A drug that is commonly used to treat anxiety in humans and which regularly finds its way into surface waters through wastewater effluence has been shown to reduce mortality rates in fish.
The results, which have been published today, 8 August, in IOP Publishing's journal Environmental Research Letters, may have significant implications for existing standard ecotoxicological tests, which predominantly focus on harmful effects of water contaminants and ignore the potential benefits.
By improving the health of an aquatic organism, a certain pharmaceutical drug may alter the balance of species in an environment and have serious, cascading ecological consequences, according to the researchers from Ume University in Sweden.
Lead author of the paper Dr Jonatan Klaminder, said: "Ecotoxicological tests were designed with traditional toxic contaminants in mind, such as heavy metals and dioxins, which have historically been the major apparent threat against aquatic organisms in surface waters.
"Pharmaceuticals, which are designed to improve health, are a new group of contaminants that do not necessarily fit into the traditional view.
"I think there is a 'bandwagon effect' within the research community where the old test and the traditional view of a contaminant is routinely used without reflection about the conceptual flaw implicit in the methods."
In their study, the researchers retrieved two-year-old Eurasian perch from a lake in Sweden and randomly exposed them to high and low concentrations of Oxazepam.
Oxazepam is a benzodiazepine which is commonly used to treat anxiety and insomnia in humans and regularly contaminates surface waters via treated wastewater effluent. The researchers have previously shown that the drug can increase the activity and boldness of Eurasian perch.
In this study, the low concentration of Oxazepam was below that measured in treated effluent water in Europe.
|Contact: Michael Bishop|
Institute of Physics