Influence of time-dependent sampling on fish plasma levels of select pharmaceuticals and per- and polyfluoroalkyl substances (PFASs)

Determining pharmaceutical levels in fish plasma represents an increasingly valuable approach for environ-mental assessments of pharmaceuticals. These fish plasma observations are compared to human therapeutic plasma doses because of the high evolutionary conservation of many drug targets among vertebrates. In the present study, we initially identified highly variable information regarding plasma sampling practices in the literature and then tested the hypothesis that fish plasma levels of selected pharmaceuticals and per-and pol-yfluoroalkyl substances (PFASs) would not change with time to process samples from the field. After common carp were placed in a wastewater-fed pond for one month, we immediately sampled fish plasma nonlethally in the field or after transferring fish to clean water and held them under these conditions for either 3 or 20 h. We then quantitated pharmaceuticals in water, and pharmaceuticals and PFASs in plasma by LC-MSMS. Whereas plasma levels of most pharmaceuticals decreased even after 3 h that fish spent in clean water, plasma concen-trations of the PFASs examined here remained stable over 20 h. Collectively, our examination of these time -dependent sampling approaches and associated findings highlight the importance of appropriate and consis-tent sampling for bioaccumulation studies, biomonitoring activities, and aquaculture product safety evaluations.