Some recent evidence shows that hazardous waste sites in the United States display an inverted U-shaped relationship with county income.26 That is, as income in a county rises, the number of hazardous waste sites at first increases and then decreases, with a turning point of between $17,000 and $21,000 per capita. (The authors also find evidence of “environmental racism” [Chapter 7]. Controlling for income, a higher white population saw a significant drop in the number of hazardous waste sites.)
Do you take the evidence on income to mean that richer counties ultimately generate less hazardous waste? Why or why not?