Soil accumulation and plant uptake of pharmaceutical active compounds and related metabolites from irrigation water in fennel (Foeniculum vulgare Mill.)

Introduction: The reuse of treated wastewater (TWW) in agriculture is attracting increasing interest as a sustainable strategy to address water scarcity, particularly in arid and semi-arid regions. However, its use can pose risks due to the potential presence of emerging contaminants of concern, such as personal care products and pharmaceuticals. Methods: This study investigated the fate of three commonly occurring pharmaceutical contaminants (PhACs) (carbamazepine, climbazole, and flecainide) and their metabolites in the soil–plant system when applied through treated wastewater. The research involved irrigating a fennel crop (Foeniculum vulgare Mill.) with fresh water spiked with these PhACs at different concentrations (0.5, 2.0, 200, and 600 µg L⁻¹). Fennel plants were grown under controlled greenhouse conditions and analysed for PhAC content in their roots, leaves, and edible parts (bulbs). Soil and plant PhACs content were evaluated using SPE-UHPLC-HRMS/MS and the Bioconcentration (BCF) and translocation factors (TF) were also assessed. Results: Results showed PhACs accumulation in the soil and roots only at higher spiked concentrations (≥200 µg L⁻¹). Among the compounds, carbamazepine exhibited the highest root accumulation (BCF>1), but limited translocation to bulbs (TF<1). Climbazole and flecainide, despite their persistence in soil, showed low root uptake (BCF<1) and negligible translocation to bulbs. Discussion: Multivariate statistical analyses revealed compound-specific patterns governed by physicochemical properties such as ionization and hydrophobicity. Overall, fennel crop showed a restricted capacity to accumulate and translocate PhACs to bulbs, suggesting a physiological barrier that may reduce human health risks when using treated wastewater for irrigation. The results provide new insights into the environmental safety of wastewater reuse, with a specific focus on its impact on crop yield, highlighting the need for crop-specific assessments.