Multiscale Analysis of the Relationship between Toxic Chemical Hazard Risks and Racial/Ethnic and Socioeconomic Groups in Texas, USA

Extreme rainfall disproportionately impacts E. coli concentrations in Texas recreational waterbodies

Waterborne pathogen contamination poses a significant threat to water resources globally and the exposure to waterborne pathogen contamination is widely recognized as unevenly distributed. Extreme weather events could exacerbate inequalities in waterborne disease as climate variability continues to escalate. However, there is a limited understanding of how extreme rainfall affects E. coli levels and whether disadvantaged communities experience disproportionate impacts from extreme rainfall on E. coli contamination. Leveraging 21 years of E. coli data along with climate data and watershed characteristics, this study employed Multiscale Geographically Weighted Regression (MGWR) models to quantify the seasonal and spatial impacts of extreme rainfall on E. coli concentrations in Texas. Our results indicate that during dry seasons, regions in northern and eastern Texas exhibit significantly higher impacts of extreme rainfall on E. coli concentrations, which is associated with high proportions of pastures, wetlands, and silt. However, during wet seasons, western and southern regions experience slightly higher extreme rainfall induced E. coli contamination risks likely due to significantly increased runoff from the rainfall together with higher slopes and clay-rich soil. In addition, we found census tracts with higher proportions of Black and Latino populations experience greater extreme rainfall impacts on E. coli levels in different months. Furthermore, an analysis of historical trends in extreme rainfall intensity indicates that climate variability could further amplify the existing inequalities in exposure to E. coli contamination. Our findings highlight the disproportionate impacts of extreme rainfall induced E. coli contamination on disadvantaged communities and emphasize the critical need for targeted intervention strategies to mitigate these risks effectively and equitably in Texas.

Environmental justice of Texas recreational water quality - The disproportionate E. coli levels and trends

The presence of pathogens is one of the leading causes of stream water quality impairment in the US. Escherichia coli (E. coli) is a fecal pathogen indicator and also signals the presence of more pathogenic microbes. Although it is reported that Black, Indigenous, and communities of color suffer more from E. coli contamination, there is a lack of investigation of the potential inequality of E. coli contamination in recreational waterbodies, particularly regarding whether this inequality persists over the long term. Using E. coli monitoring data from 1,424 stations from 2001 to 2021 in Texas, we tested the research hypotheses of racial and economic inequalities in E. coli levels and trends with quantile regression and logistic regression approaches. We found that economic disparities had a more significant relationship with E. coli contamination in Texas recreational waterbodies than racial disparities after controlling for building age, land covers, imperviousness, and precipitation. The economic disparities in E. coli contamination were more prevalent after 2010 and in extreme E. coli levels. In addition, implementing watershed protection plans could mitigate the economic disparities associated with the rising trend of E. coli levels between 2001 and 2021. Findings from this research underscore clean surface water deprivation from underserved communities and call for inclusive watershed management strategies to address the water quality injustice.

Historical Redlining Is Associated with Disparities in Environmental Quality across California

Historical policies have been shown to underpin environmental quality. In the 1930s, the federal Home Owners' Loan Corporation (HOLC) developed the most comprehensive archive of neighborhoods that would have been redlined by local lenders and the Federal Housing Administration, often applying racist criteria. Our study explored how redlining is associated with environmental quality across eight California cities. We integrated HOLC's graded maps [grades A (i.e., "best" and "greenlined"), B, C, and D (i.e., "hazardous" and "redlined")] with 10 environmental hazards using data from 2018 to 2021 to quantify the spatial overlap among redlined neighborhoods and environmental hazards. We found that formerly redlined neighborhoods have poorer environmental quality relative to those of other HOLC grades via higher pollution, more noise, less vegetation, and elevated temperatures. Additionally, we found that intraurban disparities were consistently worse for formerly redlined neighborhoods across environmental hazards, with redlined neighborhoods having higher pollution burdens (77% of redlined neighborhoods vs 18% of greenlined neighborhoods), more noise (72% vs 18%), less vegetation (86% vs 12%), and elevated temperature (72% vs 20%), than their respective city's average. Our findings highlight that redlining, a policy abolished in 1968, remains an environmental justice concern by shaping the environmental quality of Californian urban neighborhoods.