Study Points to Environmental Injustice as Contributor to Health Disparities in US

In the United States, areas with greater environmental injustice are linked with increased levels of poor or fair health affecting a high amount of Black and Hispanic residents, according to a recent study published in JAMA Internal Medicine.¹

Investigators attributed this disparity to decades of underinvestment which exposed these communities to hazardous environmental conditions, though the impact of these exposures hasn’t been quantified.

The cross-sectional study used Census-tract level data measured by the Environmental Justice Index (EJI), a novel measurement developed by the CDC, which offers a localized assessment of combined environmental and social burdens at a national scale. Leveraging the EJI, investigators assessed the correlation between environmental injustices and self-reported health conditions at the neighborhood level.²

The team, led by Vishal R. Patel, BS, Dell Medical School, The University of Texas at Austin, sought to pinpoint the environmental stressors linked with fluctuations in self-reported health outcomes.¹

Areas with greater environmental injustice are linked with increased levels of poor or fair health affecting a high amount of Black and Hispanic residents, a new study found.

The study focused on neighborhoods across the United States in 2020 with the primary objective of evaluating the potential relationship between environmental justice and the health status of these neighborhoods. To achieve this, environmental injustice, a critical variable in the study, was quantified through the EJI, which assigned scores ranging from 0 to 1 to different neighborhoods.

Higher EJI scores indicated elevated levels of exposure to environmental factors and societal vulnerabilities that could potentially influence health outcomes. The study noted the EJI primarily encompasses distributive and procedural environmental justice elements, providing a somewhat approximate representation of factors related to health-relevant physical exposures. However, the index does not directly address individual-level risks.

The primary health outcome was the prevalence of self-reported poor or fair health. To further refine the analysis, neighborhoods with a substantial proportion of minority residents were specifically identified by investigators. This identification was based on the top decile classification of Census tracts or those with the highest proportions of Black and Hispanic residents.

Risk-adjusted prevalence of poor or fair health was estimated with a mixed-effects beta regression model consisting of age, sex, population, size, measures of health care access, metropolitan status, county random effects, and a high proportion minority neighborhood interaction item measured by the EJI. To determine the relative importance of each environmental burden captured, investigators used a dominance analysis where a 2-sided P < .05 was noted as significant.

The analysis included a total of 71,669 neighborhoods, representing 98.1% coverage of all conterminous neighborhoods in the United States. Among these, a subset consisting of 7211 neighborhoods demonstrated a high proportion of minority residents.

Of the minority neighborhoods, 33% were positioned in the top quintile of the EJI, signifying higher cumulative exposure to environmental and social burdens, according to the study. In contrast, 0.5% of these neighborhoods fell into the bottom quintile, indicating lower levels of such burdens.

Results revealed a clear association between the degree of environmental injustice in a neighborhood and the prevalence of self-reported poor or fair health. Findings from the adjusted analyses exemplified a pattern.

The strength of this association differed significantly based on the racial composition of the neighborhoods. Specifically, neighborhoods with a high proportion of minority residents exhibited a heightened prevalence of poor or fair health in regions characterized by elevated EJI scores.

The interaction was statistically significant (P < .001), highlighting the intricate interplay between environmental injustice, racial concentration, and health outcomes.

In neighborhoods with a substantial minority population, health status variations were notably associated with exposure to air pollution contributing 30% to the effect, and the presence of potentially toxic and hazardous sites contributing 31% to the effect. Although, in neighborhoods with different demographic compositions, health status variations were predominantly linked with factors of the built environment which accounted for a substantial 66% of the effect.

The study stated the results emphasize disparities in the sources of health variations within different types of neighborhoods and the specific factors that could be targeted to address these discrepancies effectively.

References

1. Patel VR, Jella T, Gupta A, Nassel A, Ibrahim A, Hussaini SQ. Association of Neighborhood-Level Environmental Injustice With Health Status in the US. JAMA Intern Med. Published online August 14, 2023. doi:10.1001/jamainternmed.2023.2835

2. Environmental Justice Index. Agency for Toxic Substances and Disease Registry. Last Reviewed July 20, 2023. Accessed August 21, 2023. https://www.atsdr.cdc.gov/placeandhealth/eji/index.html