Human Health Threat From
Ecosystem Degradation

Threats particularly acute in poorer countries 

Press Release / WHO 9dec2005

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BANGKOK and GENEVA — The World Health Organization (WHO) is publishing a report, Ecosystems and Human Well-being: Health Synthesis, which represents an attempt to describe 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. But not all regions and groups of people have benefited equally from this process."

Approximately 60% of the benefits that the global ecosystem provides to support life on Earth (such as fresh water, clean air and a relatively stable climate) are being degraded or used unsustainably. In the report, scientists warn that harmful consequences of this degradation to human health are already being felt and could grow significantly worse over the next 50 years.

"The benefits should be acknowledged," said Dr Carlos Corvalan, WHO's lead expert 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."

Ecosystem services are absolutely vital to preventing disease and sustaining good health, the Health Synthesis report underlines. Many important 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. For example, the Nipah virus is believed to have emerged after forest clearance fires in Indonesia drove carrier bats to neighbouring Malaysia, where the virus infected intensively-farmed pigs, and then crossed to humans.

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 notes. 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.

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

• Nutrition: Degradation of fisheries and agro-ecosystems are factors in the malnutrition of some 800 million people around the world. At least an additional billion people experience chronic micronutrient deficiency.

• Safe Drinking-Water: Water-associated infectious diseases claim 3.2 million lives, approximately 6% of all deaths globally. Over 1 billion people lack access to safe water supplies, while 2.6 billion lack adequate sanitation, and related problems of water scarcity are increasing, partly due to ecosystem depletion and contamination.

• Solid Fuel Dependency: About 3% 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.

"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. "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."

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 well-being, past, present and future.

For Technical Information contact Dr Carlos Corvalan, Coordinator and Scientific Expert, World Health Organization, Geneva, Tel: (+41 79) 445 1624 . Email corvalanc@who.int and Dr Diarmid Campbell-Lendrum, Scientist, World Health Organization, Geneva, Tel: (+41 22) 791 4261. Email: campbelllendrumd@who.int

For Media Information contact Ms Nada Osseiran, Technical Officer, Advocacy & Communication, Health and Environment, WHO, Geneva, Tel in Bangkok as from ₇th December: Mobile 01 921 5609 or 02-984-8620 to 34. Fax: 02-984- 8665. Email: osseirann@who.int

All WHO Press Releases, Fact Sheets and Features as well as other information can be obtained on Internet on the WHO home page: http://www.who.int/

Ecosystems and Human Well-Being: Health Synthesis can be found on: http://www.who.int/globalchange. Other Millennium Ecosystem Assessment reports can be found on: http://www.maweb.org

source: http://www.who.int/entity/globalchange/ecosystems/ecosyspressrelease.pdf 11dec2005

Ecosystems and Human Health:
Some findings from the Millennium Ecosystem Assessment

Why do ecosystems matter to human health?

In a very fundamental sense, ecosystems are the planet’s life-support systems - for the human species and for all other forms of life. The needs of human biology for food, water, clean air, shelter and relative climatic constancy are basic and unalterable.

Ecosystem services are indispensable to the wellbeing of all people, everywhere in the world. The causal links between environmental change and human health are complex because they are often indirect, displaced in space and time, and dependent on a number of modifying forces (Figure 1).

Figure 1. Interrelationship between ecosystem services, aspects of human well-being and human health

Food

In poor countries, especially in rural areas, the health of human populations is highly dependent upon the services of local productive ecosystems for food. Aggregate food production is currently sufficient to meet the needs of all, yet of the present world population of just over 6 billion, about 800 million are underfed with protein and/or energy, while a similar number are overfed. At least an additional billion people experience chronic micronutrient deficiency. In richer urban communities human dependence on ecosystems for nourishment is less apparent, but ultimately no less fundamental. aspects of human well-being and human health.

Fresh water

Over 1 billion people lack access to safe water supplies, while 2.6 billion people lack adequate sanitation. This has led to widespread microbial contamination of drinking water. Water-associated infectious diseases claim up to 3.2 million lives each year, approximately 6% of all deaths globally. The burden of disease from inadequate water, sanitation, and hygiene totals 1.8 million deaths and the loss of greater than 75 million healthy life years. It is well established that investments in safe drinking water and improved sanitation show a close correspondence with improvement in human health and economic productivity. Each person needs 20 to 50 liters of water free of harmful chemical and microbial contaminants each day for drinking and hygiene. There remain substantial challenges to providing this basic service to large segments of the human population.

Fuel

The generation of power causes a range of health impacts. Outdoor air pollution aggravates heart and lung disease. Indoor air pollution, most typically from the combustion of biofuel in poorly ventilated heating and cooking environments causes a major burden of respiratory diseases amongst adults and children. About 3% of the global burden of disease has been attributed to indoor air pollution from this source. In areas where the demand for wood has surpassed local supply, and where people cannot afford other forms of power, there is increased vulnerability to illness and malnutrition from consuming microbiologically- contaminated water, from exposure to cold, and from a lack of properly cooked food. Poor women and children in rural communities are often the most affected by wood fuel scarcity. Many must walk long distances searching and carrying firewood (and often, water) and therefore have less time and energy for tending crops, cooking meals or attending school. For these reasons, adequate energy supplies are fundamental for sustainable development.

Nutrient and waste management, processing and detoxification

Humans are at risk from inorganic chemicals and from persistent organic pollutants in food and water. This can occur both when attempts to access water resources leads to contamination from natural sources (as occurred with arsenic contamination of water in tubewells in Bangladesh), and where human actions result in release of toxic chemicals into the environment (for example through use of pesticides). Toxic chemicals can cause a variety of adverse health effects in various organ systems. Some chemicals present in industrial effluent or used as pesticides, such as PCBs, dioxins and DDT, may act at low exposure levels as “endocrine disrupters” which interfere with normal human physiology, undermining disease resistance and reproduction.

Cultural, spiritual and recreational services from ecosystems

Cultural services may be less tangible than material services, but are nonetheless highly valued by people in all societies. People obtain diverse non-material benefits from ecosystems. They include recreational facilities and tourism, aesthetic appreciation, inspiration, a sense of place and educational value. There are traditional practices linked to ecosystem services that have an important role in developing social capital and enhancing social well being.

Climate regulation

Each of the ecosystem services referred to in the previous sections is sensitive to climate, and will therefore be affected by anthropogenic climate change. Although climate change will have some beneficial effects on human health, most effects are expected to be negative. Direct effects such as increased mortality from heat waves are most readily predicted, but indirect effects are likely to have a greater overall impact. Human health is likely to be impacted indirectly by climate-induced changes in the distribution of productive ecosystems, and the availability of food, water and energy supplies. These changes will in turn affect the distribution of infectious diseases, nutritional status and patterns of human settlement.

What actions are required to address the consequences of ecosystem change for health?

There are two routes to avoiding disease and injury caused by ecosystem disruption. One is to prevent, limit or manage environmental damage; the other way is to make whatever changes will protect individuals and populations from the consequences of ecosystem change. Two aspects need to be considered to understand the potential negative health impacts of ecosystem change: the current (and likely future) vulnerability of populations and their future capacity for adaptation. These two aspects are closely related. The forces that place populations at risk (such as poverty and high burdens of disease) in many cases also impair the capacity of these populations to prepare for the future.

What are the policy implications of the threats that ecosystem change present to health?

Measures to ensure ecological sustainability would safeguard ecosystem services and therefore benefit health in the long-term. Where a population is weighed down by disease related to poverty and lack of ‘entitlement’ — culturally or socially determined right of access to essential resources such as shelter, nutritious food or clean water — the provision of these resources should be the first priority for public health policy. Where ill-health is caused, directly or indirectly, by excessive consumption of ecosystem services (such as food and energy) substantial reductions in consumption would have major health benefits while simultaneously reducing pressure on life-support systems.

The ongoing degradation of ecosystem services is a significant barrier to achieving the Millennium Development Goals. Ecologically unsustainable use of ecosystem services raises the potential for serious and irreversible ecological change. Ecosystem changes may occur on such a large scale as to have a catastrophic effect upon the economic, social and political processes upon which social stability, human wellbeing and good health are dependent. This suggests that a precautionary approach to environmental protection is most likely to protect and enhance health. Unavoidable uncertainties about the impacts of global environmental changes on public health should not be an excuse for delaying policy decisions.

source: http://www.who.int/globalchange/ecosystems/ecosys05sum.pdf 11dec2005