The maintenance and improvement of health should be at the centre of concern about the environment and development. Yet health rarely receives high priority in environmental policies and development plans, rarely figures as an important item in environmental or development programmes, despite the fact that the quality of the environment and the nature of development are major determinants of health
Indeed, the most immediate problems in the world are ill health and premature death caused by biological agents in the human environment in water, food, air, and soil. They contribute to the premature death of millions of people, mostly infants and children, and to the ill health or disability of hundreds of millions more. The problem is most acute in the developing countries where:
-- four million infants or children die every year from diarrhoeal diseases, largely as a result of contaminated food or water;
-- over a million people die from malaria each year and 267 million are infected
-- hundreds of millions suffer from debilitating intestinal parasitic infestations
Serious environmental health problems are shared by both developed and developing countries, affecting:
-- hundreds of millions of people who suffer from respiratory and other diseases caused or exacerbated by biological and chemical agents, including tobacco smoke, in the air, both indoors and outdoors;
-- hundreds of millions who are exposed to unnecessary chemical and physical hazards in their home, workplace, or wider environment (including 500 000 who die and tens of millions more who are injured in road accidents each year)
Health also depends on whether people can obtain food, water, and shelter. Over 1000 million people lack the income or land to meet such basic needs. Hundreds of millions suffer from undernutrition.
It is a requirement of health that the global cycles and systems on which all life depends are sustained. Population growth and the way resources are exploited and wastes generated threaten the environmental base on which health and survival depend and transmit the growing costs to future generations. The toll they exact on human health and natural resources and systems could be enormously reduced by better environmental management.
Health depends on our ability to understand and manage the interaction between human activities and the physical and biological environment. We have the knowledge for this but have failed to act on it, although we have the resources to meet current and future needs sustainably.
Two concerns are vital: development addressing people's needs, especially for health; and ecological sustainability so that natural resources are not depleted and natural systems not damaged or degraded. Meeting the needs of the present and future world population for food, water, and energy without depleting or damaging the global resource base, while avoiding the adverse health and environmental consequences of industrialization and uncontrolled urbanization, can be achieved only if people have the knowledge and the means to influence action. This calls for changes in the way governments plan and manage development. In agriculture, research and extension services are required that are more participatory and more responsive to the needs of poor farmers. In urban areas participatory partnerships between local authorities and community organizations need to be developed. People dependent on natural resources should be fully involved in decisions about their use and protection. All groups, including those who are living and working in the least healthy environments or are currently excluded from decisions about how resources should be used, should share in decision-making and action.
Local participation needs national and global frameworks to ensure that adequate knowledge and resources are available and that local actions do not result in an unsustainable burden on natural cycles and systems. It also requires intergovernmental agreements that limit each country's call on finite resources and its right to dispose at will of non-biodegradable wastes. For this, people are needed whose concerns go beyond the quality of their own environment; only they can press their governments to reach the international consensus on which a healthy and sustainable planet depends.
Any discussion of health, the environment, and development must include consideration of the size of the population and its consumption level, since this combination largely determines the impact that the human population makes on the environment. It must include the distribution of income and assets, the prime concern being for people whose health is impaired by lack of them. It must also include the macroeconomic framework within which governments set their economic, social, and environmental policies. While the priority is to change the sectoral policies of governments and international agencies so as to promote health and sustainability, macroeconomic policies affect all sectoral policies.
The world's population grew more than fivefold between 1800 and 1990 to reach over 5000 million; projections suggest 8000 million by 2020. In developing countries, where populations are still expanding, pressure on scarce resources has made it difficult to improve living conditions; in the towns and cities the authorities have rarely been able to provide the extra services required by the rapid growth in population. In developed countries, where population levels are largely static, prosperity has given rise to increased consumption and even overconsumption with insufficient regard being paid to their possible planetary impact the depletion of non-renewable resources, the degradation of soil and water resources, and the emission of gases that threaten climatic stability and the stratospheric ozone layer. Such consumption levels raise the question of sustainability, especially as a growing proportion of the world's population aspires to comparable levels of consumption.
Healthier environments and lower death rates are not inconsistent with the goal of reducing population growth rates. Indeed, the steps that reduce infant and child deaths also tend to encourage reduced fertility rates a secure livelihood, better health and education of the mothers, improved water supplies, sanitation, and nutrition, all coupled with effective family planning programmes integrated into health care systems available to all. Where serious measures are taken for a sustained reduction in child mortality, the fertility rates eventually fall. Sustaining reductions in fertility requires policies that remove the economic necessity for poorer groups to have large families. But the pressure on resources of growing populations and growing consumption levels is so severe that to wait for economic expansion to reduce fertility would be disastrous. Provision of a secure livelihood, education, and health care (including the means to control fertility) is therefore a high priority.
At least 1115 million people were classified as poor in 1985 and 630 million of these were living in extreme poverty such statistics cover only those with an inadequate income. The number lacking a minimum standard of living is much higher. Those who cannot read, obtain clean water, or avoid environmentally induced disease, and who are permanently under the threat of physical violence and the effects of crime are invariably poor, whatever their income. So too are those who cannot participate in community life or expect to live beyond the age of 60. If poverty is measured by the number of people lacking a standard of living that includes adequate food, safe and sufficient water, sanitation, a secure shelter, and access to education and health care, over 2000 million people live in poverty--some 40% of the world's population. A high proportion are women and children, who are more vulnerable to environmental health risks. Within households it is generally women who look after the children, manage the household, and care for the sick; as such they suffer more from the diseases associated with inadequate water and sanitation and from the defects in the provision of basic services. Women who head households also usually face discrimination in looking for jobs and in obtaining access to public services, housing, and credit.
The impact of any population on the environment depends on the type and level of its resource use and on its waste generation and management. Most of the world's consumption of non-renewable resources is concentrated in Europe, North America, and Japan. Per caput consumption levels in the richest countries are 50 or more times higher than in the poorest countries. The OECD nations, with 15% of the world's population, are responsible for 77% of all hazardous industrial waste. More than 80% of the gases in the atmosphere that contribute to the greenhouse effect arise from production or consumption in the developed world.
A healthy population may require a relatively prosperous and stable economy, but this need not imply the levels of income and resource consumption common in developed countries. Many communities with a relatively low level of income have made substantial improvements in health; some have achieved a life expectancy close to that of West Europe and North America with a much lower level of resource use. Improved health can be separated from ever-increasing consumption if development programmes stress the promotion of health both in the narrow sense of curing or preventing disease and in the broad sense of promoting well-being and informed participation.
Macroeconomic policies are major influences on the state of health and of the environment within all countries. But they are usually established with little or no consideration given to their health or environmental consequences. For example, trade and fiscal policy or agricultural or energy pricing may influence health either by their effect on income levels and distribution or by the effect on the quantity and quality of land, air, and water resources. Macroeconomic policies influence the extent to which health care and health-related services are funded. They also affect the size of household incomes, and hence the quality of food and housing affordable.
Macroeconomic policies should minimize conflicts between economic, environmental, and health goals. With increased knowledge of the social and environmental effects of macroeconomic policies the effects can be limited, including those which arise from structural adjustment, and special programmes can be established for those whose health might otherwise suffer from loss of income or cuts in services--for instance health care or nutrition programmes or employment projects.
Agriculture, forestry and fishing provide not only the food and natural resources on which human society depends but also the livelihood of about half of the world's population. Their output can only be sustained if the ecological systems on which they draw are not overexploited.
The output of the world's food-producing systems has greatly increased over the past few decades. As yet there is no global shortage of food or the capacity to produce it in the world, but for a large part of the world's population undernutrition and the infections associated with it will remain the main cause of ill health and premature death because they do not have enough land to grow the food they need or the income to purchase it. Foodborne diseases are among the most common diseases in every country, although they are far less often life-threatening in developed countries. Most disease agents that contaminate food and water are biological and come from human or animal excreta, although food contaminated by toxins produced by plants and moulds, and those present in fish and shellfish, can be a serious problem.
The ecological base for feeding the world's population is under stress owing to the rapid degradation or land and water resources. Production and distribution methods remain inefficient, as is shown by the size of the losses before and after harvesting. A continued rise in the population in a number of developing countries, greater substitution of meat, eggs and dairy products for grains and vegetables, and increased food and soil losses put great stress on farmers and on the ecological underpinnings of farming systems. Conversely, reduced population growth, better-balanced diets, changes in production techniques, and greater attention to reducing food losses would make it possible for farmers to sustain production and meet future demands.
Agriculture is not without occupational health risks, of which accidents, infection with diseases spread by animals, and exposure to agricultural chemicals are the most common. In tropical countries, water reservoirs and canals for irrigation have been constructed and new land opened up for agricultural use without proper control of disease vectors. The result is that they have often been followed by a great increase in many of the most lethal and debilitating diseases, including malaria and schistosomiasis.
Agricultural chemicals are widely misused, most seriously in developing countries where pesticide regulations and their enforcement are less strict and products that have been banned or restricted in developed countries are still widely available. Agricultural chemicals are damaging water resources. Drainage water often contains high levels of salts and nutrients, the latter causing blooms of algae in lakes, reservoirs, and shallow coastal waters.
Health and its environmental determinants are closely related to land tenure. Farmers with secure tenure of adequate amounts of fertile land usually avoid extreme poverty and the ill health that accompanies it. Those with little security and too little land or holdings of only marginal productivity are often poor; so is their health. Many small farmers have developed a sophisticated knowledge of how to sustain yields in difficult circumstances. However, environmental degradation is common where high concentrations of poor farmers have only land of poor quality to exploit.
Certain strategic principles can promote health and more sustainable patterns of food production. They include the promotion of good agricultural practice (for instance, crop rotation, avoidance of excessive fertilizer application, use of correct dosage of chemicals or pesticides, reduction of food losses before and after harvesting). They also include wider use of integrated pest control and better integration of farming, forestry, and water resource management. Several major innovations are likely to prove of particular importance for increased food production or better preservation; they include food irradiation and the use of modern biotechnology to improve productivity and processing.
The Commission recommended that:
Fresh water is considered a renewable source, but there are limits on the supplies available. In many countries or regions, shortages of fresh water are the main obstacle to agricultural and industrial production. Some of the shortages (or seasonal or annual variations in supplies) lead to poverty and soil degradation. Many cities and agricultural regions are now drawing supplies from underground aquifers at a rate far above their natural rate of recharge.
Fresh water is essential to health not only for its part in production but also for domestic consumption and use (drinking, cooking, washing, laundry). A high proportion of life-threatening and health-threatening infections are transmitted through contaminated water or food. Nearly half the world's population suffer from diseases associated with insufficient or contaminated water, mostly the poor and virtually all in developing countries. Two thousand million people are at risk from waterborne and foodborne diarrhoeal diseases, which are the main cause of nearly four million child deaths each year. Schistosomiasis (200 million people infected through contact with infested fresh water) and dracunculiasis (10 million infected through drinking water containing the disease vector) are two water-based diseases. Insect vectors breeding in water transmit malaria (267 million infected), filariasis (90 million infected), onchocerciasis (18 million infected), and dengue fever (30-60 million infected every year).
Water shortages usually lead to problems of water quality since sewage, industrial effluents, and agricultural and urban run-off overload the capacity of water-bodies to break down biodegradable wastes and dilute nonbiodegradable ones. Water pollution problems are most serious in cities in developing countries where controls on industrial emissions are not enforced and sewers, drains, or sewage treatment plants are lacking. Sewage and industrial emuents can be treated before disposal if sewers exist and the regulatory authorities are effective. Agricultural and urban run-off cannot be treated and in many areas in both developed and developing countries it is a growing threat to the quality of lakes, rivers, and the groundwater. Fisheries have been damaged and drinking-water sources contaminated by pollution in many areas of the world.
The Commission stressed that:
The main goals of energy development have been to reduce the cost of producing energy, to make systems more efficient, and to open up previously untapped energy sources. Reducing the adverse environmental and health effects has also become a goal. More recently, concern about climatic change has emerged, since the combustion of fossil fuels, which accounts for nearly 90% of the world's commercial energy production, is the largest source of the so-called greenhouse gases.
People in developed countries use roughly ten times more commercial energy than those in developing countries and burn 70% of all the fossil fuel used, most of it for electricity generation, industry, transport, and domestic heating. To strengthen their economies and so provide the economic basis for good health, most developing countries will need to increase their fossil fuel consumption.
One of the Commission's central concerns was whether the need for developing countries to increase their use of fossil fuel can be met at the same time as the adverse health effects are reduced, especially indoor air pollution from coal and urban air pollution from fossil fuel use, within a global agreement that limits greenhouse gas emission.
Fossil fuels are the single largest source of atmospheric pollution; when burnt, they release in the air particulate matter, carbon monoxide and dioxide, oxides of nitrogen and sulfur, and metal compounds. More than 1000 million city dwellers are now exposed to high levels of air pollution. High levels of sulfur dioxide and particulates in urban areas have been associated with respiratory disease and increased mortality. Vehicle exhausts pollute the air in large cities with carbon monoxide and with lead (except where lead additives to petrol are no longer used). Exposure to the latter may impair mental development in children. Vehicle emissions also contribute to the formation of ozone and photochemical smog, which may decrease lung performance. Several studies have shown an association between levels of air pollution and respiratory symptoms, but it is still uncertain whether protracted exposure to low levels of air pollutants, such as occur in many cities of the developed and developing world, has any long-term effects on health. However, policies, regulations, and incentives can greatly reduce air pollution and increase the efficiency with which fossil fuels are used. Their adoption in many developed countries has improved air quality in a number of cities in recent years.
Indoor air pollution from the combustion of coal or unprocessed biomass fuels (e.g., wood, crop wastes) represents perhaps the largest energy-related source of ill health. Biomass fuels are used to meet the energy needs of nearly half the world's population. They are often burnt in open fires or inefficient stoves in poorly ventilated houses, and give off smoke and chemicals that contribute to respiratory disease, with long-term cardiovascular effects. Because of the presence of known carcinogens in the indoor air, an increased risk of lung cancer must be assumed. Women are generally responsible for cooking and looking after children in the home and they and their children are at greatest risk.
There are a number of alternatives to fossil fuels and unprocessed biomass fuels, including hydropower, nuclear energy, and solar power. Hydropower can bring extra benefits such as flood control and an increased supply of water for drinking and irrigation. However, dams can cause environmental changes that affect health: people living in the flooded area must be resettled, the quality and reliability of the water supply downstream are often reduced and, in the absence of appropriate control measures, the large area of water behind the dam can become a breeding ground for disease vectors (including those of schistosomiasis and malaria). Smaller hydro systems that draw power direct from flowing rivers can avoid most of these health, social, and environmental costs.
Nuclear energy is another option under normal working conditions, discharges from power plants result in exposures to levels of radiation about 1000 times lower than natural background levels. However, the risk of accidents and the difficulty of safely disposing of high-level radioactive waste are major concerns of the public. Moreover, nuclear power is rarely an appropriate choice for developing countries. The use of direct solar and wind energy is likely to increase, although it will be limited by cost and space requirements.
Use of electricity is likely to continue growing rapidly, since it provides the energy for virtually all communications and most lighting and mechanical work apart from road transport, and is essential to development and to the operation of medical services. The expansion of electricity supplies has led to increased exposure of the population to electromagnetic fields. Only since 1979 has it been suggested that such exposure may increase the risk of some cancers. No clear evidence has been obtained that such exposure is harmful, but the possibility requires investigation.
The Commission stressed five priorities for a national strategy:
Industrialization has made many positive contributions to health, among them increased personal incomes, greater social wealth, and improved services, particularly transport and communications. But industrial activities carry the risk of adverse health consequences for the workforce and the general population, either directly, through exposure to harmful agents or practices, or indirectly, through environmental degradation. Industrial emissions and products also threaten the global environment.
Industrial practices in both developed and developing countries produce adverse environmental health consequences through the release of air and water pollutants and the generation of hazardous wastes occupational diseases include silicosis, pneumoconiosis, lead and mercury poisoning, hearing loss, and skin diseases. Serious health risks are also faced by workers in small-scale or cottage industries, where exposure to toxic chemicals and accident rates are often higher than in large industries.
Industrial emissions have polluted many rivers, lakes, and coastal environments, especially in developing countries where pollution control is rarely enforced. A number of major accidents in developing countries such as the release of chemicals or explosions have been dramatic reminders of the adverse health effects of inadequate attention to safety and prevention. Only in a minority of countries are potentially dangerous industries sited away from population concentrations. In most countries too little attention is given to controlling the disposal of hazardous industrial and commercial waste so as to prevent human exposure and leakage into the environment.
There is a serious lack of quantitative data on the links between environmental agents and health effects. It has been difficult to establish the relation between industrial emissions and especially long-term low-dose exposure to them, and the health of the general population because factors other than industrial pollution are implicated. More is known about health risks inside industry and this information has contributed to the identification of health risks for the general public. Health problems are most severe in developing countries where fewer health standards are applied to limit workplace exposure. Even where standards exist, many countries have neither the funds nor the institutional structure to ensure that they are upheld, Partly for these reasons, there has been a transfer of some hazardous industries to developing countries.
The Commission stressed the need in each country for:
Environmental management is needed in all settlements to provide water, protect public spaces, remove wastes, and protect air and water quality. Even in a small village, water sources must be protected, and all households must be ensured sufficient water. Human and animal excreta must be disposed of in ways that minimize the possibility of human infection and of food and water contamination. As a settlement's population size and density increase from village to market town to major city, so too do the scale and complexity of the environmental management needed to ensure a healthy environment.
Rapidly growing urban centres are a particular challenge for environmental health. Urbanization is usually associated with the development of a more productive economy, and it can bring major benefits to health and the environment; the concentration of population and business lowers the unit cost of piped water and health services, sanitation, and the collection and treatment of household and commercial wastes. But in the absence of government action to ensure that the infrastructure and services are in place and pollution controlled, environmental health problems are greatly exacerbated.
These problems are particularly apparent in developing countries. Despite some slowing of the growth rates in many major cities in recent years, population growth still outstrips the ability of local authorities to provide even minimal levels of service. Local governments are often hampered in their efforts by a weak revenue base, poor financial management, and few trained personnel, and by budget cutbacks that cause a further decline in the coverage and quality of the water, sanitation, refuse collection, and health care services.
Housing problems are widely different in developed and developing countries. In the former the major issues concern the design, the physical structure, and the living environments of poor quality that are associated with physical and psychosocial problems contributing significantly to ill health in the urban areas affected. Legislation exists to ensure adequate standards in many of the areas listed above, but improved building and safety standards are still needed.
Housing should contribute to a sense of well-being and security. Poor housing is associated with social and psychological problems, including alienation, isolation, drug abuse, family break-up, and urban violence. Strong community networks can act as a buffer against the psychosocial effects of poor physical environments. Action to improve psychosocial health often combines improved services and employment opportunities. A related issue is noise, at home and at work, which can result in hearing loss, sleep disturbance, impaired mental performance, increased anxiety, and aggression.
Much of the housing in both the rural and the urban areas of developing countries lacks the most basic requirements for health. More than 2000 million people live in life-threatening and health-threatening housing and living environments. Most of the housing is overcrowded; space is nearly always at a premium, and many families live in one-room shelters or single rooms in tenements. Such overcrowding encourages the spread of acute respiratory infections, tuberculosis, meningitis, and intestinal parasites. Four or more persons to a room make it almost impossible to protect infants and children from burns or scalds and to store safely hazardous household substances such as bleach or kerosene. In urban areas a high proportion of housing is in illegal settlements and built of flammable materials; many dwellings are built on land prone to flooding, on steep hillsides or otherwise dangerous sites. The low commercial value of such sites means that the inhabitants have a greater chance of not being evicted.
Most of the poor have incomes that are too low to enable them to afford better housing with adequate space, security and services. Fear of eviction is a constant worry for most tenants and inhabitants of illegal settlements. The risk of infection, particularly from pathogens associated with excreta, is high. Most illegal settlements have only rudimentary water supply systems and no sewers or drains. An estimated 30-50% of the solid wastes generated in urban areas in developing countries is left uncollected.
Most poor people in developing countries have no health service to turn to when they are sick or injured. Some 1600 million have no access to health care. In the least developed countries more than half the population may have no access to health services. Health services are particularly important for vulnerable groups, especially for prevention and rapid treatment or common illnesses. Although the proportion of pregnant women and children covered by immunization has grown considerably in recent years, hundreds of millions remain unprotected and millions die each year from diseases that could be prevented by immunization. Most spending on health is still for curative services, usually in major hospitals, although preventive and community primary health care services are far more effective in reducing morbidity and mortality.
Enough knowledge and resources exist in most developing countries to improve housing and basic services at a relatively low cost. New participation partnerships between local authorities, nongovernmental organizations, and community organizations have shown this to be so and have proved cost-effective. Institutional frameworks at national and local level are needed to encourage and support these partnerships.
The Commission's recommendations included:
Certain environmental issues have health implications on a wider scale than the local or national level. They include the long-range transport of air pollutants, the transboundary movement of hazardous products and wastes, stratospheric ozone depletion, climatic change, ocean pollution and loss of biodiversity. Solutions are being sought mainly through intergovernmental agreements.
Sulfur and nitrogen oxides emitted from tall chimney stacks by fossil fuel-fired power stations are transported over long distances, often across national boundaries. In the atmosphere they are converted to acids and eventually fall to ground as acid rain or snow. This has acidified many poorly buffered lakes and soils and contributed to forest dieback and in many places (especially Central Europe) to the destruction of large forests. Health may be affected if acidified water is used untreated in water supplies. since it contains higher concentrations of metals, e.g., copper and lead from pipes, cadmium from plumbing solder, and mercury and aluminum from soils. Progress towards reduction in atmospheric pollution in Europe is being achieved through implementation of the 1979 Convention on Long-Range Transboundary Pollution and its protocols.
The ozone layer
The stratospheric ozone layer is being damaged by the release into the atmosphere of various chemicals, including chlorofluorocarbons used in refrigerants, aerosols, plastic foam blowers and other equipment, halons used by fire-fighting services, and various organic solvents. Depletion of the ozone layer is likely to lead to higher levels of biologically active ultraviolet radiation at the earth's surface. At certain wavelengths, UV radiation increases the incidence of skin cancer and cataract in humans and probably affects other organisms that have no protection against it. Small changes in recreational habits, such as the avoidance of sunbathing at midday and the use of protective clothes and creams, could do much to reduce the health risks. International efforts are being made to control the production and consumption of some of the chemicals responsible through the Montreal Protocol to the Vienna Convention on the Protection of the Ozone Layer. They should be strongly supported.
A related issue concerns the build-up of greenhouse gases in the atmosphere, thought likely to lead to global warming and a rise in the sea level. During the 1980s, carbon dioxide emissions, mostly from fossil fuel combustion, were responsible for more than half of the total warming effect, and chlorofluorocarbons for a quarter. Uncertainties about the magnitude, rate, timing, and distribution of any future warming make it impossible to predict the health implications quantitatively.
Heat stress and heat stroke, which can be fatal, are a direct effect that may become more common, particularly among susceptible groups such as the old, the young, and those with cardiovascular disease. The indirect health effects, however, are likely to be much more significant. Agriculture may be affected, in some areas by increased precipitations, in others by drought and desertification. Changes in rainfall may diminish the variety of crops available and lead to or aggravate food shortages. The distribution of vectors that carry the agents of infectious diseases is likely to be affected; diseases such as malaria may spread to areas where they are currently unknown. The adverse effects would be especially serious in developing countries, where lack of human, financial, and technical resources would hinder an effective response.
The seriousness of the possible health and environmental consequences of global warming is such that every effort should be made to reduce greenhouse gas emissions now, through individual efforts and through such measures as are now being developed by the United Nations.
Hazardous wastes are exported from developed to developing countries when the export cost is much lower than the cost of disposal in the country of origin. Disposal abroad is rarely accompanied by concern about the health of those involved or living near disposal sites. The growing concern about the health and environmental implications led to the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal. Once in force, this should considerably reduce the risks arising from such movement.
Large stretches of coastal waters, especially in semi-enclosed seas and where tidal flushing is limited, are heavily polluted by industrial and domestic wastes from rivers and outfalls, land run-off, and accidental spills. Biological and chemical pollution is high near river mouths and sewage outfalls. Fishing beds and beaches in their vicinity are at particular risk of contamination. Seafood poisoning and epidemics, such as the cholera epidemic in Latin America in 1991, may result from disposal of inadequately treated effluents into the sea.
Beyond the coastal waters the open sea is still relatively unpolluted. Although contamination by metals and organic compounds can be detected, the level is not yet significant for human health, and biological contamination from domestic effluents is virtually non-existent.
The need to improve the quality of coastal waters and to preserve that of the open ocean has led to the adoption of a number of international agreements. Their extension to the many ocean areas that are not yet covered should be greatly accelerated and ways and means for their rigorous implementation should be provided
Biodiversity is acknowledged as a condition for the long-term sustainability of the environment and its current destruction must be halted. Knowledge about many species is still limited, and their destruction may deprive the human population of future sources of food and medicine and of biological means of controlling pests and pathogens, However, the protection of biodiversity cannot be unconditional; there may be conflict between the need to improve health or provide necessities and the need to preserve a species, In such instances the health cost of ensuring the survival of species that are pathogenic to humans or are pests of food crops will need to be carefully taken into account, There seems for example to be little ground for preserving the human immunodeficiency, smallpox, or poliomyelitis viruses, malaria parasites, or guinea worm. An international convention on biological diversity is being developed by the United Nations Environment Programme
People need to have the means to acquire the resources on which health depends: safe food and water, fuel, and a secure shelter. They need to be protected not only from physical, chemical, and biological hazards, but also from crime and violence, which are encouraged by poverty and the use of drugs, and from injuries at their place of work. A healthy environment is not only a need, it is also a right; the right to live and work in an environment conducive to physical and mental health is enshrined in the Universal Declaration of Human Rights. Everyone shares the responsibility for ensuring that this right is duly acknowledged.
Everyone also shares responsibility for health and for passing on to the next generation a world whose resources are not depleted and whose natural systems are not degraded. There is a powerful synergy between health, environmental protection, and sustainable resource use. Individuals and societies who share the responsibility for achieving a healthy environment and managing their resources sustainably become partners in ensuring that global cycles and systems remain unimpaired.
The responsibility for action lies with individuals and with business. Governments have the responsibility of setting up the strategic and institutional framework within which action is taken. They should put in place the services, financial and other incentives, and controls that encourage individuals households. communities, businesses, and bureaucracies to promote health and sustainable resource use. They should take the lead in ensuring that the levels of consumption and waste generation within their boundaries do not damage global systems and deplete resources known to be finite.
There are three main global objectives:
Two principles are central to a healthier and more sustainable planet: first, more equitable access to resources within and between countries; second, citizen participation. Participation can promote health and environmental quality because it provides a means of organizing action and motivating individuals and communities. It enables individuals and communities to shape policies and projects to meet their priorities. Involvement in planning gives people the possibility to influence choices about the use of limited resources. Primary environmental care is one way of helping communities to apply their skills and knowledge to satisfy their own needs, improve their own environment, and promote the sustainable use of resources. Participatory political structures are a check on abuse of the environment, since citizens with clear rights and knowledge and access to a legal system that allows speedy redress can exercise a powerful restraint on those contravening health and environmental regulations.
The Commission's main general recommendations were:
Crude death rates are declining in developing countries while remaining steady in developed ones. However, comparing crude death rates may yield misleading results when, of two populations, one has a larger proportion of young people and the other of elderly people, The mortality experience of a population is better expressed in terms of life expectancy at birth, since this makes possible comparisons unbiased by age structure.
Life expectancy at birth has been increasing throughout the world, but the scale of the improvement is very different in developing and developed areas (1). While life expectancy, in the developing world is much the lowest, there are exceptions. Thus, the temperate part of Latin America (Argentina, southern Brazil, Chile, Uruguay) has a mortality pattern close to that of developed countries, and Sri Lanka has achieved a life expectancy of close to 70 years in 1990, from nearer 60 years in 1950. On the other hand, all African countries had a very low life expectancy in the 1950s, and only a few, mostly in northern Africa, are expected to achieve an expectancy of 70 years by early next century.
Among developed countries the differences are wide, though less pronounced than between developed and developing countries. Within Europe there are significant differences between east and west, the life expectancy being consistently lower in east as compared with west Europe (71 compared with 76 years). The life expectancy for men has in fact been decreasing in Hungary, Romania, and the former USSR, while remaining steady in the other east European countries. Most of the recent gains in life expectancy in developed countries (up to 58% in Japan between 1980 and the mid 1980s) have been the result of reduction in mortality among elderly people (2). In developing countries the gains are due largely to reduction in the mortality of the young, but statistics are inadequate to quantify the effect.
Infant and child mortality
A major component of mortality is the death of infants in their first year of life. Infant mortality rates have been declining sharply in both developed and developing countries. While the rate of decline has recently been slowing down in a few countries, only in countries with a very high prevalence of AIDS or long exposure to war or internal strife has the decline been halted or reversed. National statistics, however, are likely to conceal local areas where the trends may be quite different.
Causes of mortality
The distribution of the causes of death helps explain differences in mortality experienced over time and from population to population. It also provides an insight into the burden of disease by serving as a crude proxy for the morbidity experienced. But it only informs us of the loss of life experienced in a population and tells us little about the sufferings and loss of productivity among the victims of disease or the physically or mentally disabled. Direct information on the incidence and prevalence of diseases would be a better indicator but is available only from surveys of limited temporal and geographical scope. There are severe limitations to mortality analysis, particularly when it is carried out for comparative purposes.
Although causes of death are recorded systematically in all developed countries (3), differences in diagnostic, therapeutic, and reporting practices may affect comparisons between countries and between different times within most countries. In most developing countries causes of death are not recorded systematically. The pattern of mortality is therefore obtained indirectly, on the basis of limited studies in a few areas, extrapolated regionally and globally.
Age-standardized mortality figures are not generally available for developing countries. To make some comparison possible between developed and developing countries, the estimated number of deaths from various causes and their percentage contribution to the total number of deaths are given in Boxes 7a and 7b. There are dramatic differences between the two patterns. Even if they reflect in part a different age composition in the two groups of countries, no demographic consideration can bridge the tenfold disparity in mortality from infectious diseases in general or the twentyfold difference in mortality from tuberculosis. The current mortality rate from tuberculosis in developing countries equals the figures that used to be recorded in the United Kingdom (about 1000 per million per year in the 1920s, down from 3500 per million per year at the turn of the century (4)), while only 2 per 10 million occur now (5).
The excess mortality from gastrointestinal and respiratory diseases in developing countries is also of the same order as was recorded at the turn of the century in some of the European countries that now enjoy among the highest standards of health. Cholera, dysentery, and typhus claimed 3000 deaths per million in the United Kingdom in the 1850s, 100 times more than in 1971 (6), and mortality from respiratory diseases also experienced a sharp fall, undoubtedly as a result of improvements in the quality of the water supply, food safety and sanitation, as well as in the availability of adequate medical care and medicines.
In contrast, neoplasms and cardiovascular diseases account respectively for 21% and 54% of all deaths in developed countries and for 7% and 17% in developing countries. Mortality from these causes is likely to rise in the future in developing countries, as the life span increases and lifestyle habits, especially smoking and diet, approach those of developed countries.
The extent to which the health situation in a country can be improved by modifying its environment is difficult to quantify. Supplying water and food in adequate amounts and of acceptable quality, and breaking the faecal-oral chain are essential to reduce gastrointestinal diseases. These had already declined significantly in most of Europe and North America well before the introduction of therapeutic drugs and oral rehydration therapy. The high mortality of infectious respiratory diseases is probably the combined result of overcrowding (which facilitates infection) and poor nutrition, but much could be prevented or alleviated by immunization and the use of modern drugs. The environment has an indirect role in mortality from circulatory and many other chronic diseases (e.g., cirrhosis of the liver, stomach ulcers, diabetes) and is likely to have some in the causation of chronic obstructive lung disease. Its role in the etiology of neoplasms is briefly reviewed in Box 8.
The conditions in which environmental factors are most prominent are tropical diseases, which to a large extent are caused by infection by parasites requiring one or more intermediate hosts and vectors for their development. The best known example is malaria, the vectors of which are a number of mosquito species. Malaria exacts a toll of more than one million deaths a year, mostly among children, and seriously reduces the productivity of those affected. In general, intermediate hosts and vectors need precise conditions of temperature and moisture for their survival and for the development of the parasite inside them. They are often dependent on the presence of animal reservoirs with very specific habitats. The fight against vector-borne diseases may therefore involve many fronts--the reduction of sites that favour breeding, the rational use of insecticides, the maintenance of passive immune protection of children through protracted breast-feeding, better sanitation and personal hygiene, even in some cases simply the wearing of boots while environmental measures can be effective when coupled with other appropriate action, mismanagement of the environment in the tropics may result in the further spread of disease by rendering the environment more favourable to a vector or widening its habitat.
Mortality statistics can provide only a broad picture of the disease burden to which people are exposed, especially when considered at the necessarily very high level of aggregation presented in Boxes 7a and 7b. A more detailed assessment of the burden will emerge when the main human activities impinging on the environment have been reviewed.
1. United Nations. World population prospects: 1990. New York, 1991 (Document ST/SA/SER.A/120).
2. World health statistics annual, 1977-89.
3. Lopez, A. Causes of death: an assessment of global patterns of mortality around 1985. World health statistics quarterly, 43: 91-104 (1990).
4. Lancaster, H.O. Expectations of life. New York, Springer-Verlag, 1990.
5. World health statistics annual. Geneva, World Health Organization, 1989.
6. McKeown, T. The role of medicine. Oxford, Blackwell, 1979.