Fate of dissolved pharmaceutically active compounds (PhACs) in irrigation water in rice paddy: Implications to human and soil health.

Pharmaceutically active compounds (PhACs) may enter the food chain through food crops. This study investigates the influence of dissolved PhACs in irrigation water on rice crops and soil, identifying enduring implications on human and soil health. We conducted a field-scale experiment to investigate the accumulation and impacts of two prevalent PhACs, ibuprofen (IBP) and caffeine (CAF), in irrigation water on rice paddies under realistic agronomic conditions. The experiment was carried out in designated subplots with three dosage levels. The results revealed that IBP exhibited higher persistence in the field soil, leading to ∼2 times higher plant uptake than CAF. Most of the introduced contaminants attenuated in soil,root, shoot or degraded naturally, reducing grain accumulation, which ranged from 0.13% to 0.4% and from 0.38% to 1.4% for IBP and CAF, respectively. However, toxic PhAc metabolites were identified in the grains, raising significant concerns. Owing to its higher translocation and grain accumulation, the hazard quotient (HQ) of CAF surpassed 0.1, indicating a potential risk associated with regular dietary intake. The presence of PhACs significantly altered soil microbial enzyme activities, bacterial abundance, and community composition within the soil-plant microbiome, indicating potential long-term impacts on geo-health. In conclusion, the applied PhACs undergo significant attenuation within the field-soil and plant components, lowering grain accumulation; however, the presence of toxic PhAC metabolites in grains and changes in soil bacterial composition indicate potential concerns.