MixTox

Assessment of combinex toxicity of pollutants to the North Sea and Norwegian coastal areas through use of experimental and predictive modelling. NIVA addresses this challenge in the multi-national and multi-disciplinary research project MixTox funded by the Norwegian Research Council.

Background

The North Sea and coastal areas of Norway receive input of pollutants from various sources including discharges from land, maritime and offshore oil production activities, leakage from contaminated sediments and long-range atmospheric transport (fig. 1). These compounds exist as complex mixtures in the recipient and may consequently evoke effects through combination toxicity (mixture toxicity).

Due to lack of knowledge on the combined effects of marine pollutants and their mechanisms of effect, prediction of environmental impact and assessment of environmental risk are often assessed based on individual components and lack the ability to integrate combined toxicity, multiple mechanisms of effect and long-term effects due to more subtle mechanisms of toxic action. The lack of ability to address combined toxicity of chemicals in complex mixtures thus introduces a need for developing effect methods capable of addressing acute and chronic effects as well as implementation of prediction models that can be used to characterize the interaction occurring.

Project

The Norwegian Institute for Water Research (NIVA)  managed a Norwegian Research Council (NRC) funded project “178621-Assessment of mixture toxicity of compounds in discharges to the North Sea and coastal areas of Norway (MixTox)” in the period 2007-2012.

Objectives

Determine the combined effects (mixture toxicity) of typical complex organic chemical mixtures originating from multiple exposure sources in Norwegian coastal areas and the North Sea. To evaluate whether the modelling approach is applicable to Norwegian exposure scenarios, assessment of the mixture toxicity of selected coastal discharges and contaminated harbour sediments will be performed.

Work packages

The proposed work will be divided into four work packages (WPs) where data and experiences will be shared between WPs (Fig 2.).

WP 1: Construct a PBT exposure database that allow identification of compounds in emissions from North sea and coastal emissions of high concern
 
WP 2: Assessing combined toxicity of compounds identified in WP1 in a battery of small-scale/in vitro bioassays using state-of-the-art prediction models
 
WP3: verify combined toxicity in fish embryos as a model system for small fish species
 
WP4: using a combination of effect-directed analysis (EDA) and combined toxicity prediction modelling to address mixture toxicity under relevant exposure scenarios.