September 2013
The MixTox project was presented at the Norwegian Research Council project fact sheets. See this page for details.

March 2013
MixTox partners Karina Petersen and Knut Erik Tollefsen participated and Co-chaired a workshop on combined toxicity entitled “Cocktail effects of environmental pollutants to human and wildlife health in the northern Norway and Arctic regions” at the Fram Centre , Tromsø,  Norway (21-22. March). The workshop hosted internationally leading scientists as keynote presenters combined toxicity state of the art and led to inter-disciplinary discussions on how to progress work on combined toxicity in the Arctic. details can be found in the workshop program (.pdf).

January 2013
A special session on Combined toxicity was organized by the Norwegian Society for Pharmacology and Toxicology (NSFT) annual scientific conference the 24th of January 2013. Project partners from MixTox were co-organisers and presented data from the MixTox project during the session.  Abstracts from the presentations can be found in the NSFT conference program (.pdf).

December 2012
Petersen completes PhD

Karina Petersen defended her thesis on December 12th 2012. The thesis was titled “Combined toxicity assessment of organic pollutants in small-scale fish bioassays” and was completed at the University of Oslo.

A summary of the thesis:
The desire for fewer experiments involving animals has led to the development of alternative testing methods to examine the effects of environmental pollutants.

Rainbow trout liver cells and transgenic zebra fish embryos have been used to characterize the acute toxic, estrogenic and anti-estrogenic effects of environmental pollutants, both individually and in mixtures.

Environmental pollutants occur as complex mixtures in the environment and pollutants with the same behavior may have additive effects. Additive effects of mixtures can be calculated using mathematical models.

In this study, the two models concentration addition and response addition were used to predict the effect of different mixtures of liver cells from rainbow trout or in transgenic zebra fish embryos.

Effects of the mixture of environmental pollutants could largely be predicted using the models of concentration addition and response addition based on data for each substance in the compositions.

Effects of mixtures of naphthenic acids on liver cells matched up with the calculated values ​​based on concentration addition. Mixtures of estrogenic substances consisting of estrogens and less potent organic pollutants such as bisphenol A and alkylphenol, matched up well with the calculated values ​​of concentration addition and response addition, but the models did not match up at the highest concentrations, where the observed estrogenic effect was lower than calculated.

Measured effects of mixtures of anti-estrogenic substances assumed to have equal modes of action, such as a mixture of polyaromatic hydrocarbons (PAHs), also matched up well with the calculated values ​​provided by the two models.

A mixture of anti-estrogenic compounds with other compounds with different modes of action had a stronger anti-estrogenic effect than predicted, suggesting that cellular interactions between different processes contributed to increasing the anti-estrogenic effect.

The trial lecture was titled: The chemical defensome of the cell - a comparative perspective.

Supervisors have been Knut Erik Tollefsen, Ketil Hylland and Kevin Thomas.

Karina (on the right) with her opponents: prof. Helmut Segner, Centre for Fish and Wildlife Health, University of Bern, Sveits, førsteam. Line E.T. Sverdrup, Dept. of Biology, University of Oslo og prof. Anders Goksøyr, Dept. of Biology, Universitetet i Bergen. Foto: Knut-Erik Tollefsen.


October 2012
Taylor & Francis Book Award for best student presentation awarded to You Song for the talk “Use of gene expression responses to evaluation combined effect of low dose gamma radiation and uranium on Atlantic salmon (Salmo salar)” at the 4th Norwegian Environmental toxicology symposium, Tromsø, Norway. You Song  is a PhD at Institute for Plant and Environmental Sciences, University of Life Sciences (UMB) and has conducted his PhD work on multiple stressors in collaboration with the MixTox project.

May 2012
Best Publication award presented to Karina Petersen

Karina Petersen (NIVA) received the award for the paper “Assessing combined toxicity of estrogen receptor agonists in a primary culture of rainbow trout hepatocytes” during the SETAC World conference in Berlin, 23rd of May, 2012.

The award is one of three best publication awards handed out by SETAC to students or early career scientists. Karina received the award sponsored by AstraZeneca for the best publication in Risk assessment, modelling and theoretical studies.

The paper is part of the NFR-project 178621 “Assessment of mixture toxicity of organic compounds in discharges to the North Sea and coastal areas of Norway (MixTox)” managed by Knut Erik Tollefsen. The work focuses on the use of cell based (in vitro) methods to predict combined effects of mixtures of endocrine disruptive chemicals as an alternative to time and resource consuming studies with live fish.

Karina’s work supports NIVA’s efforts to reduce the use of animals in ecotoxicological research (see based on the principle of the 3 Rs (replacement, reduction and refinement).

In the award winning study, Karina looked at the combined effects of four mixtures of up to seven chemicals with known estrogenic effect and found that they act additive on the production of a biomarker for estrogenic chemicals. All four tested mixtures had an additive effect at the low to intermediate total mixture concentrations. At the highest concentrations the effects of the mixtures were lower than the predictions based on the effects of the individual compounds. 

Several published in vivo studies have also reported additive effects of mixtures of estrogenic chemicals and verifies the value of the cell based model as a good screening method for estrogenic chemicals and mixtures of these.


July 2011
Participation on the ECETOC workshop – Effects of Chemical Co-exposures at doses relevant for Human Safety Assessments.
Karina Petersen participated in the ECETOC workshop “Effects of Chemical Co-exposures at doses relevant for Human Safety Assessments”, in Berlin, Germany (11-12th of july). The outcome of the workshop is presented in the ECETOC technical report No. 115.

June 2011
Knut Erik Tollefsen Awarded the NORECOPA prize  for development of non-animal (alternative) animals models and advancement of the 3Rs (Reduction, Replacement and Refinement) in ecotoxicological research

Sist oppdatert 17.09.2015