Critical Links: Population, Health and the Environment

The impact of the world’s 6.3 billion people on the environment is unprecedented. Humans had a negligible effect on the environment 3,000 years ago when fewer than 100 million people lived on Earth, but by the early 21st century, we have altered more than one-third of Earth’s ice-free surface, and threatened the existence of many plant and animal species.

However, the number of people is just one factor driving environmental change. Where people live, and the rate of population growth are important, as well as other forces such as public policies, technological developments, and culture. All of these can ease or worsen the pressures that demographic factors place on society and the environment.

There is a relationship among population, health, and environment, but it is a complex one. It encompasses the study of human population growth, consumption, and resource use, as well as the study of the natural world, its climatology, genetics, biochemistry, and population biology. Cooperation between natural and social scientists has been complicated by major differences in paradigms, assumptions, and definitions.

Among the many questions scientists have investigated when studying the relationship among population, health, and the environment, is the question of whether population growth is good or bad for the environment and human well-being. The answer to this question is neither straightforward nor simple.

Consider the case of urbanization. A population shift toward urban areas means that a larger share of people will have access to health care, education, and other services, and living standards are likely to improve. At the same time, dense urban populations may produce more waste than the environment can absorb, leading to significant air and water pollution and a greater incidence of infectious and parasitic diseases.

Environmental conditions affect the spread of communicable diseases, which account for about one-fifth of annual deaths worldwide. An estimated 60 percent of the global burden of disease from acute respiratory infections, 90 percent from diarrheal disease, 50 percent from chronic respiratory conditions, and 90 percent from malaria could be avoided by simple environmental interventions. More than 60% of the diseases associated with respiratory infections are linked to air pollution. Most of this pollution comes from the burning of fossil fuels.

Outdoor air pollution has stabilized or declined in Western Europe and North America since 1970, according to the World Health Organization’s (WHO) air quality standards, while it has continued to increase in the less developed countries. Overall, children are at greater risk from environmental health problems than adults. Children under age 5 breathe more air, drink more water, and eat more food per unit of body weight than adults do, so they may experience higher rates of exposure to pathogens and pollutants.

Indoor air pollution also poses serious health risks. Half of the world’s households use biomass fuels such as wood, animal dung, or crop residues that produce particulates, carbon monoxide and other pollutants. Studies in less developed countries have linked indoor air pollution to lung cancer.

In addition to air pollution, new threats have been posed by industrialization. Since 1900, modern industry has introduced almost 100,000 previously unknown chemicals into the environment. Many have found their way into the air, water, soil and food. Many of these chemicals are cancer producing, promulgate genetic damage, and brain and bone damage.

Efforts to understand and manage the relationships between population, health and the environment, and to enact appropriate public policies are underway through field studies; university programs to educate policy-makers about population, health and environment relationships; international projects to document, evaluate, and disseminate information; and international conferences and working groups. These efforts contribute to a knowledge base, test methods for appropriate field interventions, engage policy makers in concrete action, and capitalize on human ingenuity to balance human needs with environmental protection.

(Summarized from POPULATION BULLETIN, Sept. 2003 pp3-43, Article by Roger-Mark DeSouza, John S. Williams, and Frederick A.B. Meyerson. Copyright© Population Reference Bureau, Inc., September, 2003.