摘要：We sought to provide a historical overview of methods, models, and data used in the environmental justice (EJ) research literature to measure proximity to environmental hazards and potential exposure to their adverse health effects. We explored how the assessment of disproportionate proximity and exposure has evolved from comparing the prevalence of minority or low-income residents in geographic entities hosting pollution sources and discrete buffer zones to more refined techniques that use continuous distances, pollutant fate-and-transport models, and estimates of health risk from toxic exposure. We also reviewed analytical techniques used to determine the characteristics of people residing in areas potentially exposed to environmental hazards and emerging geostatistical techniques that are more appropriate for EJ analysis than conventional statistical methods. We concluded by providing several recommendations regarding future research and data needs for EJ assessment that would lead to more reliable results and policy solutions. ENVIRONMENTAL JUSTICE (EJ) is defined broadly as the disproportionate distribution of environmental “goods” and “bads,” with the burden of the bads and the dearth of the goods falling mainly on racial and ethnic minorities, lower income populations, and other vulnerable groups. Since the 1980s, a large body of literature on EJ has emerged, mainly focused on areas in the United States and often using geographic information systems (GIS) to assess the proximity of vulnerable subpopulations to environmental hazards as a proxy for exposure and the potential for deleterious health impacts. 1 – 11 GIS technology is well suited to EJ research because it allows for the integration of multiple data sources, cartographic representation of data, and the application of various spatial analytical techniques for proximity analysis. 11 , 12 Although maps are effective in visually demonstrating the disproportionate spatial distribution of environmental hazards, researchers have commented on the challenges and limitations inherent in spatial analysis and questioned GIS's efficacy in demonstrating pollution's health impacts. Spatial and attribute data deficiencies and methodological problems, especially those related to geographical considerations, have been well documented. 6 , 11 , 13 – 23 However, development of methods for producing more meaningful spatial analyses is feasible, and health geographers and other researchers have been using GIS to demonstrate the correspondence among factors such as proximity to hazards, disproportionate exposure, and health disparities. We reviewed methods commonly used by EJ researchers in articles that were selected to provide a comprehensive overview and synopsis of quantitative research on EJ and disproportionate proximity to environmental hazards over the past 2 decades. We searched these databases for relevant published literature: Sociological Abstracts, Social Science Citation Index, Science Citation Index, and the National Library of Medicine's PubMed. We initially selected studies by using the search terms environmental justice, environmental equity, and environmental racism. We attempted to find studies exhibiting as wide a range as possible in terms of geographic extent studied, variety of hazards examined, and analytical techniques used. We excluded literature review articles and those using purely theoretical or qualitative approaches. The final list of references selected for our critical review of EJ research methodology consisted of quantitative case studies (n = 80) that examined racial–ethnic and socioeconomic disparities in the distribution of, or proximity to, environmental health risks, pollution sources, and undesirable land uses. Most of these studies indicated a disproportionate distribution of environmental burdens with respect to both race and socioeconomic status (SES). Although SES variables pointed to more significant risks of exposure than race, 17 , 24 – 27 race tended to be significant even when controlling for SES. 28 – 31 We summarized the most frequently cited and significant studies (n = 55) reviewed in Online Supplemental Table 1 (available at www.ajph.org), which includes the study parameters and scope, pollution indicators used, methodology used, and findings. We provide a historical overview and critical assessment of (1) analytical approaches used to spatially define the boundaries of areas potentially exposed to environmental hazards, (2) methods for estimating population characteristics of such areas, and (3) emerging geostatistical techniques that address limitations of conventional approaches.
