Toward measuring the impact of ecological disintegrity on human health

Ecological integrity refers to the ability of environmental life-support systems to sustain themselves in the face of human-induced impacts. We used a correlational, aggregate-data study design to explore whether life expectancy, as a general measure of population health, is linked to large-scale declines in ecological integrity. Most of the data were obtained from World Resources Institute publications. Selected surrogate measures of ecological integrity and gross domestic product (GDP) per capita (as a socioeconomic confounder) were modeled, for the first time, using linear regression techniques with life expectancy as the health outcome. We found a modest relation between ecological integrity and life expectancy, but the direction of the association was inconsistent. When GDP per capita was controlled, the relation between ecological integrity and life expectancy was lost. GDP per capita was the overwhelming predictor of health. Any relation between ecological integrity and health may be mediated by socioeconomic factors. The effect of declines in ecological integrity may be cushioned by the exploitation of ecological capital, preventing a direct association between measures of exposure and outcome. In addition, life expectancy may be too insensitive a measure of health impacts related to ecological decline, and more sensitive measures may need to be developed.