Estuary (left: photo credit Dr. Rob Ellis) and Worm (right: photo credit Cameron Hird)

Are our pharmaceuticals a burden on aquatic life?

What happens when pharmaceuticals reach the marine environment? Marine biologists from Exeter have published the results of their recent investigations in Environmental Science & Technology last month. In their article, they highlight the impact that human pharmaceuticals can have on aquatic species.

Nowadays, most of the general public are aware that pharmaceuticals should be used wisely, because of the harmful consequences that misuse or abuse can trigger in  patients, from common side-effects (subjected by the majority of medications) to antimicrobial resistance, in the case of antibiotics. But everyday medications can also potentially affect negatively our environment and its biome, as demonstrated recently by Biosciences PhD student Cameron Hird and his team, led by Professor Tamara Galloway.

Together, they chose to focus their work on fluoxetine, a common anti-depressant drug acting on serotonin concentrations in the nervous system, the neurotransmitter that is often linked to feeling of happiness and well-being. Indeed, fluoxetine concentrations in sewage effluents in the UK and USA have been previously shown to exceed, those recommended by the Water Framework Directive. Such high concentrations are usually found close to sewage-treatment plants. In a recent issue of Environmental Science & Technology, these researchers from Exeter demonstrated the biological effect this drug can have on marine ragworms (Hediste diversicolor).

Using novel methods like Mode-of-Action (MoA) and trait-based approaches, they have measured the uptake of fluoxetine by marine worms and investigated the biological effects this pharmaceutical compound can have. When exposed to fluoxetine, they could see some of its effects in the worms, with serotonin concentrations in fluid extracted from the worms’ main body cavity having increased by around 10%. Commenting on this, Cameron Hird adds that “antidepressants affect marine worms via the same biological pathways as they do in humans with potentially negative ‘side effects’ as a consequence”. Indeed, these worms experienced reduced feeding, weight loss and changes in metabolism, for example with the alteration of their oxygen consumption and ammonia excretion rates.

Altogether, these results show that marine species can suffer from environmental exposure to our pharmaceuticals. Cameron Hird stated “As a society we take pharmaceuticals for granted without appreciating that there is an environmental cost associated with their use. Many are not completely removed during sewage treatment and pollute our estuaries and coastlines”. Given this environmental risk, it is therefore necessary to optimize our sewage-treatment methods, correctly dispose of unused medications, and reconsider unnecessary uses of such pharmaceutical compounds.

Read the full article.

Written by Cyrielle Tonneau, Biosciences Pressgang.

Date: 20 September 2016

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