http://www.paho.org/english/hdp/hdp01.pdf

This economic divide has not gone unnoticed by public health researchers, who have produced a substantial literature documenting and discussing the links between increasing economic inequality and poorer health. Technically, it is possible to separate individual-and community level effects, but are the determinants really separate? For example, social and economic policies that differentially distribute and reward high-tech and low-skilled labor will differentially attract populations that vary by level of individual income and wealth.