World Health Body Links Ecosystem Injury to Human Health Problems

GENEVA, Switzerland, December 9, 2005 (ENS) - Sixty percent of the benefits that the global ecosystem provides to support life on Earth - fresh water, clean air, abundant wildlife and a relatively stable climate - are being degraded or used unsustainably with negative effects on human health, finds a new report released today by the World Health Organization (WHO).

"Ecosystems and Human Well-being: Health Synthesis," explores the complex links between the preservation of healthy and biodiverse natural ecosystems and human health.

"Over the past 50 years, humans have changed natural ecosystems more rapidly and extensively than in any comparable period in human history," said Dr. Lee Jong-wook, director-general of the World Health Organization.

"This transformation of the planet has contributed to substantial net gains in health, well-being and economic development," said Dr. Lee, adding that not all regions and groups of people have benefited equally from this process.

In the report, scientists warn that harmful consequences of ecosystem degradation to human health are already being felt and could grow worse over the next 50 years.


Dr. Carlos Corvalan is an assistant professor in the Department of Agricultural and Biological Engineering at Indiana's Purdue University. (Photo courtesy Purdue)
"The benefits should be acknowledged," said Dr. Carlos Corvalan of Purdue University, WHO's lead author on the report. "But these benefits are not enjoyed equally. And the risks we face now from ecosystem degradation, particularly among poor populations directly dependent on natural ecosystems for many basic needs, has to be addressed."

The Health Synthesis Report is WHO's contribution to the broader Millennium Ecosystem Assessment, a four year series of studies and reports, involving over 1,300 scientists, considering impacts on human wellbeing, past, present and future.

Ecosystem services are absolutely vital to preventing disease and sustaining good health, the Health Synthesis report emphasizes.

"Nature's goods and services are the ultimate foundations of life and health, even though in modern societies this fundamental dependency may be indirect, displaced in space and time, and therefore poorly recognized," writes Dr. Lee in his Forward to the report.

Many serious human diseases have originated in animals, and so changes in the habitats of animal populations that are disease vectors or reservoirs, may affect human health, sometimes positively and sometimes negatively, the report explains.

Sometimes the environmental circumstances leading to disease transmission are complex. For example, the Nipah virus is believed to have emerged after forest clearance fires in Indonesia drove carrier bats to neighboring Malaysia, where the virus infected intensively farmed pigs, and then crossed to humans.

bush meat

Young African man carries bush meat he has taken from the forest. Eating wild animal meat exposes people to a variety of pathogens. (Photo courtesy Wildlife Foundation)
Intensive livestock production, while providing benefits to health in terms of improved nutrition, has also created environments favorable to the emergence of diseases, the report points out.

Increased human contact with wild species and "bush meat" as a result of encroachment in forests and changes in diet also create opportunities for disease transmission.

Trends ranging from forest clearance to climate-induced habitat changes also appear to have impacted certain populations of mosquitoes, ticks and midges, altering transmission patterns for diseases like malaria and Lyme disease.

Deforestation also endangers health by intensifying the effects of natural disasters such as floods and landslides, resulting in reduced crop yields. This impairs the nutritional status of households and diet deficiencies harm children's physical and mental development. In turn, this can impair the livelihoods of farmers and limit the options open to their children.

Pressures on ecosystems could have unpredictable and potentially severe future impacts on health, the report states. Regions facing the greatest risks include sub-Saharan Africa, Central Asia, parts of Latin America, and certain areas in South and Southeast Asia.

Harm to ecosystems needed for human nutrition and safe drinking water as well as dependence on solid fuels such as wood and charcoal are viewed as some of the most serious problem areas.

Degradation of fisheries and agro-ecosystems are factors in the malnutrition of some 800 million people around the world, the WHO report finds, echoing the findings of many other reports from United Nations and nongovernmental organizations. At least an additional billion people experience chronic micronutrient deficiency.

Infectious waterborne diseases claim 3.2 million lives, approximately six percent of all deaths globally. Over one billion people lack access to safe water supplies, the report finds, while 2.6 billion lack adequate sanitation.

Related problems of water scarcity are increasing, partly due to ecosystem depletion and contamination, WHO warns in the report.


After cutting down the trees, charcoal production is the next step in conversion of the Amazon rainforest to cattle ranching. Here a charcoal burner's hut in the Brazilian state of Amazonia produces solid cooking fuel. Burning it can lead to respiratory problems. (Photo by Rogerio Mauricio courtesy FAO)
About three percent of the global burden of disease has been attributed to indoor air pollution, a major cause of respiratory diseases. Most of the world's population uses solid fuels to cook and heat, a factor in deforestation as well as indoor air pollution.

On the other hand, health benefits are derived from having a full complement of species, intact watersheds, climate regulation and genetic diversity, the authors say. Stresses on freshwater sources, food-producing systems and climate regulation could cause major adverse health impacts.

"Human health is strongly linked to the health of ecosystems, which meet many of our most critical needs," said Maria Neira, director of WHO's Department for the Protection of the Human Environment.

Neira says the report is a wake-up call for healthcare professions around the world. "We in the health sector need to take heed of this in our own planning, and together with other sectors, ensure that we obtain the greatest benefit from ecosystems for good health now and in the future."