Antimicrobial activity of pharmaceutical cocktails in sewage treatment plant effluent – An experimental and predictive approach to mixture risk assessment

• Municipal wastewater contains multi-component mixtures of active pharmaceutical ingredients (APIs). This could shape microbial communities in sewage treatment plants (STPs) and the effluent-receiving ecosystems. In this paper we assess the risk of antimicrobial effects in STPs and the aquatic environment for a mixture of 18 APIs that was previously detected in the effluent of a European municipal STP. Effects on microbial consortia (collected from a separate STP) were determined using respirometry, enumeration of culturable microorganisms and community-level physiological profiling. The mixture toxicity against selected bacteria was assessed using assays with Pseudomonas putida and Vibrio fischeri. Additional data on the toxicity to environmental bacteria were compiled from literature in order to assess the individual and expected joint bacterial toxicity of the pharmaceuticals in the mixture. The reported effluent concentration of the mixture was 15.4 nmol/l and the lowest experimentally obtained effect concentrations (EC10) were 242 nmol/l for microbial consortia in STPs, 225 nmol/l for P. putida and 73 nmol/l for V. fischeri. The lowest published effect concentrations (EC50) of the individual antibiotics in the mixture range between 15 and 150 nmol/l, whereas 0.9–190 μmol/l was the range of bacterial EC50 values found for the non-antibiotic mixture components. Pharmaceutical cocktails could shape microbial communities at concentrations relevant to STPs and the effluent receiving aquatic environment. The risk of antimicrobial mixture effects was completely dominated by the presence of antibiotics, whereas other pharmaceutical classes contributed only negligibly to the mixture toxicity. The joint bacterial toxicity can be accurately predicted from the individual toxicity of the mixture components, provided that standardized data on representative bacterial strains becomes available for all relevant compounds. These findings argue for a more sophisticated bacterial toxicity assessment of environmentally relevant pharmaceuticals, especially for those with a mode of action that is known to specifically affect prokaryotic microorganisms. Pharmaceutical cocktails pose a risk to microbial communities in sewage treatment plants and the aquatic environment. © 2017 Elsevier Ltd

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

Nyckelord

Antibiotics

Environmental bacteria

Microbial communities

Mixture toxicity

Aquatic organisms

Effluent treatment

Effluents

Microorganisms

Mixtures

Risk assessment

River pollution

Sewage treatment plants

Toxicity

Active pharmaceutical ingredients

Anti-microbial activity

Community level physiological profiling

Culturable microorganisms

Prokaryotic microorganism

Sewage-treatment plant effluent

Bacteria

acebutolol

carbamazepine

ciprofloxacin

clofibric acid

diclofenac

enoxacin

fenofibrate

gemfibrozil

ibuprofen

lomefloxacin

metoprolol

naproxen

norfloxacin

ofloxacin

oxprenolol

propranolol

sulfamethoxazole

trimethoprim

antimicrobial activity

effluent

experimental study

microbial community

sewage treatment

wastewater treatment plant

Aliivibrio fischeri

aquatic environment

Article

bacterial strain

chemical analysis

concentration (parameters)

controlled study

microbial consortium

nonhuman

physiological process

Pseudomonas putida

quantitative analysis

sewage treatment plant

toxicity testing

Europe

Apis

Bacteria (microorganisms)

Prokaryota

Vibrio fischeri

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