally tragic, the coca cultivators of the Huallaga region are rapidly eliminating one of the most genetically prosperous ecosystems of the entire Amazon river basin. The United States National Academy of Sciences reports that as many as 300 tree species can be counted in a typical hectare of Peruvian rain forest, in contrast with only 7 to 15 per hectare in an average temperate forest. By comparison, South-East Asian forests average no more than 200 tree species per hectare while those in Central Africa peak at 120 species, thus making the Peruvian Amazon one of the world's more diverse repositories of tree species. Moreover, the vast destruction of Amazonian forests for coca cultivation contributes to the loss of rare plant species from which future pharmaceutical drugs and other human benefits may be developed.

The Huallaga region of Peru may also be the world's richest in all forms of fauna, with documented record numbers of species among butterflies, amphibians, reptiles, birds and mammals, representing a combined latent genetic potential virtually impossible to quantify. However, leading scientists note that if current rates of deforestation in Peru persist, this "genetic frontier" may soon be gone. According to the Global 2000 Report to the President of the United States, "extinctions of plant and animal species will increase dramatically. Hundreds of thousands of species - perhaps as many as 20 per cent of all species on Earth - will be irretrievably lost as their habitats vanish, especially in the tropical forests".

Coca cultivation in Bolivia, the second largest producer in South America, is located in the Yungas region where impressive hillside terracing for coca growing and the chewing of its leaves precede colonial times, and in the more recently developed Chapare region. The Chapare, a semi -tropical area about the size of El Salvador, located approximately 600 kilometres east of the capital city of La Paz, accounts for the majority of Bolivia's illicit cultivation for cocaine production. For many years the farmers of Chapare, who were all immigrants from other regions of the country, successfully produced a variety of food crops including rice, yucca, citrus and bananas. In the past two decades, however, as the international demand for illicit coca escalated, the region rapidly shifted from mixed coca and legitimate crops to a coca-dominated agriculture. Today, the Chapare's extensive switch to coca cultivation now requires the region to import food in order to support its population.

The environmental losses associated with the Chapare's shift to coca cultivation are enormous. Coca growers, more so than legitimate farmers or livestock ranchers, are annually razing thousands of hectares of forests from the alluvial plains and nearby foothills. Ecologists estimate that more than 15,000 hectares of forests in the Isibora Secore National Park, on the border of the departments of Cochabamba and El Beni, have been replaced by coca plantations. Most recently, indifferent coca cultivators have begun methodically destroying the higher hillside forests above the Chapare jungle plain. In these elevated areas, little or no timber is saved, and there is no evidence of forest conservation or reforestation. The destructive slash-and-burn agriculture has changed river flows, stripping off top soils and exposing the underlying sand soils.

Coca planting in the lowland Chapare region as well as the elaborately terraced Yungas and similarly other Andean growing regions in Peru and Colombia, while not always causing major soil erosion, nevertheless contribute to permanent soil ruin. For example, the whole- sale removal of the natural vegetation combined with the negative growth characteristics of the coca bush itself have depleted the basic soil nutrients - nitrogen, carbon, and essential minerals - leaving behind highly infertile soils. In addition, the nitrogen and phosphorous residues from powerful herbicides, pesticides, and fertilizers used by coca growers, magnify the soil sterility. As the lateritic soils harden following the removal of coca bushes, they become extremely hostile to the subsequent growth of other plants. Therefore, even if Government officials in the Chapare, Yungas, or any other growing regions, are successful in reducing or eliminating coca, the possibility of planting alternative crops or effective reforestation on the same lands will be woefully lessened.

Experts estimate that hundreds of thousands of tonnes of chemicals are used annually in cocaine production in the Andean region, roughly representing about 2 tonnes of waste by-products generated for each hectare of illicit coca cultivation. In the process of maceration and washing coca leaf to make coca paste, processors indiscriminately discard enormous amounts of gasoline, kerosene, sulphuric acid, ammonia, sodium carbonate, potassium carbonate and lime, onto the ground and into nearby waterways. Buenaventura Marcelo of the National Agrarian University of Peru, who has studied the toxic effects of chemicals used in coca paste production, writes: "... the rivers and streams of the middle and higher elevations of the Upper Huallaga valley ... are literally flooded, year after year, with vast quantities of toxic waste and pollution". Marc Durojeanni, a former head of the same Peruvian university, writes: "fisheries and all forms of life are almost totally destroyed in the small streams." Similarly, in the Chapare region of Bolivia and the Llanos region of south-east Colombia, millions of litres of used toxic chemicals are irresponsibly discarded into the soil and nearby streams. Recently, paste processors have even found it convenient to hide laboratories in remote natural areas such as Isiboro-Secure National Park, one of the Chapare's most primitive forest reserves.

Colombia, the primary processor of cocaine base and cocaine hydro- chloride, in the Andean region, has incurred immeasurable damage to the ecosystem of the Llanos region from the dumping of chemical wastes generated in the processing. Each year, more than 20 million litres of ethyl ether, acetone, ammonia, sulphuric acid and hydrochloric acid - primary chemicals used to produce cocaine hydrochloride - are discarded from jungle laboratories into the nearby streams and tributaries that feed the vast Amazon and Orinoco rivers. Affected Llanos waterways, like those in the coca-processing regions of Peru and Bolivia, are almost entirely devoid of many species of aquatic, plant and animal life.

Illicit opium poppy cultivation and heroin refining

Environmental degradation - removal of rain forests, loss of soils and their nutrients, watershed pollution, and loss of species diversity - by illicit opium poppy cultivators and heroin producers in many respects is analogous to that inflicted to their environment by illicit coca cultivators and processors in South America. In South-East Asia, hill tribe farmers and other opium poppy growers - sometimes not fully under the control of central Governments - have razed hundreds of thousands, if not millions of hectares of mountain rain forests to support the shifting nature of their agricultural system. Likewise, heroin processors have carelessly discarded unknown quantities of toxic chemical wastes and by-products into the rivers, streams and reservoirs of the region.

Until recently, the mountains and valleys of the Golden Triangle region of the Lao People's Democratic Republic, Myanmar and Thailand provided almost limitless geographic territory for opium poppy cultivators. The mostly primitive forest region, consisting of almost 400,000 square kilometres of mountainous terrain, was sparsely populated by often still nomadic tribes. Unfortunately, the opium poppy plant like much of upland agriculture often depletes the thin forest soils and their nutrients so quickly that slash - and - burn growers, after harvesting as few as two or three crop cycles, clear new forest plots. The cumulative result of the removal of the forest resources by these migratory agricultural practices has rapidly compounded the environmental destruction in the Golden Triangle region.

Heroin production is a multi-step process consisting of the removal of latex or gum from the green opium poppy capsule, the extraction of morphine from latex, and the conversion of the morphine into heroin. The first step, harvesting of the opium gum by the peasant farmer, quite unlike the concluding two steps, is not harmful to the environment. Secondly, morphine extraction performed in very rudimentary shelters beneath jungle canopy requires a number of natural chemicals similar to those used for cocaine hydrochloride production. The process uses a variety of solvents, acids and alkalines including lime and ammonia, tartaric acid and ammonium chloride, as well as alcohol and acetone. Finally, the conversion of morphine into heroin - a chemical reaction called acetylation - requires somewhat more advanced laboratory conditions. Primary chemicals employed in heroin refining are acetic anhydride or other acetylating agents, solvents and hydrochloric acid, and ammonia or other alkalines.

Heroin refining, done in relatively simple jungle conditions analogous to cocaine processing, likewise has devastating effects upon the tropical ecosystems. Whereas in earlier decades the production steps of heroin processing were separated geographically, the opium harvesting and morphine extraction being conducted near cultivation versus the heroin processing near chemical sources in Europe and elsewhere, today's entire production chain takes place in the growing area. Consequently, highly dangerous chemical substances such as acetylating agents as well as dozens of other waste by-products highly toxic to animal and plant life are commonly discarded or seep into nearby waterways. Similarly, heroin refiners at clandestine jungle refineries located near international borders carelessly contaminate regional water resources by their indifferent disposal of poisonous processing chemicals.

Favourable topography, the key geographic factor responsible for the creation of the opium economy in South-East Asia, is one of the best arguments for eliminating opium poppy cultivation. Increasing population pressures combined with diminishing forest resources and associated detrimental effects such as watershed loss and downstream sedimentation are raising environmental issues to new levels of visibility in all South-East Asian countries where opium poppy is grown. The International Union for Conservation of Nature Commission on Parks and Protected Areas recently added Chiang Mai's Doi Inthanon National Park to its list of threatened parks. Its forest reserves, along with Doi Chang Das Wildlife Sanctuary in Chiang Mai Province of Thailand, have been severely damaged by opium poppy cultivation and other human encroachment.

Recently, the Government of the Lao People's Democratic Republic, estimating that its forests are being depleted at a rate of 250,000 to 350,000 hectares per year, initiated an intensive programme to replace slash-and-burn agriculture with more stable (and licit) agriculture. The objectives of all programmes are to preserve the forest environment and offer opium poppy farmers a viable alternative means of livelihood. Officials realize that the eradication of existing fields, without a viable economic alternative, will probably cause some farmers to burn new forest areas in order to continue opium poppy farming.

Elsewhere, the largest remaining tropical forest region of Mexico, located in the south-east State of Chiapas, is one of the more recent victims of the heroin trade. Opium poppy cultivators, here as well as in the San Marcos department of nearby Guatemala and in the Huila and Tolima departments of Colombia, are indiscriminately removing thousands of hectares of high mountain forests at elevations of between 2,000 and 3,000 metres. Growers are commonly planting their crops on extremely fragile, well-watered, steep-sloped and narrow mountain canyons and in small isolated stream valleys, in order to limit their visibility. The recent shift of opium poppy cultivation to these new regions in Latin America is believed to be the result of successful government law enforcement and eradication programmes in the traditional growing regions of Mexico's northern States of Sinaloa, Durango and Chihuahua, among others.

Illicit cannabis cultivation

Cannabis cultivation and processing, unlike cocaine or heroin processing, generally do not include the use of toxic chemicals. Nevertheless, the impact of its cultivation upon forest environments in a number of countries has been no less profound. Growers of cannabis also plant their illicit crops on isolated mountain slopes disturbing fragile forest soils. Evidence of the tragic environmental consequences of rampant cannabis cultivation is particularly apparent in Colombia and Jamaica.

Colombia, until recently, was a major producer of illicit cannabis. Most of it was grown on the fertile slopes of the Sierra Nevada de Santa Marta and the Serrana de Perija mountains in north-east Colombia. The Santa Martas, which rise abruptly from the Caribbean to 6,000 metres in just 50 kilometres, have very steeply sloping, sharp-crested ridges that radiate outward from the central part of the mountain mass. The Perija range along the Venezuelan border to the east, although lower, has a similar topography. Initially, cannabis was planted in large fields carved out of these mountain forests and canyons at elevations from 1,000 to 2,000 metres. However, with the start of more effective law enforcement by the Colombian authorities in the mid - 1980s, growers moved to smaller plots located in much higher and more isolated mountain slope and canyon forests to plant their illicit crops.

There is no accurate assessment of the environmental aftermath of the excessive mountain deforestation by illicit cannabis growers in northern Colombia. Descriptive accounts by leading government and private organizations, including the National Police, the geological institute, environmental agencies and the Bogota press, cannot begin to depict the extensive and permanent nature of damage to these mountain environments by irresponsible narcotics organizations. Probably forfeited forever are the valuable forest resources and watershed, portions of national park reserves, and even indigenous lands. There are countless incidents of denuded mountain slopes and rock outcrops resulting from massive landslides and erosion. Related economic losses include the annihilation of large areas of the north coast shellfish industry, destroyed by heavy siltation from upland soil run-off, and productive lowland agriculture, victim of increased flooding and sedimentation.

Entrepreneurial Jamaican cannabis cultivators operate with an almost total disregard for the island's fragile tropical environment. Growers clear cut and destroy hilltop and steep-sloped hillside forests, exposing marginally fertile soils to rapid run-off and erosion. Additionally, after planting and harvesting as few as two or three crops, they abandon fields in favour of new forest soils. Inspection of cannabis regions of Jamaica reveals that the most permanently damaged forest environments are those of karst topography where thin limestone soils have left bare rock incapable of sustaining secondary growth. Moreover, damage from flooding in the central and western parishes in May and June 1986, described as some of the worst in the island's history, was largely attributed to unchecked upland deforestation. The Prime Minister of the country, in a nationally televised address, warned that continued downstream sedimentation from upland deforestation and soil erosion will have increasingly adverse effects upon the animal and plant life of the island's mangroves and coastal reefs.


Scientists have repeatedly warned of the dire consequences of tropical deforestation. By the same logic, the environmental damage from illicit narcotics cultivation and production will likewise produce landscape degradation and flooding, and be followed by declining agricultural and fishing productivity, and by malnutrition and disease. Humanity cannot afford the loss of species (genetic) diversity, increases in soil erosion and soil sterility, and the vast destruction of forests and watershed necessary to grow coca, opium poppy and cannabis. Moreover, the international community can no longer tolerate the relentless contamination of soils, water and air from poisonous chemicals used for the processing of narcotics, pesticides, and smoke from the burning down of forests. Whatever the costs, the benefits of curtailing the irreversible desecration of these fragile forest ecosystems are certainly greater.

In addition to the established programmes designed to decrease the supply and demand of illicit drugs, there is an immediate need for international bodies to undertake a multifunctional international approach in order to repress the continued wholesale destruction of large areas of the tropical environment by the cultivators and processors of illicit narcotics. Elements of the required programme might be based on the following recommendations:

  1. A strategy should be developed to warn the international community about the irreversible damage which the cultivation and production of illicit drugs is causing to the human and natural environment as a result of deforestation, degradation of natural resources and loss of economic productivity;

  2. An international intergovernmental campaign, with the participation of the United Nations family of organizations, national and international environmental and conservation organizations, and of the media, should be undertaken to foster public recognition and global awareness of the dire consequences of the environmental catastrophe caused by illicit narcotics cultivation and production;

  3. Government, academic, and private scientific research institutions and foundations should be encouraged systematically to monitor environmentally affected areas through remote sensing, aerial surveys and other resource evaluation technologies. Research on and assessments of forest resource loss and ecosystem contamination by dangerous products and wastes that have environmental and health implications should be advanced on an urgent basis;

  4. International financing institutions should be invited to join governments in order to expand narcotics control programmes such as crop substitution and alternative development;

  5. Eradication of illicit crops by all environmentally safe methods or techniques, including aerial spraying, should be actively promoted;

  6. Governments as well as interested public and private organiza- tions should identify areas, especially tropical forests, disturbed by illicit cultivation that may be suitable for reclamation, redevelopment or reforestation;

  7. Far-reaching efforts must be made to warn illicit cultivators, suppliers and consumers that drugs harm the environment as well as humans. Separate information campaigns, differently focused and constructed for each category of cultivators, suppliers and consumers, may be necessary;

  8. Political decision makers, administrators and financial donors to drug programmes should understand that their efforts are protecting the environment.


Barney, G. 0. The global 2000 report to the President of the United States. New York, Pergamon Press, 1980.

Brown, S. and A. E. Lugo. Tropical lands: popular misconceptions. Manzingira (Elmsford, N.Y.) S/2. 1981.

The Caribbean: why a 'trickle down' plan won't work. Christian Science monitor (Boston) 14 April 1982.

Clark, H. If a tree falls, John Seed hears it. Christian Science monitor (Boston) 13 August 1987.

Congress of the United States, Office of Technology Assessments. Technologies to sustain tropical forest resources. OTA-F-214, March 1984.

Development is eating up the world's rain forests. New York times, 31 August 1980.

Eckholm, E. Fatal disasters on the rise. New York times, 31 July 1984.

Farah, D. Cocaine chemicals foul Amazon Basin. Washington post, 20 November 1990.

Guppy, Nicholas. Tropical deforestation: a global view. Foreign affairs (New York) 1984.

Hamilton, L. S. Semantics, definitions and deforestation. TUCN bulletin (Honolulu)18:4-6, April-June 1987.

Humans' destruction of forests threatens species, report says. Los Angeles times, 7 June 1987.

Ilitis, H. H. What will be their fate? Tropical forests. Environment(Washington, D.C.) 25:10, December 1983.

Ives, J. D. Mountains' new challenge: how to save their ecology. Christian Science monitor (Boston) 28 April 1982.

Jacoby, T., M. Miller andR. Sandza. A choice of poisons. Newsweek(New York) 19 December 1988.

Lao People's Democratic Republic National Commission for Drug Control and Supervision. Drug control in 1990.

Lee, J. andR. Taylor. Ravage in the rain forests. U.S. news and world report (New York) 31 March 1986.

Lovejoy, T. E. Tropical deforestation and North American migrant birds. Bird conservation news and update. Madison, University of Wisconsin Press, 1983.

MacDougall, A. K. Man's dominant raw material. The vanishing forests. Need for wood forestalled conservation. LosAngeles times, 17 June 1987.

MacDougall, A. K. Solemn transition. Worldwide costs mount as trees fall Los Angeles times, 14 June 1987.

Petchsingh, T. Coffee flourishes in hills where opium poppies once bloomed. Reuters North European service (Chang Khian, Thailand) 5 November 1985.

Press, R. M. New techniques help save shrinking tropical forests. Christian Science monitor(Boston) 5 March 1981.

Proceedings of an international conference: "Assessment of drug control issues of controlled substance analogues". Rabat, Morocco, B- 11 September 1987. Co-sponsored by the World Health Organization and the Drug Enforcement Administration, United States of America.

Rain forest worth more if uncut, study says. Environment(Washington, D.C.), 4 July 1989.

Riding, A. In war on coca, U.S. weapon is bogged down in a dispute. New York times,28 June 1988.

Salati, E. andP. B. Vose. Depletion of tropical rain forests. Ambio(Brazil) 12:2:67- 71, 1983.

Shane, D. R. Hoofprints on the forest: cattle ranching and the destruction of LatinAmerica's tropical forests. Philadelphia, Institute for the Study of Human Issues, 1986.

Simon, J. L. Disappearing species, deforestation and data. New scientist (London) 15 May 1986.

Simons, M. Brazil parley aims to save rain forests. New York times, 28 June 1990.

The vanishing jungle. Economist (London) 4 September 1982.

Wiant, J. A. Narcotics in the Golden Triangle. Washington quarterly (Cambridge, Massachusetts) Fall 1985.

Williams, N. B., Jr. Rain forest and its medical secrets shrinking fast. Los Angeles times, 11 April 1988.