Despite vast improvements in health globally over the past several decades, environmental factors remain a major cause of sickness and death in many regions of the world. In the poorest regions, one in five children do not live to see their fifth birthday, largely because of environmentally related and preventable diseases. That number translates into 11 million childhood deaths each year, mostly due to illnesses such as diarrhea and acute respiratory infections. Insect-borne diseases also exact a heavy toll; malaria alone claims 1 to 3 million lives a year, most of them children.
Environmental threats to health are by no means limited to developing countries. In the United States, some 80 million people are exposed to levels of air pollution that can impair health. In China, which has one of the world’s fastest growing economies, 2 million people die each year from the effects of air and water pollution, according to one recent estimate. Nearly 100 countries, both developed and developing, still use leaded gasoline, unnecessarily exposing their citizens to a pollutant long known to cause permanent brain damage.
Environmental health problems vary dramatically from region to region, reflecting geography, climate, and perhaps most important, a country’s level of economic development and policy choices. Many environmental health problems are associated with poverty and a lack of essential resources, chief among them sufficient and clean water, food, shelter, fuel, and air. Indeed, the World Health Organization has called poverty the world’s biggest killer. These environmental problems, prominent at the household or community level, underlie the 17 million deaths each year from infectious diseases.
Other environmental threats to health are associated with development itself, when it is pursued without proper safeguards for the environment. Without question, economic growth and social development are critical for improving human health and well-being. Yet, if not well managed, economic growth can exact a major toll on environment and health. It is not a coincidence that some of the booming Asian economies also have some of the worst air pollution in the world.
In many developing countries today, populations are in double jeopardy, facing both the unfinished agenda of traditional environmental health problems, such as insufficient clean water and sanitation, as well as the emerging problems of industrial pollution. In these countries, both pesticides and feces may contaminate drinking water; likewise, air pollution may stem both from the household burning of dirty fuels and the industrial use of fossil fuels.
New indexes developed for this report attempt to capture the geography of environmental threats to health. Portrayed in maps, these indexes highlight those countries where traditional risks are high, and also vast areas such as India and China where traditional and modern risks coincide. In the more developed countries, the indexes show that many populations still face threats from avoidable hazards such as leaded gasoline. Although preliminary, these indexes suggest where policy interventions could improve both environmental quality and human health.
Although useful for painting a picture in broad strokes, these indicators cannot capture serious disparities in risk that occur within countries. For example, although the United States overall faces low environmental risks to health, the prevalence of asthma is increasing among poor and minority populations, and environmental factors are believed to be contributing to that increase. Similarly, lead exposures are typically far higher among poor, inner-city children than other groups. This unequal burden of risk, closely tied to poverty, is described in detail in the text. Nor do country-level indicators reveal another inequity: the disproportionate share of global environmental threats created by the wealthiest countries, who consume more energy and resources per capita than do poorer countries. The wealthy countries, for instance, bear the greatest responsibility for releasing the greenhouse gases that threaten to change global climate, with myriad potential health effects.
This special section describes the complex links between the environment, development, and health. It explores the ways in which environmental factors, and particularly environmental change, can degrade health—either directly, by exposing people to harmful agents, or indirectly, by disrupting the ecosystems that sustain life. The section then examines how improved environmental management can reduce these risks and preserve both human health and environmental quality.
Why focus on the role of environment in health? Admittedly, environmental factors are by no means the only, or even the major, cause of ill health globally. Environmental factors predominate in poorer countries, for instance, but play a much smaller role in undermining health in the wealthier countries, where voluntary behaviors such as diet and smoking are larger determinants of health. In both settings, however, environmental factors deserve increased policy attention because they are avoidable causes of ill health.
Much has been done globally in the past few decades to improve health. Governments, communities, international agencies, donors, and nongovernmental groups have worked together to make widely available such life-saving interventions as vaccines and oral rehydration therapy. Many millions of dollars have been spent on medical research, although arguably not enough on tropical diseases that cause so much misery and claim so many lives throughout the developing world. These health-care strategies are essential and deserve increased support. However, supplementing these approaches with preventive strategies that intervene earlier in the disease process and stop harmful exposures from occurring in the first place would bring additional gains, often at relatively modest cost.
This report attempts to illuminate these points of intervention by exploring the driving forces and trends that underlie many of today’s environmental health problems. Three trends in particular stand out in terms of their profound impact on the physical environment and their enormous potential for influencing human health: the intensification of agriculture, industrialization, and rising energy use—in particular, fossil fuel consumption.
All of these trends play a vital role in economic development patterns worldwide, yet all can be a source of avoidable ill health as well. For instance, agricultural intensification can expose workers and communities to toxic pesticides. Land clearing and irrigation projects can facilitate increases in vector-borne diseases such as malaria and schistosomiasis. Industrialization, which is so critical to economic growth, can also bring exposure to heavy metals and other toxic contaminants. Rising energy use is largely responsible for air pollution that blankets many of the world’s cities and also has the potential to alter the Earth’s climate.
This report then describes a range of environmental interventions—from simple and local to complex and international—that can mitigate these problems. Many of these problems are hard to address. Indeed, the question of how to expand access to water and sanitation has defied simple solution for decades. Yet, tackling fundamental problems will yield myriad benefits, not just in terms of health. The provision of water and sanitation and associated interventions, for instance, would not only reduce disease and improve human dignity but could also help combat poverty if the time formerly spent collecting water or caring for sick children could be devoted to education or income-generating activities.
Other interventions, too, promise multiple benefits beyond the health arena. Curbing fossil fuel consumption could save lives immediately by reducing levels of ambient air pollution. In addition, the same strategy could help avert long-term climate change and its predicted ecological, economic, and health costs. Similarly, adopting more environmentally benign forms of agriculture—approaches that use fewer agricultural chemicals and cause less ecological disruption—would help to reduce both acute and chronic health risks associated with exposure to harmful pesticides. At the same time, reducing the use of fertilizer and improving watershed management could lessen agriculture’s toll on coastal waters—particularly the harmful algal blooms and fish kills that threaten not only ecosystem health but human health as well.
In addition to these large-scale changes, the report calls attention to situations in which the problems and solutions are relatively well understood. Removing lead from gasoline, for instance, could immediately reduce environmental threats to health. Similarly, the report illustrates the many benefits possible if concerns about environmental threats to health are incorporated into development planning at the outset. Experience has shown it is possible to anticipate and prevent some of the problems associated with development. Dams can be built so that they do not provide habitat for disease vectors. Factories can be sited so that they do not contaminate groundwater. But achieving such results requires coordination and communication among agencies that do not often interact, such as government ministries of health, agriculture, economics, and the environment, and also international aid agencies. Making the environment a central component in public health strategies is essential to ensure health for everyone in the 21st Century.