Developing Toxic Metal Environmental Justice Indices (TM-EJIs) for Arsenic, Cadmium, Lead, and Manganese Contamination in Private Drinking Wells in North Carolina

Abstract

Toxic metal exposure via private drinking wells is an environmental health challenge in North Carolina (NC). Policies tainted by environmental racism shape who has access to public water supplies, with Black People, Indigenous People, and People of Color (BIPOC) often excluded from municipal services. Thus, toxic metal exposure via private wells is an environmental justice (EJ) issue, and it is under-studied in NC. In this study, we developed four Toxic Metal Environmental Justice Indices (TM-EJIs) for inorganic arsenic (iAs), cadmium (Cd), lead (Pb), and manganese (Mn) to quantitatively identify areas of environmental injustice in NC. TM-EJIs were calculated at the census tract level (n = 2038) as the product of the following: (1) number of well water tests with concentrations exceeding national standards, (2) percentage of the low-income and minority population, and (3) population density. Mn had the greatest proportion (25.17%) of positive TM-EJIs, which are indicative of socioeconomically disadvantaged groups exposed to toxic metals. Positive TM-EJIs, particularly for Pb and Mn, were primarily located in eastern NC. These results highlight several new counties of concern and can be used by public health professionals and state environmental agencies to prioritize remediation efforts and efforts to reduce environmental injustices.

Geologic predictors of drinking water well contamination in North Carolina

“…North Carolina has been proposed as model area for well water quality in the US [9,10] because it: (1) ranks in the top five states in population using private domestic wells as their drinking water supply [4,11]; (2) has an estimated 40,000-120,000 of people consuming As contaminated drinking water [12][13][14]; (3) has mandatory new well testing and a large water chemistry data set from private wells [13,15]; (4) exhibits significant socioeconomic and racial disparities in access to safe drinking water [10,16]; and (5) presents a diverse aquifer lithology, including volcanic, intrusive, sedimentary, and metamorphic rocks thought to contribute variable amounts of As to groundwater [17]. North Carolina's geology, consisting of Blue Ridge and Piedmont crystalline rock terranes, Coastal Plain sedimentary formations, and minor interior Mesozoic sedimentary basins, is broadly typical of other Eastern US states from Alabama to New York [18].…”