The conceptual imperfection of aquatic risk assessment tests: highlighting the need for tests designed to detect therapeutic effects of pharmaceutical contaminants

Abstract

Standardized ecotoxicological tests still constitute the fundamental tools when doing riskassessment of aquatic contaminants. These protocols are managed towards minimal mortality in the controls, which is not representative for natural systems where mortality is often high. This methodological bias, generated from assays where mortality in the control group is systematically disregarded, makes it difficult to measure therapeutic effects of pharmaceutical contaminants leading to lower mortality. This is of concern considering that such effects on exposed organisms still may have substantial ecological consequences. In this paper, we illustrate this conceptual problem by presenting empirical data for how the therapeutic effect of Oxazepam-a common contaminant of surface waters-lower mortality rates among exposed Eurasian perch (Perca fluviatilis) from wild populations, at two different life stages. We found that fry hatched from roe that had been exposed to dilute concentrations (1.1 ± 0.3 μg l −1 ) of Oxazepam for 24 h 3-6 days prior to hatching showed lower mortality rates and increased activity 30 days after hatching. Similar effects, i.e. increased activity and lower mortality rates were also observed for 2-year old perch exposed to dilute Oxazepam concentrations (1.2 ± 0.4 μg l −1 ). We conclude that therapeutic effects from pharmaceutical contaminants need to be considered in risk assessment assays to avoid that important ecological effects from aquatic contaminants are systematically missed.

Ecological effects of pharmaceuticals in aquatic systems—impacts through behavioural alterations

“…One important step towards more realistic risk assessments of ecological effects of pharmaceuticals would be to incorporate standardized assays of ecologically important behaviours of consistent nature (e.g. activity, boldness and sociality) [95].…”

Drug-Induced Behavioral Changes: Using Laboratory Observations to Predict Field Observations

“…Changes in water chemistry modulate the GABA system by lowering the action potential in the GABA-A receptor and this results in GABAergic behavioral modification (GBM). These behavioral modifications, as ecological theory predicts, increase predation risk and mortality (Munday et al, 2010;Brodin et al, 2013;Klaminder et al, 2014). Therefore, GBMs as the result of changes in water chemistry could severely decrease marine fish populations in the near future (Munday et al, 2010;Ou et al, 2015).…”

“…To generate GBMs, a group of perch (N = 17; mean length = 112 mm; SD = 10) were prior to the behavior assay exposed to water containing nominal concentrations of 200 ug L −1 of dissolved oxazepam for 5 days. This concentration of oxazepam was used because it is within the range of concentrations previously seen to generate GBMs in perch (Brodin et al, 2013;Klaminder et al, 2014). That is, the exposure was chosen to guarantee an effect that did not induce any direct negative (toxic) effects.…”

Dose-dependent fluoxetine effects on boldness in male Siamese fighting fish

“…However, because many of the PPCPs found in aquatic environments have been specifically designed to alter behavior, behavioral endpoints are potentially more relevant indicators of species risk than physiological changes (Jones et al, 1991;Brooks et al, 2003;Lovern et al, 2007). Additionally, the use of standardized behavioral assays that incorporate behaviors of direct and indirect importance to ecosystem functioning could greatly improve our understanding of the effect of pharmaceutical exposure on wildlife Klaminder et al, 2014).…”