Fluoxetine Exhibits Pharmacological Effects and Trait-Based Sensitivity in a Marine Worm

Abstract

Global production of pharmacologically active compounds exceeds 100 000 tons annually, a proportion of which enters aquatic environments through patient use, improper medicine disposal, and production. These compounds are designed to have mode-of-action (MoA) effects on specific biological pathways, with potential to impact nontarget species. Here, we used MoA and trait-based approaches to quantify uptake and biological effects of fluoxetine, a selective serotonin reuptake inhibitor, in filter and deposit feeding marine worms (Hediste diversicolor). Worms exposed to 10 μg L(-1), accumulated fluoxetine with a body burden over 270 times greater than exposure concentrations, resulting in ∼10% increased coelomic fluid serotonin, a pharmacological effect. Observed effects included weight loss (up to 2% at 500 μg L(-1)), decreased feeding rate (68% at 500 μg L(-1)), and altered metabolism (oxygen consumption, ammonia excretion, and O/N from 10 μg L(-1)). Bioconcentration of fluoxetine was dependent on route of uptake, with filter feeding worms experiencing up to 130 times greater body burden ratios and increased magnitudes of effects than deposit feeders, a trait-based sensitivity likely as a consequence of fluoxetine partitioning to sediment. This study highlights how novel approaches such as MoA and trait-based methods can supplement environmental risk assessments of pharmaceuticals.

A review of the pharmaceutical exposome in aquatic fauna

“…The difference between laboratory and field estimations of accumulation could be attributed to dietary assimilation and other environmental/ecological factors such as feeding strategy, habitat choice, water chemistry and bioavailability ( Vignati et al., 2007 ; Hird et al., 2016 ). As in vivo tests do not often include dietary exposure, it has been suggested that this may underestimate the accumulative potential of a compound ( Lagesson et al., 2016 ).…”

‘Prescribing’ psychotropic medication to our rivers and estuaries

“…What is particularly starting to interest scientists is that these antidepressants can cause disruption to the normal functioning of aquatic life in laboratory experiments at low concentrations. The uptake of these compounds appears to be highly dependent on the organism's mode of feeding 9 . In terms of presence in the environment, for example, diazepam has been found in all matrices – wastewater, surface, ground and drinking water, soils, bio-solids and tissues 10 – and in concentrations as high as 10 ng/L in rivers and potable water 11…”