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World Resources 1996-97
(A joint publication by The World Resource Institute, The United
 Nations Environment Programme, The United Nations Development
 Programme, and the World Bank)
(Data edited by Dr. Róbinson Rojas)

2. Urban Environment and Human Health


Although overcrowding, air pollution, uncollected garbage, and other deficiencies in the physical environment frequently represent the most obvious manifestations of urban environmental health problems, cities must deal concurrently with the less visible problems of the urban social environment. Although debate continues, it is likely that differentials in mortality among urban residents from noncommunicable diseases such as heart disease and cancer are related to the social rather than the physical environment within cities.

The contribution of the urban social environment to ill health is increasingly recognized in the developed world, where many physical risks have been largely addressed. For instance, the recent Helsinki Declaration on Action for Environment and Health in Europe emphasizes that the exceptionally high levels of unemployment (especially among young people)caused by economic and technological changes can have adverse effects on physical and mental health. The declaration also warns that a lack of action on these issues, when combined with already unacceptable levels of deprivation and squalor in many places, could threaten "the very cohesion of society" (128). Recognition of the role of social factors in public health is slower in poorer cities in the developing world, where physical risks still constitute a major health threat. Even so, socially related health problems are assuming increasingly large proportions. As is the case with physical risks in the urban environment, it is the poorest groups who are the most severely affected.

Socioeconomic Status

As is clear from earlier sections, socioeconomic status is the most obvious social factor involved in determining the health risk that an urban resident faces, because it largely determines his or her exposure to physical environmental threats and to amenities such as adequate housing. It is no surprise that access to sanitation and running water, for example, is closely related to income and education levels. In Sao Paulo, Brazil, districts with the lowest income and literacy rates had five times lower per capita consumption of water than districts with the highest income and literacy rates (129).

Housing conditions in the developed world are different from those in developing countries, but the general pattern--that more socially deprived groups are more exposed to poor living conditions--holds true. In England, for example, the proportion of households reporting damp spots and molds, both of which are implicated in the development of asthma in children, is strongly related to their social class (130).

The urban social environment, however, also influences health in less obvious ways. The higher rates of socially related health conditions among the disadvantaged are often traced to risk behaviors such as smoking or drinking, which, in turn, are often responses to social or economic stress. For instance, in the United Kingdom, rates of smoking, drinking, and, in some cases, drug abuse are higher among unemployed adults, and these behaviors contribute to the higher rates of heart disease found among the unemployed (131).

Both heart disease and cancer used to be considered diseases of affluence, because they are linked with behaviors such as sedentary lifestyle, stress, and diets high in fat and sodium that are typically associated with the wealthy. Yet, recent data suggest that mortality rates from chronic disease in both developing and developed nations are highest among the poor (132).

Social Marginalization

Urban areas are often diverse ethnically, culturally, and economically. Residence time in the city also varies widely, from longtime residents to recent immigrants. The close interaction and interdependence of these diverse groups within cities and towns can enhance social cohesion. Conversely, diversity in urban populations can lead to social stress, alienation or disenfranchisement of some groups, and feelings of insecurity by individuals or communities within the overall society. All of these contribute to what is known as social marginalization.

Groups in cities can become marginalized in economic terms or through cultural differences from dominant groups. The two tend to work together: particular cultural groups in cities may be disadvantaged in terms of access to education and employment opportunities. Increasingly, social marginalization is believed to exact a toll on human health, largely through behavioral changes such as seeking relief through smoking or alcohol or substance abuse.

Studies in Seattle, Washington, in the United States, suggest the consequence of social and economic marginalization for Native Americans and Alaska Natives in urban areas. Both groups have much higher death rates from injuries and alcohol-related causes than urban whites or rural Native Americans and Alaska Natives. Both groups also have a higher incidence of having babies with low birth weights. Tobacco and alcohol use, adolescent pregnancy, and inadequate prenatal care are linked to low birth weight (133).

Relative Inequality

Although absolute poverty is obviously a critical factor affecting a person's access to the goods and opportunities essential for a healthy, productive life, increasing evidence suggests that relative poverty, or relative inequality, may be just as important (134). Relative inequality or social deprivation is more broadly defined than absolute poverty, encompassing not only the lack of economic resources but also the inability to acquire the same amenities and types of services that typically accrue to other, more privileged, members of society (135).

Relative inequality refers to the way in which a person sees himself or herself in relation to neighbors or other groups in society. It implies that the social meanings attached to inferior facilities, job opportunities, or other privations are just as important as exposure to the facility or the job itself in determining health (136).

Intriguing evidence to support the notion of relative inequality as a major determinant of health comes from recent studies suggesting that it is countries with the narrowest gap between rich and poor that enjoy the best national health--not those that spend the most money per capita on health in absolute terms (137).

Differential rates of urban violence, described earlier, have also been linked to relative deprivation. This is perhaps not so surprising, since rich and poor often live and interact closely within cities, making the differences between them obvious to each group.

Accra and Sao Paulo

The importance of social environmental factors in urban health is borne out by data on differential mortality among different socioeconomic groups in Sao Paulo, Brazil, and Accra, Ghana. Sao Paulo is a relatively wealthy city of more than 9.6 million people, whereas Accra is a rapidly developing city of 1.3 million people (138) (139).

Case studies in these two cities examined differences in mortality from circulatory diseases, infectious and parasitic diseases, and respiratory diseases among different socioeconomic groups across all age groups. In Sao Paulo, the study was extended to include external causes (homicides and traffic accidents) because they account for a significant share of deaths. Consistently, the disadvantaged have higher rates of mortality than their better-off neighbors from both infectious diseases and socially related conditions such as heart disease.

In these studies, the cities were divided into four zones, from worst to best, according to several indicators of poverty and environmental quality. The indicators included income, education, age and ethnicity of the community, per capita water supply, access to sewage facilities, and population density. (See Figure 2.3.)

As Figure 2.3A shows, in Accra, age-adjusted rates of mortality from circulatory diseases were more than two times higher for the 46 percent of the city's population in the worst zone compared with the mortality rates in the most affluent zone. Mortality from infectious and parasitic diseases was likewise about twice as high in the worst zone as in the best zone, as was mortality from respiratory diseases (140).

In Sao Paulo, while the overall rate of mortality from infectious and parasitic diseases was much lower than that in Accra, the same differential exists between the affluent and the disadvantaged, with those living in the worst zone being nearly twice as likely to die from such an infectious or parasitic disease. The differential in mortality rates from heart disease between affluent and disadvantaged in Sao Paulo was much smaller than that in Accra. It was still significant, however, as was the differential for respiratory diseases. In Sao Paulo, the death rates from accidents and homicides were also nearly twice as high in the worst zones of the city as in the best zone (141).

These studies indicate that for urban adults living in poor conditions within Accra and Sao Paulo, the health risk of communicable diseases appears to be compounded by high risks of circulatory diseases and, in Sao Paulo, by epidemic rates of traumatic health problems such as accidents and homicides. Such findings suggest the complex nature of health impacts inflicted by the "web of insecurity" (142) entailed in the deprivation of many cities of the developing world.

Both cities are clearly caught in an incomplete health transition, with chronic and infectious diseases coexisting, and the disadvantaged most subject to this dual risk.

References and Notes

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