Toxicity bioassays with concentrated cell culture media\u2014a methodology to overcome the chemical loss by conventional preparation of water samples

Frida Niss,Johan Lundqvist,Geeta Mandava,Anna Kjerstine Rosenmai,Agneta Oskarsson,Stefan Örn

doi:10.1007/s11356-018-1656-4

Abstract

The use of in vitro bioassays for studies of toxic activity in environmental water samples is a rapidly expanding field of research. Cell-based bioassays can assess the total toxicity exerted by a water sample, regardless whether the toxicity is caused by a known or unknown agent or by a complex mixture of different agents. When using bioassays for environmental water samples, it is often necessary to concentrate the water samples before applying the sample. Commonly, water samples are concentrated 10–50 times. However, there is always a risk of losing compounds in the sample in such sample preparation. We have developed an alternative experimental design by preparing a concentrated cell culture medium which was then diluted in the environmental water sample to compose the final cell culture media for the in vitro assays. Water samples from five Swedish waste water treatment plants were analyzed for oxidative stress response, estrogen receptor (ER), and aryl hydrocarbon receptor (AhR) activity using this experimental design. We were able to detect responses equivalent to 8.8–11.3 ng/L TCCD for AhR activity and 0.4–0.9 ng/L 17β-estradiol for ER activity. We were unable to detect oxidative stress response in any of the studied water samples. In conclusion, we have developed an experimental design allowing us to examine environmental water samples in toxicity in vitro assays at a concentration factor close to 1, without the risk of losing known or unknown compounds during an extraction procedure.

Highlights

The application of bioanalytical tools, such as in vitro bioassays, for toxicity studies in environmental water samples is a rapidly expanding field of research (Escher et al 2012; Tang et al 2014; Busch et al 2016; Lillicrap et al 2016; Mehinto et al 2016; König et al 2017; Kunz et al 2017; Neale et al.2017a, b; Tan and Schirmer 2017)
We have developed an alternative experimental design by preparing a concentrated cell culture medium which was diluted in the environmental water sample to compose the final cell culture media for the in vitro assays
The oxidative stress response was assayed in HepG2 cells transiently transfected with an Nrf2 sensitive luciferase plasmid

Summary

Introduction

The application of bioanalytical tools, such as in vitro bioassays, for toxicity studies in environmental water samples is a rapidly expanding field of research (Escher et al 2012; Tang et al 2014; Busch et al 2016; Lillicrap et al 2016; Mehinto et al 2016; König et al 2017; Kunz et al 2017; Neale et al.2017a, b; Tan and Schirmer 2017). A large part of the environmental monitoring efforts are based on chemical analysis of known environmental pollutants. Chemical analysis is not necessarily linked to adverse outcome and ignore possible mixture effects. Based on these limitations, and the rapid development of in vitro bioassays, it has repeatedly been suggested that a combination of chemical characterization and toxicological profiling would be a more suitable way of performing environmental monitoring, for a better understanding of the effects of environmental pollutants (Escher and Leusch 2012; Escher et al 2013, 2017; Malaj et al.2014; Petrie et al 2015; Ankley et al 2016; Brack et al.2016, 2017)

Methods

Results

Conclusion