Cumulative environmental burdens and vulnerable populations: taking into account the intensity and count of burdens in environmental justice analyses

Abstract Most studies examining demographic disparities in the distribution of environmental burdens have examined only one burden at a time. Few have examined how multiple burdens are concentrated and distributed among the American population. The objective of this study was to examine how multiple (13) environmental burdens are concentrated and how concentrated burdens are associated with where vulnerable populations reside. We utilized nationally consistent data from the U.S. Environmental Protection Agency’s EJScreen database. EJScreen includes 13 environmental burden indicators and five racial/ethnic and socioeconomic indicators. The concentration of environmental burdens was examined by taking into account both the intensity of individual burdens and the count of burdens exceeding specified intensity thresholds. Graphical and statistical analyses were used to determine how percentages of vulnerable populations varied as the intensity levels and counts of burdens exceeding specified intensity thresholds increased. We found that concentrations of vulnerable populations increase as intensity levels of individual environmental burdens increase and as the number of burdens exceeding specified intensity thresholds increases. In most cases these increases are monotonic and highly statistically significant. Among the five demographic categories examined, the strongest relationships were found for percent people of color, followed by percent with limited English. Weaker but statistically significant relationships were found between other socioeconomic categories and increases in the intensities and counts of environmental burdens. Until recently, nationally consistent data for multiple environmental burdens were not available. Applying the 13 environmental indicators in EJScreen demonstrates that a strong relationship exists between where multiple burdens are simultaneously concentrated and where vulnerable populations reside. That this relationship is stronger for racial/ethnic categories than for other socioeconomic categories reflects outcomes of a history of public policies that have segregated and disadvantaged certain populations in the U.S.