Bioaccumulation and trophodynamics of the antidepressants sertraline and fluoxetine in laboratory-constructed, 3-level aquatic food chains

Although reports of pharmaceutical bioconcentration in aquatic organisms are increasing, less is known about trophic transfer in aquatic food webs. The bioaccumulation and trophodynamics of sertraline and fluoxetine, 2 selective serotonin reuptake inhibitors (SSRIs) frequently detected in aquatic environments, were tested by exposing constructed aquatic food chains to SSRIs under controlled laboratory conditions. Both of these ionizable, weak base pharmaceuticals showed lower bioaccumulation factors (BAFs) with increasing trophic level (i.e., no biomagnifications) in 2 3-level food chains (Acer platanoides, fed to Asellus aquaticus, in turn fed to Notonecta glauca or Pungitius pungitius). Mean sertraline BAFs in A. platanoides, A. aquaticus, N. glauca, and P. pungitus were 2200 L/kg, 360 L/kg, 26 L/kg, and 49 L/kg, respectively, and mean fluoxetine BAFs 1300 L/kg, 110 L/kg, 11 L/kg, and 41 L/kg, respectively. The weak influence of diet was further demonstrated by measured BAFs being equal to or lower than measured bioconcentration factors (BCFs). Organism lipid content was not positively correlated with BAFs, suggesting that other processes are driving interspecific differences in SSRI bioaccumulation. The empirically derived parameter values were introduced into a proposed bioaccumulation model, and a poor correlation was found between modeled and empirical BAFs (predicted r² = –0.63). In conclusion, the apparent lack of biomagnification of these ionizable pharmaceuticals suggests that environmental concern should not necessarily focus only on higher trophic levels, but also on species showing high BCFs at any trophic level. Environ Toxicol Chem 2017;36:1029–1037.