The oral bioaccessibility of potentially toxic elements of illegal landfills’ soil and health risk assessment for field workers

Based on their adverse impact on the environment and human health, landfills represent one of the biggest environmental issues. In this study, the soil samples (two depths, 0-30 and 30-60 cm) from 6 illegal landfills located in the agricultural areas in the Autonomous Vojvodina (AP) Province in Serbia were investigated to assess the bioaccessibility of potentially toxic elements (PTEs: As, Cd, Co, Cr, Cu, Ni, Pb, and Zn) and health risk for field workers. All PTEs, except Pb, in some of the studied soils exceeded the threshold value (TV) prescribed by the national regulation. To assess their bioaccessibility, in vitro gastrointestinal test, the Unified BARGE Method (UBM), was used. The UBM test simulates the three phases of the gastrointestinal tract: saliva (S), gastric (GE), and intestinal (IE) by the appropriate fluids. For most of the analyzed PTEs, higher concentrations were extracted in the gastric (GE) phase due to the acidity of the fluid. The bioaccessibility of the investigated PTEs does not exceed 50%, and the highest bioaccessibility from the soil was observed for Cu (40.54%). The workers' health risk assessment (WHRA) indicated no high risk (HI < 1) for developing non-carcinogenic illness for workers in agricultural fields, while there was moderate carcinogenic risk based on both pseudo-total (R = 2.60 × 10^-5) and bioaccessible (R = 1.58 × 10^-6) concentrations. The highest influence on the workers' health has oral exposure to the soil (HI_o: 8.82 × 10^-2 > HI_d: 9.24 × 10^-3 > HI_i: 1.09 × 10^-3; R_o: 1.89 × 10^-5 > R_d: 6.97 × 10^-6 > R_i: 3.86 × 10^-8). Utilizing Both scenarios, the worst-case scenario and the "more realistic" based on bioaccessible concentrations, showed that exposure of the field workers to these soil samples has adverse effects on their health.