Does ketoprofen or diclofenac pose the lowest risk to fish?

► Ketoprofen bioconcentrates poorly (<0.05) from water to trout blood plasma. ► No pharmacological responses were identified by microarray or qPCR at 100 μg/L. ► Based on single drug exposure data, ketoprofen is less likely to affect wild fish. ► Bioconcentration factors for NSAIDs were much higher in effluent-exposed fish. ► Single drug exposures may underestimate field bioconcentration and thus risks.