SURROGATE PARAMETER FOR THE BASE-LINE TOXICITY CONTENT OF CONTAMINATED WATER - SIMULATING THE BIOCONCENTRATION OF MIXTURES OF POLLUTANTS AND COUNTING MOLECULES

A large part of all environmental pollutants can be classified as narcosis-type chemicals with regard to acute aquatic toxicity. This baseline, or narcosis-type, toxicity is generally assumed to be brought about through one and the same mechanism. The effects of these chemicals are directly related to their (equilibrium) body burden. This implies that the 'total baseline toxicity content' of an aquatic sample is dependent only on the cumulative body burden of these compounds and that this could be made into an important parameter in risk assessment for the aquatic ecosystem. A simple procedure to simulate the biotic body burden of a mixture of pollutants, by using C-18-Empore disks and to subsequently quantify this cumulative body burden on the basis of molar concentrations by means of vapor pressure osmometry is described. This procedure fulfils the requirements of a true surrogate parameter for the estimation of the total baseline toxicity content of environmental water samples by obviating the need of identifying and quantifying individual compounds and by enabling an estimation of the contribution of baseline toxicity to the overall toxicity of surface waters and effluents.