Arsenic in North Carolina: Public Health Implications


Alison P. Sanders1, Kyle P. Messier1, Mina Shehee2, Kenneth Rudo2, Marc L. Serre1, and Rebecca C. Fry1*


1 Department of Environmental Sciences and Engineering, University of North Carolina, Chapel Hill, North Carolina 27599

2 North Carolina Department of Health and Human Services, Raleigh, North Carolina 27699

*rfry at



Arsenic is a known human carcinogen and relevant environmental contaminant in drinking water systems. We set out to comprehensively examine statewide arsenic trends and identify areas of public health concern. Specifically, arsenic trends in North Carolina private wells were evaluated over an eleven-year period using the North Carolina Department of Health and Human Services (NCDHHS) database for private domestic well waters. We geocoded over 63,000 domestic well measurements by applying a novel geocoding algorithm and error validation scheme. Arsenic measurements and geographical coordinates for database entries were mapped using Geographic Information System (GIS) techniques. Furthermore, we employed a Bayesian Maximum Entropy (BME) geostatistical framework, which accounts for geocoding error to better estimate arsenic values across the state and identify trends for unmonitored locations. Of the approximately 63,000 monitored wells, 7,712 showed detectable arsenic concentrations that ranged between 1 and 806 g/L. Additionally, 1,436 well samples exceeded the EPA drinking water standard. We reveal counties of concern and demonstrate a historical pattern of elevated arsenic in some counties, particularly those located along the Carolina terrane (Carolina slate belt). We analyzed these data in the context of populations using private well water and identify counties for targeted monitoring, such as Stanly and Union Counties. By spatiotemporally mapping these data, our BME estimate revealed arsenic trends at unmonitored locations within counties and better predicted well concentrations when compared to the classical kriging method. This study reveals relevant information on the location of arsenic-contaminated private domestic wells in North Carolina and indicates potential areas at increased risk for adverse health outcomes.



Maps of 2009 groundwater Arsenic concentration across North Carolina obtained using methods with increasing estimation accuracy



The Development of these maps was supported by the UNC Superfund Research Program-Research Translation Core (P42-ES005948), with funding from the National Institute of Environmental Health Sciences