Spatiotemporal Estimation of Arsenic in North Carolina Private Wells: Implications for Residents and Migrant Farmworkers

Inorganic arsenic has been found in North Carolina (NC) private wells with especially high concentrations in the state’s south-central region. This highly toxic element poses a health risk to the estimated 3.3 million NC residents who rely on well water. Additionally, NC doesn’t require arsenic testing for migrant farmworkers’ wells putting this population at risk. This project refined previous NC arsenic maps from county to census block group resolutions using Bayesian Maximum Entropy. Truncation distribution imputation, inverse variance weighted averaging, and soft data treatment were validated with a Pearson’s r improvement of 1.39 and reduced temporal fluctuations compared to traditional methods. Migrant farmworkers with the greatest probability of arsenic exposure were then located. Approximately 6,206 workers at 521 locations (iAs >1ppb), 2843 workers at 264 locations (iAs >5ppb) and 2088 workers at 206 locations (iAs >10ppb) exceeded a 10% probability of arsenic exposure at the block group-five-year resolution.