THE NATURAL ENVIRONMENT AND HUMAN HEALTH

Houston’s corner of Texas is naturally one of the most complex and diverse ecosystems in the world. Although located in the epicenter of a vibrant ecosystem with rolling prairies, lush bayous, hardwood forests and fertile estuaries, little of this natural legacy now remains in the Houston metropolitan area, observed Winifred J. Hamilton, director of the Environmental Health Section of Baylor College of Medicine. Indeed, Houston has an average per-capita land consumption (0.259 acre per resident) that is more than twice that of Los Angeles (0.110 acre) (Kolankiewicz and Beck, 2001), and it has more paved freeway miles (6.1 miles per 1,000 persons) than any other city in the world (U.S. Department of Transportation, 2003).

The impact of increased urbanization and industrialization is evident. The greater metropolitan Houston region contains 406 Toxic Release Inventory (TRI) facilities, 17 toxic-waste incinerators, 16 National Priority List (NPL) Superfund sites, and 85 Superfund sites overall, Hamilton noted (U.S. Environmental Protection Agency, 1998). It is also the location of one of the largest coal-burning power plants in the United States. And the 2.7 million vehicles in this area are driven a total of 125 million miles each day. Per person, she said, area residents drive an average of 39 miles each day—more than any other city in the nation (with 68 miles per person projected for 2025) (U.S. Department of Transportation, 2003; Houston-Galveston Area Council, 2004).

Increased urbanization amplifies exposure to environmental health hazards and is likely to have an adverse effect on human health and well-being. For example, a study of the Los Angeles metropolitan area suggested that each year nearly a thousand new cases of cancer for every one million residents may be caused by exposure to diesel-particulate emissions (South Coast Air Quality Management District, 1999). Other studies have suggested an increased cancer incidence among people who live near refineries (Macdonald, 1976; Pekkanen et al., 1995; Wu et al., 1997), and still other studies have observed that hospital admissions are significantly higher among people who live near major roadways (Buckeridge et al., 2002; Oftedal et al., 2003). These examples suggest that environmental pollutants from many sources are a health concern for the Houston region as well.

Increased urbanization amplifies exposure to environmental health hazards and is likely to have an adverse effect on human health and well-being.

Winifred J. Hamilton

Further, while degradation of the natural environment generally goes hand in hand with increased risks to human health, some individuals—particularly the poor and disenfranchised—are disproportionately exposed to environmental health hazards, noted Hamilton, and may be more susceptible to their adverse



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