Wildemess and Environmental Medicine, 6,452-456 (1995)

Letter to the editorsBio~iversityand human health

To the Editors:

In April 1995 Peter Hackett and I had the pleasure of attending a conference inWashington DC entitled "Biodiversity and Human Health" held at the SmithsonianInstitute. It was a 2-day meeting to explore the human health consequences of loss ofbiological diversity associated with environmental degradation, excessive resource exploi­tation, and mounting population pressure. Biodiversity loss alters the epidemiology ofhuman diseases, diminishes the supplies of raw materials for drug discovery and biotech­nology, and threatens food production and water quality. The purpose of the conferencewas to open a dialogue on these issues between experts on the global environment andfrom the biomedical professions.

It was sponsored by the National Institutes of Health (NIH), the National ScienceFoundation (NSF), the Smithsonian, and the National Association of Physicians for theEnvironment (NAPE). There were 32 speakers, including 6 physicians. The majority werescientists in ecology, evolutionary biology, botany and ethnobotany, virology, conservationbiology, primatology, pharmacology and toxicology, and zoology. A wonderfully diversegroup of organizations were represented, including government (in addition to thesponsoring agencies, also present was the American Museum of Natural History), ahalf-dozen universities, various conservation organizations [including Population ActionInternational, Conservation International, and the Biodiversity Support Program, a UnitedStates Agency for International Development (USAID) funded consortium effort of theNature Conservancy, the World Wildlife Fund, and the World Resources Institute], thepharmaceutical industry, physician groups [including the American Medical Association,the Office of Alternative Medicine, and the National Cancer Institute (NCI) at the NIH,Physicians for Social Responsibility, and of course us, the Wilderness Medical Society(WMS)], and assorted other interested groups such as the New York Botanical Gardenand the Center for International Environmental Law. This stimulating and adventurousgroup of scientists and physicians communicated an unexpected vision of hope. For severalyears now they have embraced environmental studies in their professional lives and arenow coming together in recognition of the "and" in the conference subject "biodiversityand human health."

Several organizing themes emerged during the conference. First, Dr. Tom Lovejoy, atropical and conservation biologist who is currently the Assistant Secretary for ExternalAffairs at the Smithsonian Institute and is the founder of the PBS series "Nature," spoketo a vision of the future. He perceives that we are moving toward the "century of biology,"including biotechnology (genetic engineering), bioengineering (i.e., adapting biologicalknowledge to accomplish processes previously performed chemically), bioremediation(clean-up), and nanotechnology (i.e., at the level of the molecule). The basic foundationfor all of these is biodiversity, which must be preserved in order for the rest to be successfuland progressive.

The need to preserve biodiversity is unequivocal if one considers environmental ethics

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and maintains a hopeful vision of a sustainable future. Most of earth's biodiversity isclustered in tropical regions. These "hot spots" of diversity occur in Africa, Central andSouth America, and tropical Asia, areas populated by humanity for thousands of years.These indigenous peoples are integrally intertwined with their habitat, and they are thekeepers of the cumulative knowledge of generations who have used their environment forfood, shelter, medicines, and as part of their spiritual/cultural traditions. The preservationof these cultures is an integral part of the preservation of the biota. Traditional healers/shamans hold much of the cultural knowledge of medicinal plants, which possess as yetunknown activity against human disease. Other pharmacologically active compounds (e.g.,obtained from insects, fungi, and bacteria) are potentially also useful in agriculture (e.g.,activity in plant resistance to pests and disease), and other forest products can be used fornovel food production.

The shamans are growing old and their knowledge is dying out, as is their culture. Thewesternization of their culture, the loss of habitat due to deforestation (often due toplanting crops grown for export to the world market to reduce their nations foreign debtburden), and population pressure are all pivotal factors in the accelerating loss ofbiocultural diversity. Fortunately, a growing number of ethnobotanists, pharmaceuticalcompanies, conservation organizations, and governmental agencies recognize this crisisand are actively engaged in efforts to support local villages in the sustainable harvesting ofrainforest products, preserving the shamanistic tradition, and funneling funds arising fromproducts obtained from the rainforest back in the local economy.

Protection of indigenous peoples' financial interests and their intellectual propertyrights is imperative, if biodiversity is to be preserved. Dr. Paul Cox, an ethnobotanist atBrigham Young University, gave an impassioned talk on these issues and the work he hasbeen doing in Polynesia since the late 1980s, assisting Somoan islanders in establishing anational park protecting rainforest and reef. In collaboration with drug companies and theNCI, they are developing potentially medically active compounds, including an antiviralagent with anti-HIV-l activity. Dr. Thomas Mays described the NCI's "Letter of Collec­tion" as "a contractual agreement that permits the recognition and financial reward ofindigenous peoples and source countries for the contribution to the identification andcollection of natural products with potential therapeutic value in the treatment of cancerand AIDS."

There were several presentations on "bioprospecting," a term used to describe thecollection and analysis of "samples of biodiversity" with the goal of finding natural sourcesof raw materials for new products such as medicines, crop varieties, foods, and biotechnol­ogy products. Seventy-five percent of the 150 most commonly prescribed drugs are"natural" or naturally derived, including Zantac, Xanax, Vasotec, and Premarin. Tech­niques for discovery include an ethnobotanical approach, random sample collection, and a"biorational" approach (i.e., further exploration of plants already known to make bioac­tive compounds, and related plants), or investigating suggestive ecological relationships(e.g., insects which eat toxic plants must have chemicals to detoxify).

Dr. Joshua Rosenthal, an ethnobotanist and ecologist at the Fogarty InternationalCenter at the NIH, described the International Cooperative Biodiversity Groups Program,which integrates the processes of drug discovery from natural products, conservation ofbiodiversity, and sustainable economic development. It is supported by the NIH, the NSF,and USAID. Other interesting projects in marine and rainforest bioprospecting weredescribed. Compounds are being developed from fungal and bacterial origins also. A plea

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from Nobel Prize Winner Dr. Joshua Lederberg, a molecular geneticist at the RockefellerUniversity, advocated the merits of microbiological diversity preservation. The logistics ofpharmaceutical research and development, the expense of getting a drug to market, andpublic and governmental policy issues were discussed.

Dr. Charles Peters, a plant ecologist at the New York Botanical Garden, encouraged usto question the myth that sustainable development through bioprospecting, specifically ofnontimber tropical forest products (NTFP) such as fruits, nuts oil seeds, latexes, andmedicinal plants, has no ecological impact on a tropical forest. Rainforests are character­ized by high species diversity but often low numbers of individuals of a given species.Sustainability requires the reproduction of each and every species which make up acomplex web of interconnected relationships. This includes, for example, pollinators likeinsects, which may be drastically affected by NTFP harvesting. Although NTFP harvestingmay thus visually appear to have no impact (i.e., big trees are still standing), actuallylong-term viability is being dramatically affected. These ecological relationships are largelyunknown but must be understood in detail for sustainable collection to truly occur.

What are the implications for human health of biodiversity loss? Dr. Andy Dobson, anecologist and evolutionary biologist at Princeton University, gave a thought-provoking talkon emerging diseases, making several points. First, pathogens can more readily establish inlarge populations, particularly when they are aggregated into large urban centers. As thehuman population continues to increase, newly emergent pathogens will find it progres­sively easier to establish. Next, land degradation from logging, overgrazing, burning, and soforth, results in an explosion of other organisms like ticks, fleas, and chiggers. Thesecreatures become vectors for pathogens, providing a source of infection which can lead toimportant human epidemics. Lyme disease is an example of this process. Forests werecleared in the 1700-1800s in the northeastern United States to make way for agriculture,eliminating deer and their predators. The forests and deer eventually returned, but not thepredators. The deer tick was able to spread unimpeded. At the same time, many morepeople moved into the area, greater numbers of people were bitten by infected ticks (whichhad acquired the infection from local rodents), and the Lyme disease epidemic was born.Human contact with degraded habitats is also important in yellow fever. Humans serve ashosts for the pathogen mainly when forests are being cleared, bringing people into contactwith the mosquitoes that normally live in the forest canopy along with the monkeyreservoir.

Dr. Eric Chivian, a physician and founding member of Physicians for Social Responsibil­ity and editor of the book Critical Condition: Human Health and the Environment (anexcellent resource book which comprehensively reviews the medical consequences ofenvironmental degradation), addressed these issues further. Human activity can alterbiological diversity via many mechanisms, including habitat destruction, global climatechange, ozone depletion, and toxic pollution of ecosystems. The study of "indicatorspecies" (i.e., those especially sensitive to environmental changes) and their surroundingecosystems thus provide an early warning and may be the best method for following dangersignals to human health and life. Climatic change also creates a loss of equilibriumbetween predator and prey species, which changes infectious disease patterns, sometimesleading to catastrophic consequences for humans. An example of this is the recenthantavirus outbreak in the southwestern United States. A 6-year drought in the area hadeliminated most of the predators of the deer and mice which are carriers of hantavirus.When heavy rains produced an abundance of nuts and grasshoppers, the mice flourished.

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People came into contact with the mice and their droppings, acquiring the disease.Interestingly, the epidemiology of this outbreak was elucidated rather quickly becauseecologists have been studying this area for the past several years, lending further credibilityto the notion that ecology, biodiversity, and human health are linked in myriad ways. Dr.Chivian also spoke about invaluable medical models "out there" to be studied, which mayoffer clues for understanding human physiology and disease. Examples include dart­poison frogs who employ sodium-potassium channel poisons, which may be the source ofnew pharmacologic agents, sharks who rarely develop tumors because of a substance whichinhibits growth of new blood toward solid tissue, and denning bears who do not suffer boneloss which could have implications for osteoporosis.

Dr. Theo Colburn, a zoologist and toxicologist with the World Wildlife Fund, gave acompelling discussion on transgenerational loss of function. Many synthetic chemicalsaccumulating in the environment, including PCBs and insecticides, chemically look likeand/or interfere with signals from naturally occurring neurotransmitters, hormones,growth factors, and inhibiting substances. Although these chemicals are present in too lowa concentration to affect children or adults, they are transmitted across the placenta andlikely can exert toxic effects on the developing fetus. Generally, these effects are notmanifested as obvious structural birth defects but as a loss of endocrine, reproductive, orneurologic function later in life. For example, many of these chemicals bind testosteronereceptors exerting an antiandrogen effect. A neuterizing of offspring in alligators exposedto these chemicals has been reported. In humans, sperm counts have been declining 2%per year since the 1970s, along with decreased motility and quality of sperm. Perhaps this isa result of a toxic effect of these chemicals on human embryologic development which ismanifested later during reproductive years.

A synthesizing sociopolitical world view and outline for collaboration between thebiomedical and conservation communities was cogently offered by Dr. Walter Reid, anecologist at the World Resources Institute (a policy research institute "focusing on thenexus of environmental and economic development issues of international importance").He described the industrial revolution as insulating society from the direct environmentaland economic costs of the degradation of biodiversity. The green revolution shifted costsof mismanaged agricultural biodiversity onto future generations. The health care revolu­tion has seemed once and for all to place health security in our own hands, insulating usfrom our unpredictable environment. His hope is that public health concerns can helprestore the idea that sound management of the world's biodiversity is an important societalgoal. In his view, the most promising opportunities for collaboration include examinationof the potential indirect impacts of climate change on public health (e.g., EI Nino's role inthe recent cholera outbreak in South America), enhancing traditional medical care andintegrating traditional medicines into public health care systems (80% of the world'spopulation uses traditional medicine as their primary health care), using an ecologicalapproach to search for new pharmaceutical products, and joint public awareness effortsthat demonstrate the ties between public and environmental health.

What then must we do? As it is apparent that the conservation of biodiversity is a salientissue for only a small minority of people and that society will not act to preserve otherspecies "for their own sake," people must be informed about the implications for humanhealth from biodiversity loss. Hopefully, this will motivate us to act. Dr. Byron Bailey,chairman of the Committee on Biodiversity of NAPE, spoke of the mission of NAPE:public education on the merits of protecting biodiversity; supporting research which links

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environmental health and human health; developing a physician network active inexplaining ecological concepts to patients; and forming effective alliances with othersinterested in biodiversity to form a "synergistic linkage." To this end, Dr. John Grupen­hoff, the Executive Director of NAPE, proposed forming a "National Council of Scienceand Medicine for the Protection of Biological Diversity." The council's first meeting washeld at the end of the Washington DC meeting, attended by several of the speakers andother conference participants, including Peter and myself. It is currently in evolution andpromises to be an exciting forum of scientists and health care providers, coordinating ourefforts in research and education regarding biodiversity and human health.

Future conferences are already being planned such as the International Congress onAlternative Medicine in La Paz, Bolivia, November 19-25, 1995, focusing on ethnobotani­cals; the International Society of Doctors for the Environment Assembly was just held inBrazil, August 10-12, 1995. Another project that might interest WMS members is EarthIsland Institute's "Muktinath Medicinal Plant Conservation Project." The goal of thisproject is to protect and conserve medicinal plants in this region of Nepal, in partnershipwith local residents and the Muktinath Traditional Tibetan Medical Center. I would like toinvite anyone with questions, comments, or interest in any of the above to contact me viathe WMS office.

KiMBERLY JOHNSON MDDurango, Colorado, USA

Chairperson, Environmental CouncilWilderness Medical Society