Chapter 2. Changing environments, changing health

Linking Environment and Health describes in detail the environment’s role as an important determinant of human health. Given this role, changes in the environment will influence health in the future, for better or for worse. The three trends discussed in this chapter the intensification of agriculture, industrialization, and rising energy use stand out in terms of their profound impact on the physical environment and their enormous potential to influence human health. While each trend has the potential to bring about dramatic health improvements, each also shares the potential to degrade the physical environment and increase human exposure to environmental threats through pollutant emissions and resource depletion.

Predicting the global environmental changes that will occur because of human-directed activities in the future and how these changes might affect human health is difficult at best. Even the most sophisticated models describing future interactions among environmental, economic, technical, and social developments are simplistic and often misleading (1). In addition, these three trends are interdependent (2). Looking forward is necessary, however, because doing so enables one to anticipate where future health problems might arise. Future energy demand in China and India provides an apt example. By the year 2015, commercial energy use in these two countries alone is expected to more than double as the result of population growth, economic growth, and consumer demand for modern products, although per capita energy consumption will remain well below that of developed nations (3). The magnitude of air pollutants and greenhouse gases emitted by these countries will depend largely on how energy demand is met, with attendant consequences for human and indeed for planetary health. Foresight can help development experts identify preventive steps that could improve human health as well as protect the environment; some of these interventions are identified in Improving Health Through Environmental Action.

To understand these three trends, one must first understand the context in which they are occurring. All three trends discussed in this section are influenced by the following driving forces: population growth and urbanization, economic growth and consumption, and the persistence of poverty and economic inequalities (4).

Population growth is a fundamental force underlying all others. On a positive note, recent estimates suggest that population growth rates are slowing faster than demographers had projected. The number of people added to the world’s population each year is thought to have dropped from a peak of 87 million in the late 1980s to 81 million in the first half of the 1990s; demographers project that the world’s population in 2050 will reach about 9.4 billion people (5).

The Global Economy is Burgeoning
Gross World Product, 1970-95

Source: The World Bank, World Development Indicators 1997, on CD-ROM (The World Bank, Washington, D.C., 1997).

The global economy is burgeoning. In the past three decades, global GDP has expanded from roughly US$9.4 trillion to more than US$25 trillion. (See The Global Economy is Burgeoning.) Average per capita incomes have more than tripled (6). Although the developed countries account for the lion’s share of this wealth, economic growth in developing countries has nonetheless been enormous, with per capita incomes growing nearly 3.5 percent per year during this period (7). This growth is expected to continue well into the middle of the next century.

The liberalization of both trade and investment across borders has helped fuel this economic growth (8). Global trade rose an estimated 45 percent in nominal terms between 1990 and 1995, from US$4,345 billion to US$6,255 billion (9). Liberalization has also greatly increased the flow of private capital into developing countries. In 1995 alone, the flow of net private capital into low-income and middle-income countries totaled about US$180 billion, roughly 4 times more than in 1990 (10). Official flows amounted to just US$64 billion in 1995. The nature of private capital flows is also changing, moving away from investments in emerging stock markets and toward direct investments in projects such as factories, power plants, and roads (11). Between 1988 and 1995, multinational corporations invested nearly US$422 billion in new factories, supplies, and equipment in developing countries (12).

Such economic growth creates resources and opportunities for improving the quality of living conditions, which, of course, is essential to good health (13). Indeed, global health conditions have improved more in the past half century than in all of previous history (14), demonstrated through rising life expectancy and declining child mortality rates (15). Yet, this generally positive picture is still colored by regional differences and growing disparities between rich and poor. In some developing countries, continued population growth and poverty have impeded economic and social progress. The most rapid population growth rates are concentrated in the poorest regions. Africa continues to have the highest population growth rate (2.7 percent), well above the average rate (1.8 percent) for developing countries as a whole (16).

As described in Poverty, Health and the Environment, poverty and inequity are two critical determinants of human health. Despite economic progress, it appears that the health problems linked with economic stagnation, poverty, and environmental degradation are likely to continue well into the future. Global economic growth has failed to alleviate poverty for a large share of the world’s people. Despite an overall rising global economy, the absolute scale of poverty continues to grow. Large parts of the developing world have been bypassed by the past three decades of economic growth. Three fourths of the least developed countries, home to more than 400 million people, suffered negative economic growth during the 1980s and early 1990s (17).

A recent analysis by the World Bank found that, although the percentage of poor decreased slightly between 1987 and 1993, approximately 1.3 billion people in the developing world still subsisted on less than US$1 a day in 1993. Indeed, in each of the world regions except East Asia, the absolute number of poor increased (18). (See Despite Economic Growth, Poverty Remains Pervasive.) Poverty continues to be concentrated in rural areas. Some 30 million people in developing countries are landless, and an additional 138 million are near-landless; these numbers appear to be growing, especially in South Asia (19).

Despite Economic Growth, Poverty Remains Pervasive
Number of Persons Living on Less Than One Dollar Per Day, 1987-93

Source: The World Bank, Poverty Reduction and the World Bank: Progress and Challenges in the 1990s (The World Bank, Washington, D.C., 1996). p. 4. Note: Based on US$1 per day using purchasing power parity.

Urban Populations Could Double by 2030
Urban Population Growth by Region, 1950-2030

Source: United Nations Population Division.

Many experts believe that urban poverty will soon overtake rural poverty in significance. By the year 2025, 5 billion people are expected to live in urban areas, 4 billion of them in cities in the developing world. The highest rates of urban growth are in Africa and Southeast Asia. (See Urban Populations Could Double by 2030.) In general, urbanization brings improvements in human health because of improved access to education and health services in cities (20). In urban areas of Indonesia, for instance, the mortality rate of children younger than age 5 is 84 per 1,000 live births, as compared with 116 in rural areas (21).

But statistical averages hide the health impacts associated with poverty in urban slums or squatter shantytowns where growing proportions up to one half in some cases of urban populations live. Estimates suggest that, depending on the definition used, between 25 and 50 percent of the world’s urban population now live in extreme poverty (22)(23). While the exact definitions of urban poverty vary, inadequate housing lacking water, sanitation, or garbage collection is a primary characteristic or urban poverty (24). The links between urban poverty and health are illustrated by the resurgence of tuberculosis among the poor in cities of the developed world as well. (See Tuberculosis and Urban Inequality.)

In addition, the gap between rich and poor is widening, both within and among countries(25). Table 2.1 titled The Gap Between Rich and Poor is Widening, shows how the poor compare in income with the national average income of several countries(27).

As poverty continues to degrade health in much of the world, serious concerns have arisen over the long-term viability of consumption patterns in the developed world, which are now appearing in the rapidly industrializing countries. Paralleling growth of the world economy, resource and material consumption has accelerated at a rate unprecedented in human history. Over the past 45 years, the richest one fifth of the world’s population has doubled its per capita consumption of energy, meat, timber, steel, and copper, and quadrupled its rate of car ownership. By contrast, the per capita consumption of the poorest one fifth has barely increased (28). One byproduct of this increased consumption is that developed countries account for about 70 percent of carbon dioxide (CO2) emissions (29) with less than 20 percent of global population.

New technologies can help to increase the efficiency of resources, delivering equivalent or improved services while substantially reducing environmental and health burdens (30). This was the case in the 1970s and 1980s, when energy intensity (the energy required per unit of economic output) fell by about 2 percent per year. It has since leveled off (31). However, even with conservation efforts and more efficient technologies, some believe that if long-term environmental protection is to be achieved, consumption patterns themselves will need to change.

Against this backdrop, this chapter explores the health consequences of the intensification of agriculture, industrialization, and rising energy use, paying particular attention to their effects on the poor in developing countries. The chapter examines the ways in which all three of these trends can increase exposure to hazards in the environment to both biological and chemical agents. Strategies for preventing some of these harmful exposures are explored in “Chapter 3. Improving Health Through Environmental Education”.