Demographics of dumping. II: A national environmental equity survey and the distribution of hazardous materials handlers

Does the environmental inequality matter? A literature review

The environmental inequality theory reveals that the risk of environmental pollution exposure varies among regions and groups and that particular groups face a higher threat of environmental pollution. In recent years, studies on the environmental inequality issue in developed countries have been increasing, while related literature on developing countries is very scarce. It has been found that some factors, such as race and economic status, have a close relationship with the risk of environmental pollution exposure faced by individuals. For the first time, this paper provides an extensive review of existing theoretical and empirical studies on environmental inequality. We review, in detail, the evolution of the environmental inequality theory, including the definition and measurement of environmental inequality. Further, we provide a systematic refresher on the main performance of environmental inequality, including health, education, labor productivity, and real estate prices. We also identify several causes of environmental inequality, such as ethnic differences, economic status, human capital, and household registration systems. Finally, we discuss prospects for the future research on this issue.

Distribution of environmental justice metrics for exposure to CAFOs in North Carolina, USA

BACKGROUND

Several studies have reported environmental disparities regarding exposure to concentrated animal feeding operations (CAFOs). Public health implications of environmental justice from the intensive livestock industry are of great concern in North Carolina (NC), USA, a state with a large number and extensive history of CAFOs.

OBJECTIVES

We examined disparities by exposure to CAFOs using several environmental justice metrics and considering potentially vulnerable subpopulations.

METHODS

We obtained data on permitted animal facilities from NC Department of Environmental Quality (DEQ). Using ZIP code level variables from the 2010 Census, we evaluated environmental disparities by eight environmental justice metrics (i.e., percentage of Non-Hispanic White, Non-Hispanic Black, or Hispanic; percentage living below the poverty level; median household income; percentage with education less than high school diploma; racial residential isolation (RI) for Non-Hispanic Black; and educational residential isolation (ERI) for population without college degree). We applied two approaches to assign CAFOs exposure for each ZIP code: (1) a count method based on the number of CAFOs within ZIP code; and (2) a buffer method based on the area-weighted number of CAFOs using a 15 km buffer.

RESULTS

Spatial distributions of CAFOs exposure generally showed similar patterns between the two exposure methods. However, some ZIP codes had different estimated CAFOs exposure for the different approaches, with higher exposure when using the buffer method. Our findings indicate that CAFOs are located disproportionately in communities with higher percentage of minorities and in low-income communities. Distributions of environmental justice metrics generally showed similar patterns for both exposure methods, however starker disparities were observed using a buffer method.

CONCLUSIONS

Our findings of the disproportionate location of CAFOs provide evidence of environmental disparities with respect to race and socioeconomic status in NC and have implications for future studies of environmental and health impacts of CAFOs.

Modelling collinear and spatially correlated data

In this work we present a statistical approach to distinguish and interpret the complex relationship between several predictors and a response variable at the small area level, in the presence of (i) high correlation between the predictors and (ii) spatial correlation for the response. Covariates which are highly correlated create collinearity problems when used in a standard multiple regression model. Many methods have been proposed in the literature to address this issue. A very common approach is to create an index which aggregates all the highly correlated variables of interest. For example, it is well known that there is a relationship between social deprivation measured through the Multiple Deprivation Index (IMD) and air pollution; this index is then used as a confounder in assessing the effect of air pollution on health outcomes (e.g. respiratory hospital admissions or mortality). However it would be more informative to look specifically at each domain of the IMD and at its relationship with air pollution to better understand its role as a confounder in the epidemiological analyses. In this paper we illustrate how the complex relationships between the domains of IMD and air pollution can be deconstructed and analysed using profile regression, a Bayesian non-parametric model for clustering responses and covariates simultaneously. Moreover, we include an intrinsic spatial conditional autoregressive (ICAR) term to account for the spatial correlation of the response variable.

Race/ethnicity, residential segregation, and exposure to ambient air pollution: the Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVES

We described the associations of ambient air pollution exposure with race/ethnicity and racial residential segregation.

METHODS

We studied 5921 White, Black, Hispanic, and Chinese adults across 6 US cities between 2000 and 2002. Household-level fine particulate matter (PM2.5) and nitrogen oxides (NOX) were estimated for 2000. Neighborhood racial composition and residential segregation were estimated using US census tract data for 2000.

RESULTS

Participants in neighborhoods with more than 60% Hispanic populations were exposed to 8% higher PM2.5 and 31% higher NOX concentrations compared with those in neighborhoods with less than 25% Hispanic populations. Participants in neighborhoods with more than 60% White populations were exposed to 5% lower PM2.5 and 18% lower NOX concentrations compared with those in neighborhoods with less than 25% of the population identifying as White. Neighborhoods with Whites underrepresented or with Hispanics overrepresented were exposed to higher PM2.5 and NOX concentrations. No differences were observed for other racial/ethnic groups.

CONCLUSIONS

Living in majority White neighborhoods was associated with lower air pollution exposures, and living in majority Hispanic neighborhoods was associated with higher air pollution exposures. This new information highlighted the importance of measuring neighborhood-level segregation in the environmental justice literature.

Distributional benefit analysis of a national air quality rule

Under Executive Order 12898, the U.S. Environmental Protection Agency (EPA) must perform environmental justice (EJ) reviews of its rules and regulations. EJ analyses address the hypothesis that environmental disamenities are experienced disproportionately by poor and/or minority subgroups. Such analyses typically use communities as the unit of analysis. While community-based approaches make sense when considering where polluting sources locate, they are less appropriate for national air quality rules affecting many sources and pollutants that can travel thousands of miles. We compare exposures and health risks of EJ-identified individuals rather than communities to analyze EPA's Heavy Duty Diesel (HDD) rule as an example national air quality rule. Air pollutant exposures are estimated within grid cells by air quality models; all individuals in the same grid cell are assigned the same exposure. Using an inequality index, we find that inequality within racial/ethnic subgroups far outweighs inequality between them. We find, moreover, that the HDD rule leaves between-subgroup inequality essentially unchanged. Changes in health risks depend also on subgroups' baseline incidence rates, which differ across subgroups. Thus, health risk reductions may not follow the same pattern as reductions in exposure. These results are likely representative of other national air quality rules as well.

Environmental justice: a contrary finding for the case of high-voltage electric power transmission lines

Environmental justice is the consideration of whether minority and/or lower-income residents in a geographic area are likely to have disproportionately higher exposures to environmental toxins than those living elsewhere. Such situations have been identified for a variety of factors, such as air pollution, hazardous waste, water quality, noise, residential crowding, and housing quality. This study investigates the application of this concept to high-voltage electric power transmission lines (HVTL), which some perceive as a health risk because of the magnetic fields they generate, and also as esthetically unpleasing. We mapped all 345 kV and higher voltage HVTL in New York State and extracted and summarized proximate US Census sociodemographic and housing characteristic data into four categories on the basis of distances from HVTL. Contrary to our expectation, people living within 2000 ft from HVTL were more likely to be exposed to magnetic fields, white, of higher income, more educated and home owners, than those living farther away, particularly in urban areas. Possible explanations for these patterns include the desire for the open space created by the rights-of-way, the preference for new homes/subdivisions that are often located near HVTL, and moving closer to HVTL before EMFs were considered a risk. This study suggests that environmental justice may not apply to all environmental risk factors and that one must be cautious in generalizing. In addition, it shows the utility of geographical information system methodology for summarizing information from extremely large populations, often a challenge in epidemiology.

Social disparities in health: disproportionate toxicity proximity in minority communities over a decade

This study employs latent trajectory models measuring the level of toxic waste over a decade in the cities of six highly populated, ethnically diverse, counties in southern California from 1990 to 2000 in 3001 tracts. We find that tracts with 15% more Latinos are exposed to 84.3% more toxic waste than an average tract over this time period and tracts with 15% more Asians are exposed to 33.7% more toxic waste. Conversely, tracts with one standard deviation more residents with at least a bachelor's degree (15.5%) are exposed to 88.8% less toxic waste than an average tract. We also found that these effects were considerably weaker when using the raw pounds of toxic waste rather than the toxicity-weighted measure, suggesting that future research will want to account for the toxicity of the waste.

Racial and socioeconomic disparities in residential proximity to polluting industrial facilities: evidence from the Americans' Changing Lives Study

OBJECTIVES

We sought to demonstrate the advantages of using individual-level survey data in quantitative environmental justice analyses and to provide new evidence regarding racial and socioeconomic disparities in the distribution of polluting industrial facilities.

METHODS

Addresses of respondents in the baseline sample of the Americans' Changing Lives Study and polluting industrial facilities in the Environmental Protection Agency's Toxic Release Inventory were geocoded, allowing assessments of distances between respondents' homes and polluting facilities. The associations between race and other sociodemographic characteristics and living within 1 mile (1.6 km) of a polluting facility were estimated via logistic regression.

RESULTS

Blacks and respondents at lower educational levels and, to a lesser degree, lower income levels were significantly more likely to live within a mile of a polluting facility. Racial disparities were especially pronounced in metropolitan areas of the Midwest and West and in suburban areas of the South.

CONCLUSIONS

Our results add to the historical record demonstrating significant disparities in exposures to environmental hazards in the US population and provide a paradigm for studying changes over time in links to health.

Superfund, hedonics, and the scales of environmental justice

Environmental justice (EJ) is prominent in environmental policy, yet EJ research is plagued by debates over methodological procedures. A well-established economic approach, the hedonic price method, can offer guidance on one contentious aspect of EJ research: the choice of the spatial unit of analysis. Environmental managers charged with preventing or remedying inequities grapple with these framing problems. This article reviews the theoretical and empirical literature on unit choice in EJ, as well as research employing hedonic pricing to assess the spatial extent of hazardous waste site impacts. The insights from hedonics are demonstrated in a series of EJ analyses for a national inventory of Superfund sites. First, as evidence of injustice exhibits substantial sensitivity to the choice of spatial unit, hedonics suggests some units conform better to Superfund impacts than others. Second, hedonic estimates for a particular site can inform the design of appropriate tests of environmental inequity for that site. Implications for policymakers and practitioners of EJ analyses are discussed.

A spatial evaluation of socio demographics surrounding National Priorities List sites in Florida using a distance-based approach

BACKGROUND

Over the last two decades, various spatial techniques have been demonstrated using geographical information systems (GIS) to adequately estimate and characterize inequities of minority populations living near environmentally hazardous facilities. However, these methods have produced mixed results. In this study, we use recently developed variations of the "distance based" approach to spatially evaluate and compare demographic and socioeconomic disparities surrounding the worst hazardous waste sites in Florida.

METHODS

We used data from the 2000 US Census Bureau and the Florida Department of Environmental Protection to identify selected socio and economic variables within one (1) mile of 71 National Priorities List (NPL) or Superfund sites in Florida. ArcMap (ESRI, v. 9.2) was used to map the centroid locations of each of the NPL sites as well as identify and estimate the number of host and non-host tracts. The unit of analysis in this study was at the census tract level. Logistic regression (SAS v9.1.3) was used to determine if race/ethnicity and socioeconomic indicators are significant predictors of the location of NPL sites.

RESULTS

There were significant differences in race/ethnicity composition and socio-economic factors between NPL host census tracts and non-host census tracts in Florida. The percentages of Blacks (OR = 5.7, p < 0.001), the percentage of Hispanic/Latino (OR = 5.84, p < 0.001), and percent employed in blue collar occupations (OR = 2.7, p < 0.01) were significant predictors of location of NPL facilities.

CONCLUSION

The recently developed distance-based method supports previous studies and suggests that race and ethnicity play substantial roles in where hazardous facilities are located in Florida. Recommendations include using distance-based methods to evaluate socio and demographic characteristics surrounding other less known environmental hazardous facilities, such as landfills, or Toxic Release Inventory (TRI) sites.

Environmental inequity in England: small area associations between socio-economic status and environmental pollution

Recent studies have suggested that more deprived people tend to live in areas characterised by higher levels of environmental pollution. If generally true, these environmental inequities may combine to cause adverse effects on health and also exacerbate problems of confounding in epidemiological studies. Previous studies of environmental inequity have nevertheless indicated considerable complexity in the associations involved, which merit further investigation using more detailed data and more advanced analytical methods. This study investigates the ways in which environmental inequity in England varies in relation to: (a) different environmental pollutants (measured in different ways); (b) different aspects of socio-economic status; and (c) different geographical scales and contexts (urban vs. rural). Associations were analysed between the Index of Multiple Deprivation (IMD2004) and its domains and five sets of environmental pollutants (relating to road traffic, industry, electro-magnetic frequency radiation, disinfection by-products in drinking water and radon), measured in terms of proximity, emission intensity and environmental concentration. Associations were assessed using bivariate and multivariate correlation, and by comparing the highest and lowest quintiles of deprivation using Student's t-test and Hotelling's T2. Associations are generally weak (R(2) < 0.10), and vary depending on the specific measures used. Strongest associations occur with what can be regarded as contingent components of deprivation (e.g. crime, living environment, health) rather than causative factors such as income, employment or education. Associations also become stronger with increasing level of spatial aggregation. Overall, the results suggest that any triple jeopardy for health, and problems of confounding, associated with environmental inequities are likely to be limited.

Skewed riskscapes and environmental injustice: a case study of metropolitan St. Louis

This article presents a case study of Toxics Release Inventory (TRI) air pollution exposure risks across metropolitan St. Louis. The first section critically reviews environmental justice research and related barriers to environmental risk management. Second, the paper offers a conventional analysis of the spatial patterns of TRI facilities and their surrounding census block group demographics for metropolitan St. Louis. Third, the article describes the use of an exposure risk characterization for 319 manufacturers and their air releases of more than 126 toxic pollutants. This information could lead to more practical resolutions of urban environmental injustices. The analysis of TRIs across metropolitan St. Louis shows that minority and low-income residents were disproportionately closer to industrial pollution sources at nonrandom significance levels. Spatial concentrations of minority residents averaged nearly 40% within one kilometer of St. Louis TRI sites compared to 25% elsewhere. However, one-fifth of the region's air pollution exposure risk over a decade was spatially concentrated among only six facilities on the southwestern border of East St. Louis. This disproportionate concentration of some of the greatest pollution risk would never be considered in most conventional environmental justice analyses. Not all pollution exposure risk is average, and the worst risks deserve more attention from environmental managers assessing and mitigating environmental injustices.

Reassessing racial and socioeconomic disparities in environmental justice research

The number of studies examining racial and socioeconomic disparities in the geographic distribution of environmental hazards and locally unwanted land uses has grown considerably over the past decade. Most studies have found statistically significant racial and socioeconomic disparities associated with hazardous sites. However there is considerable variation in the magnitude of racial and socioeconomic disparities found; indeed, some studies have found none. Uncertainties also exist about the underlying causes of the disparities. Many of these uncertainties can be attributed to the failure of the most widely used method for assessing environmental disparities to adequately account for proximity between the hazard under investigation and nearby residential populations. In this article, we identify the reasons for and consequences of this failure and demonstrate ways of overcoming these shortcomings by using alternate, distance-based methods. Through the application of such methods, we show how assessments about the magnitude and causes of racial and socioeconomic disparities in the distribution of hazardous sites are changed. In addition to research on environmental inequality, we discuss how distance-based methods can be usefully applied to other areas of demographic research that explore the effects of neighborhood context on a range of social outcomes.

Future directions in residential segregation and health research: a multilevel approach

The authors examine the research evidence on the effect of residential segregation on health, identify research gaps, and propose new research directions. Four recommendations are made on the basis of a review of the sociological and social epidemiology literature on residential segregation: (1) develop multilevel research designs to examine the effects of individual, neighborhood, and metropolitan-area factors on health outcomes; (2) continue examining the health effects of residential segregation among African Americans but also initiate studies examining segregation among Hispanics and Asians; (3) consider racial/ethnic segregation along with income segregation and other metropolitan area factors such as poverty concentration and metropolitan governance fragmentation; and (4) develop better conceptual frameworks of the pathways that may link various segregation dimensions to specific health outcomes.