Hidden toxicities: assessing city-wide contamination by potentially toxic elements from illegal dumping in Jackson, Mississippi

Abstract Illegal dumping is widespread where waste collection is unreliable, and municipal responses usually end with removal of visible waste, leaving the underlying soil unexamined. We asked whether elemental enrichment persists below the surface once waste is cleared, whether lithogenic and waste-derived contributions can be separated using field-portable screening alone, and whether a low-cost protocol can prioritize sites in a city without laboratory capacity. At 45 community-reported dumping sites across Jackson, Mississippi, we measured eight potentially toxic elements (the metalloid arsenic with cadmium, chromium, copper, manganese, nickel, lead and zinc) in composite soils at 0 to 2.5 cm and 15 cm by portable X-ray fluorescence, with laboratory ICP-OES on a 13-site subset for independent method comparison. Lead, copper and zinc dominated enrichment and co-occurred, and concentrations at 15 cm approached surface values, indicating the elemental burden is not lifted when surface waste is removed. Principal component and cluster analyses, corroborated by partial-extraction recoveries, separated a chromium, nickel and iron association consistent with lithogenic sources from a zinc, arsenic and lead association consistent with waste inputs. Distributions were strongly right-skewed, so ward means reflect a few extreme sites. A screening-level risk assessment gave hazard indices above unity at 21 of 45 sites for a child resident, driven largely by geogenic arsenic and manganese, whereas lead, the clearest waste-derived element, exceeded the United States Environmental Protection Agency residential soil screening level at 11 sites. Field screening with selective laboratory confirmation offers resource-limited cities a practical route to prioritize remediation.