Drinking water disparities and aluminum concentrations: Assessing socio-spatial dimensions across an urban landscape

Abstract

The United States Environmental Protection Agency does not enforce a maximum contaminant level of Aluminum (Al) in treated drinking water and trace amounts are commonly found in household tap water. Al is known to impact the aesthetics of tap water, and research shows that exposure may have adverse impacts on human health. Socioeconomic status (SES) may play a role in Al exposure since some water treatment plants utilize “Alum” as an affordable treatment method, even though higher Al concentrations can result in finished drinking water. The objective of this study is to identify socio-spatial variations in concentrations of Al in household tap water across a highly diverse urban landscape. A total of 96 households in eastern Palm Beach County, Florida were randomly selected and tap water samples were collected from an unfiltered faucet and tested for Al. Al was above method detection limit in 56% of the samples analyzed, and 6% of the samples were above Florida’s secondary maximum contaminant level (concentrations ranged from 0.009 mg/L - 0.429 mg/L). Significant spatial clusters of higher Al concentrations in areas of lower SES were identified using local spatial autocorrelation (Getis-Ord Gi*). Maximum Likelihood of Spatial Lag and Spatial Weighted Least Squares HET regression models confirm a significant association between higher Al concentrations in tap water and lower SES. The findings of this study may be useful to water officials who aim to reduce levels of Al in tap water by prioritizing communities that experience the greatest socioeconomic deprivation.