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(20-03) Influence of data variability on fate and risk of PAHs in a terrestrial environment. Fauser, Patrik*,1, Thomsen, Marianne1, 1 National Environmental Research Institute, Roskilde, Denmark ABSTRACT- The fate and risk assessment of hydrophobic substances in the terrestrial environment can be associated with large errors. These can arise from the partitioning and process coefficients derived in experimental studies, and from the model set-up designed to calculate the exposure concentrations. It is possible to utilise the knowledge concerning the experimental and theoretical uncertainty to obtain a stochastic estimate of the risk. This work investigates the influence of the variability of fate and effect parameters on the risk of selected Poly Aromatic Hydrocarbons, PAHs, in a terrestrial environment. Experimental investigations on the effects of the PAHs on three different terrestrial organisms give information on PNEC and the associated probability distributions. Effect parameters are closely linked to the bioavailable, i.e. dissolved, concentration in the soil. In order to calculate this fraction the sorption of PAHs to the soil must be quantified. From the literature, values on sorption coefficients for the selected PAHs are gathered, and QSARs are developed where data is missing. The data and QSAR estimates with probability distributions are used in a compartment model for a terrestrial system, and the exposure concentrations, i.e. PECs, of the PAHs are calculated. Each PAH is now represented by PEC and PNEC values with associated uncertainties. The risk, PEC/PNEC ratio, is not a point estimate but comprise a probability range derived from two probability distributions. This approach can be more informative and scientifically correct than the conventional deterministic risk assessment of chemical substances in the environment. Key words: Fate, PAH, PEC, risk |
