In a climate emergency context, there is a need for continuous water supplies for agricultural activities, mainly in arid and semi-arid regions, where water shortage episodes are more frequent. Reuse of reclaimed water (RW) is a feasible and alternative source to fresh water in agreement with circular economy. However, RW can contain contaminants of emerging concern (CECs) and new transformation products (TPs) that may pose a risk for human health or the environment after their release through agricultural irrigation practices. TPs can show similar or even higher toxicity than parent compounds. However, commercial standards are not always available, hindering a comprehensive evaluation, including toxicity studies. TPs cannot become interesting for standard manufacturing companies if they have not been previously detected in the environment and show high concentrations and/or potential hazardous effects. In consequence, investigation of relevant TPs in environmental compartments is essential.  The present study investigates the occurrence of pharmaceutical TPs in real agricultural systems (water, soil, and fruits) irrigated with RW for more than ten years. A prioritization list containing 20 parent pharmaceuticals, previously identified in the agricultural area under study, was defined based on abundance and detection frequency in the water-soil-plant nexus. A suspect screening strategy was then applied by LC-QTOF-MS in search for potential TPs of the selected compounds. A TP list was built based on TPs already reported in literature and those proposed by using <i>in silico</i> tools (EAWAG-BBD Pathway Prediction System). The final TP list contained 262 TPs. Difficulties in the tentative identification of the TPs included the lack of high-quality MS<sup>2</sup> spectra and the lack of available commercial standards to confirm the proposed structures. Up to 18 TPs could be tentatively identified and 7 of them were confirmed with commercial standards. Finally, an estimation of the toxicity of the identified TPs was carried out using QSAR models.

Investigation of pharmaceutical transformation products in real agricultural crops irrigated with reclaimed water: Current analytical tools and main difficulties

ACS Fall 2021

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