Uptake of emerging contaminants in tomato plants: a field study on treated wastewater reuse

Reusing treated wastewater (TWW) for agricultural irrigation offers a sustainable option to reduce water scarcity; however, it also raises concerns about potential contamination of the food chain. This study evaluated the uptake and translocation of 27 contaminants of emerging concern (CECs) in tomatoes grown under field conditions. The experiment consisted of four drip irrigation regimes: (1) potable water (PW), (2) TWW, (3) PW with addition of CECs (1 mg/L), and (4) TWW with addition of CECs (1 mg/L). Results show that CECs were less stable in TWW than in PW, influencing their uptake. Tomato fruits also showed minimal bioaccumulation under non-spiked conditions, with only carbamazepine above LOQ when irrigated with TWW (22 ng/g). In spiked media, acetamiprid, azithromycin, bisphenol S, carbamazepine, clarithromycin, and dimethomorph were above LOQ in tomato fruits, while up to 17 CECs were quantified in roots > leaves > stems. Fruit yield also remained unaffected. Dietary exposure estimates were below the risk threshold for tomatoes irrigated with TWW. Soil analysis revealed CECs (azithromycin, triclocarban) exceeding safety thresholds up to 30 months after irrigation. In summary, while targeted CECs in tomato fruits pose no immediate health risk, their accumulation in soil highlights the need for long-term monitoring.