Soil constitutes a major sink for microplastics (MPs). In agricultural soils, microplastics co-occur with pesticides and veterinary medicines like anthelminthics (AHs). Little is known regarding the influence of microplastics on the dissipation of these organic pollutants. We hypothesized (a) that microplastics due to their hydrophobic surfaces would affect the dissipation of the anthelminthic albendazole (ABZ) and the fungicide pyraclostrobin (PYR), and (b) the outcome of this interaction will vary depending on the type (PBAT-based, Starch-based, and LDPE-based) and the concentration (0.1 and 0.01%) of plastics. (c) Besides microplastics, the co-occurrence of ABZ and PYR will influence each other’s dissipation. We tested the dissipation of ABZ and PYR in the presence and absence of microplastics in three soils. The dissipation of ABZ was accelerated in the presence of microplastics in Greek soil (DT50 2.8–8.2 days vs 13.9 days in the control) but not in the other two soils, while microplastics had no effect on the dissipation of PYR in all three soils. No systematic type- or concentration-driven effect of microplastics on ABZ and PYR soil dissipation was observed in the three soils. Regardless of microplastics’ presence, ABZ delayed PYR dissipation in Greek soil (DT50 47.5 to 99.4 days), an effect further exacerbated in the presence of microplastics (DT50 47.0–59.9 to 72.1–117.5 days). We suggest that complex tripartite interactions between pesticides–anthelminthics–microplastics are operative in agricultural soils affecting the dissipation of pesticides and anthelminthics. These interactions are not considered in the current framework of chemical risk assessment, and they are expected to have serious implications, undermining environmental quality and soil health.
