Since the almost classic publication by Daughton and Ternes in 1999 [1], the issue of pharmaceuticals in the environment has gained tremendous attention. This might also be due to the fact that ethinylestradiol, the hormonally active agent of the contraceptive pill, has be shown to affect the normal development of wildlife, for example fish [2,3]. What is a pharmaceutical in the pill turns into an endocrine disrupter as soon as it leaves the female body…

The poisoning of vultures on the Indian subcontinent might provide the most drastic example of the effects of pharmaceutials in the environment: vulture populations have crashed by more than 95% due to Diclofenac poisoning, an ordinary pain killer. The birds are exposed by feeding on carcasses, originating from cattle previously treated with Diclofenac [4].

Although several pharmaceuticals, such as for example the non-steriodal painkillers to which Diclofenac belongs, are used in amounts that resemble the tonnages of ordinary pesticides, we still do not know very much of their ecotoxicologial effects. Data on their chronic toxicity are found only sparsely in the open scientific literature – although the situation has improved over the last years.

My main research interests concerns the ecotoxicological effects that pharmaceuticals might have on environmental microorganisms, especially bacteria and algae. Besides working with isolated single species of bacteria and algae, we also analyse the ecotoxicology of pharmaceuticals in a more ecological setting. For this purpose we expose natural biofilms (so-called periphyton) to the compounds. To the right you can see a microscopic photo of  such a biofilm –  the different shapes of the different species that make up the biofilm periphyton1

are clearly visible. How do those highly complex communities that fullfill vital ecological functions such as nutrient recycling or primary production react to the slight but chronic exposure to pharmaceuticals and their mixtures?

We recently published an investigation on the ecotoxicology of Clotrimazole, a common antifungal agent that is used for treating dermal fungal infections in humans. We could demonstrate that concentrations that were detected in UK estuaries actually have drastic impacts on exposed biofilms [5]. Especially the pattern of sterols, which are essential building blocks of the cellular membrane, are severely affected by an exposure to that compound. Below you can see a reprinted figure from that study, showing effects already at ng/L levels.

clotrimazol effects

[1] C G Daughton and T A Ternes (1999) Pharmaceuticals and personal care products in the environment: agents of subtle change? Environ Health Perspect. 1999 December; 107(Suppl 6): 907–938. link to full article

[2] Purdom C, Hardiman P, Bye V, Eno N, Tyler C, Sumpter J (1994) Estrogenic effects of effluent from sewage works. Chemical Ecology 8:275-285

[3] Nash JP, Kime DE, Van der Ven LT, Wester PW, Brion F, Maack G, Stahlschmidt-Allner P, Tyler CR (2004) Long-term exposure to environmental concentrations of the pharmaceutical ethynylestradiol causes reproductive failure in fish. Environ Health Perspect 112:1725-1733, link to full article

[4] Oaks JL, Gilbert M, Virani MZ, Watson RT, Meteyer CU, Rideout BA, Shivaprasad HL, Ahmed S, Chaudhry MJ, Arshad M, Mahmood S, Ali A, Khan AA (2004) Diclofenac residues as the cause of vulture population decline in Pakistan. Nature 427:630-633

[5] Porsbring, T. Blanck, H. Tjellström, H. Backhaus, T. “The toxicity of the human pharmaceutical Clotrimazole to natural marine microalgal communities” Aquatic Toxicology, 91, 203-211, 2009, doi:10.1016/j.aquatox.2008.11.003

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